Tài liệu Urban Transportation Systems: Choices for Communicaties pptx

The large ancient and medieval cities were actually conglomer-ations of neighborhoods in which daily life could take place 1Mobility is here defined as the ability of any person to move

C H A P T E R

Overview—Criteria for Selecting Modes

Life in cities—i.e., in organized human settlements, which are

mostly referred to as communities in this book—is possible only if

people have mobility1

on a daily basis—the ability to move around

so that they can do what they have to do or like to do One

char-acterization of a city is that it consists of specialized, frequently

clustered, activities that perform discrete functions Residences

are separate from workplaces, major shopping is concentrated in

identifiable centers, and larger entertainment and relaxation

facil-ities are found at specific locations They have to have

accessi-bility.2 Unlike in a village, very few of these destinations are

reachable on foot; at least, they tend not to be within a convenient

walking distance

The large ancient and medieval cities were actually

conglomer-ations of neighborhoods in which daily life could take place

1Mobility is here defined as the ability of any person to move between points in

a community by private or public means of transportation The usual obstacles

to mobility are long distances, bad weather, steep hills (all constituting friction

of space), but, above all, the unavailability of services, high fares, and possibly

other forms of exclusion.

2Accessibility is here defined as the possibility of reaching any activity,

estab-lishment, or land use in a community by people (or by conveyances of goods or

information) who have a reason to get there It is a measure of the quality and

operational effectiveness of a community.

within a short radius; only occasionally was a longer trip to amajor event necessary Industrialization during the nineteenthcentury caused a true urban revolution by disaggregating thesmall-scale pattern into metropolitan structures with strong andintensive production and service zones Assisted transportationbecame mandatory, and was, indeed, quickly invented—horsecars, steam railroads, electric streetcars, and eventually under-ground metro (electric heavy rail) systems.

The twentieth century brought further development of the railmodes, and introduced individual motor (gasoline- and diesel-powered) vehicles—buses and automobiles The latter came todominate the transportation field, at least in North America, anddispersed the urban pattern further into sprawl We are all famil-iar with this situation, since this is our environment, and it hasbeen examined endlessly by scholars, journalists, and concernedcitizens What is not quite so apparent is that urban life and spa-tial patterns are entering a new, postindustrial, period, which ischaracterized by the emergence of many dispersed special-purpose centers (not just the historic single all-purpose center),overall low densities, and movement in many different directions

at any given time with diverse trip purposes Electronic nications systems play an increasingly large role All this makes itmore difficult to operate effectively the traditional transportationmodes that served us well under more structured conditions.Everything has not changed, but the task of providing responsivetransportation services is now more challenging Also, the expec-tations are higher

commu-There is a large inventory of available means of mobility today,most of them tested under various conditions in various places Inthe United States, it is not just a question of how to cope with theautomobile—admittedly a very seductive mode—but rather ofhow to equip our communities with a reasonable array of trans-portation choices, so that the best aggregate level of mobility isoffered to all people Never before has any other culture enjoyedthe same freedom of movement, but there are deficiencies: noteverybody can take full advantage of the current car-based trans-portation capabilities, and the systems that we do have are notnecessarily (quite unlikely, in fact) the best, the most economical,the cleanest, and the most responsive options that could be pro-vided The vehicular pollution problem is perhaps on the verge ofbeing solved, if some serious additional effort is applied, butplenty of other issues remain

The trends and problems are global, and while the scope of

inquiry of this book is definitely directed to North America, these

concerns do not exist in isolation, certainly not as far as

trans-portation technology is concerned It is common practice to refer to

“industrialized countries” as having special needs and

capabili-ties—which is an obsolete concept, because industry (i.e.,

manu-facturing) is no longer the determining factor The search for a

proper label has some significance “Advanced countries” is a

pompous and patronizing characterization that does not contribute

much to an operational discussion “Peer countries” has some

validity, but only if everything is compared to a U.S situation

“Developing countries,” on the other hand, is a very common term

that helps to summarize broad descriptions, but obscures the fact

that there is tremendous variety among these countries Saudi

Ara-bia, Brazil, Kenya, and Indonesia do not fit in the same box easily

The fact of the matter is that cities and their populations are

not homogeneous in different parts of the world, not even within

the same country (not even in Sweden) Each city has components

that range in their transportation expectations from the most

comfortable to the most affordable There are districts in African

cities that expect and can pay for the most advanced services, and

there are neighborhoods in American metropolitan areas that are

not much different from those found in Third World countries

The relative size of the various user cohorts is, of course,

differ-ent, but the demands within them are quite similar

Therefore, for the purposes of examining transportation needs,

it can be suggested that we recognize the presence of various

eco-nomic and social classes (user groups) that react differently to

transportation systems and have to be serviced differently In a

perfect world, such distinctions would not have to be made, since

everybody is entitled to mobility Equity is an important concept,

and social reforms are undoubtedly needed in many instances,

but the duty of urban transportation is to provide service for

com-munities the way we find them today Purposeful and relevant

change comes next, but upgraded mobility systems can only do so

much in implementing community reforms

Thus, to define a base for the discussion of transportation

modes, the following distinctions that are present in any society

can be made:

• The affluent elite. This group is basically separate and only

barely visible from the outside The members live and play

in their own enclaves and have their own means of mobility(limousines and private jets) They do not affect the rest of

us, except to cause some envy; they do not participate indaily urban operations, and they do not use the subway.They do have much influence in decision making

expecta-tions from transportation services as everybody else—rapid,comfortable, and secure accommodations—but members ofthis group can exercise a choice and be selective They insist

on control over their private space, and they might use lic transportation, but only if it meets very high standards.The expense of transportation is not a significant barrier;the demand is for individually responsive means of uncon-strained mobility The private automobile does this (most ofthe time), and there is an open question as to what propor-tion of Americans falls in this group of dedicated motoristswho have no other choices in mind

pub-• The middle class. This group has largely the same attitudes

as the previous group, except that they operate with morefrugal means They include among their members propor-tionally more individuals who will favor public transporta-tion as a matter of principle and the proper thing to do Ithas always been the case that the professional and educatedclasses lead the public debate, start revolutions, anddemand reforms They have to be counted on as the formu-lators of public opinion, and they will determine policydirections in places where they constitute a vocal presence

It is a fact that members of this group, whether they areArgentines, Egyptians, Belgians, or Americans, will act andbehave in the same way and demand the same type of ser-vices and facilities They all read the same books and drivethe same cars The only differences among them are theirrelative proportion of the populace in any given society andsome cultural variations Europeans, for example, cherishtheir old city districts; Americans regard them as quaint

“theme” areas; and members of emerging societies are stillfrequently embarrassed by them

• The surviving cohort. This group consists of working ple of modest means whose principal preoccupation is basicexistence They have little influence on decisions and politi-

peo-cal processes—except in instances where they constitute the

overwhelming majority and are politically organized They

need and deserve transportation services, but they cannot

afford high charges, and their choices tend to be limited

Some degree of subsidy will almost always be necessary to

attain acceptable service levels

• The disadvantaged class. This group includes the poor and

those who have some personal handicap and insufficient

resources to purchase proper services Poverty always comes

at different levels, but the problems are universal and

unfor-giving This group represents the largest challenge to public

agencies and institutions in achieving basic mobility for all

No social assistance program really works unless physical

accessibility is ensured Communities in the United States

are certainly not immune from these requirements, and the

current “welfare-to-work” effort is only one example of the

initiatives needed

The preceding is not by any means intended to be a

sociologi-cal analysis of contemporary societies, but only a hypothesis of

how different populations react to mobility needs and services

provided More specifically, the adequacy of operations can be

looked at from three perspectives, which eventually leads to the

selection of a proper response or transportation mode:

• The point of view of the individual, which will stress

per-sonal attitudes and emphasize usually humanly selfish

con-siderations

• The policy of the community, which has to stress the

com-mon good and long-range capabilities

• The concerns related to national efficiency and well-being

The personal concerns will encompass the following:

• Time spent in travel. This includes time spent to reach the

vehicle or access point, to possibly wait, to actually travel,

to possibly transfer, and to reach the final destination

(prob-ably on foot)

• Costs incurred. These include primarily the out-of-pocket

expenses on any given trip (including possible tolls and

pur-chase of fuel), but there are also considerations of previous

investment (buying a car) and the sunk costs (investment in

equipment and insurance)

• Operational quality. This concerns reliability, safety (fromaccidents), and smoothness of motion.

activity), privacy, sanitation, climate control, seats, visualquality, and social standing

The communal concerns should include the following:

• Efficient networks and services. They should have the ity to support economic and social life, and cause minimaldisruptions and delays in normal urban operations

abil-• Efficient urban patterns. To the extent that transportationsystems can help to achieve more compact settlement forms,the configurations and activity locations should be deliber-ately shaped

• High degree of livability. Transportation modes should vide access to all places and establishments and have mini-mal local environmental and visual impacts

and local jobs should be boosted due to good transportation

• Fiscal affordability. Services should result in limited drain

on local resources, maximum use of external assistance,minimal indebtedness, and low annual contributions

change ordinances or regulations, modify labor rules, place families and establishments, disturb existing institu-tions, etc

dis-• Civic image and political approval. Services should includefeatures that are admired by outsiders and endorsed by localresidents (voters) and businesses

The national concerns exist at a higher and overarching level,and they might not always be achieved if left to local initiatives:

• Use of national wealth. This involves the implementationand operation of the most cost-effective systems, particu-larly as seen from the perspective of the national budget

• Conservation of fuel resources. This particularly concernsthose derived from petroleum

regions demands specific attention

• Equity. This is a concern to ensure that the needs of the

less-privileged members of society are specifically addressed

• National technological capability. Those systems that

en-hance technological advancement and production capacity

within the country should be emphasized

• Well-functioning, well-equipped, and balanced communities.

Such built environments should be created in all parts of the

country and within all metropolitan areas

Recognizing the fact that no proposed or existing

transporta-tion system can satisfy equally well three separate sets of criteria,

there is a need to amalgamate the preceding lists, perhaps even to

make some compromises There is also the practical consideration

that the discussion here has to move toward workable guidelines

for the selection of appropriate modes in any given urban setting.

This means that some of the considerations are so overarching

and basic that they simply have to be accepted as given; others

make no distinction among modes and, therefore, are not

opera-tive in the evaluation process Attention has to turn to functional

aspects All services and systems eventually exist and perform at

the local level in communities.

Trip Purpose and Clientele

Most transportation modes can make a reasonable claim to be

able to satisfy all trip purposes within a community They have

to, because no city can provide too many overlapping services

There are, however, modes that respond best to selected

situa-tions with identifiable needs These usually encompass

paratran-sit and various high-technology modes (shuttles and district

services) With respect to user groups, the options are more

com-plicated, because people tend to have differing expectations

These range from placing comfort features first to a single-minded

emphasis on affordability Concerns with equity very much enter

into these evaluations

Geographic Coverage and Grain of Access

The more capital-intensive modes best serve concentrated

corri-dors, and door-to-door accessibility has to be added by feeder

ser-vices The grain of the former has to be rather coarse, i.e., not able

to reach many dispersed points directly Any mode that attempts

to do the latter as communal transit for the sake of user nience will not be in a position to provide rapid service, because

conve-of the many stops that will have to be made To a large extent, thisconsideration explains the popularity of the private automobile

Carrying Capacity

Transportation modes available today cover a wide spectrum intheir ability to do work, i.e., carry people A fundamental andnot-too-difficult selection task is choosing a proper mode torespond to estimated demand volumes If the users from a districtnumber a dozen or so during a day, only individual street-basedvehicles (perhaps in joint use) can be considered; if they numberseveral tens of thousands, a subway will have to be built Thesuitable responses at the extreme ends of the scale will be expen-sive in one way or another

Speed

Time distances, not physical distances, are of concern here For

any given traveler in an urban situation, the maximum speed that

a vehicle or train can attain on an open channel is of little est; what matters is the total time consumed from the origin point

inter-to the destination and the inconveniences of transfers along theway The private automobile is a formidable competitor again,except on truly congested street networks The aggregate rapidity

of movement is also a communal concern to the extent that timespent in travel is unproductive and tiresome to the participants

Passenger Environment

In a prosperous society, personal comfort and convenience tures are increasingly significant If certain levels in quality of lifehave been attained in residences and workplaces, greatly inferiorconditions will not be tolerated during travel These featuresencompass the smoothness of the ride, privacy (or at least somedistance from strangers), sanitation, climate control, availability

fea-of seats, visual quality, and anything else that registers throughhuman senses The challenging task in communal transit is tomeasure up to what private cars provide

Reliability

Life in contemporary cities is stressful enough, and our society (aswell as our employer) expects punctuality Delays in traffic and

travel are acceptable only as rare occurrences There are modes

that are more immune to traffic overloads and bad weather

(rail-based, mostly), and there are others that are quite vulnerable to

urban disruptions (street-based, mostly)

Safety and Security

Residents in cities are well sensitized, through continuous media

attention, toward issues of personal safety and security—for good

reasons This is mostly a matter of the overall level of civilized

behavior in a community and police protection, but there are

modes that are perceived to be more susceptible to antisocial

action and physical breakdown than others

Conservation of the Natural Environment and Fuel

The attention paid lately to the quality of air and water around us

and the concerns with resource depletion enter in the planning

and design of many urban systems, particularly so with

trans-portation While these are national issues with national

man-dates, solutions can be achieved only through work at the local

level, even if the consequences of any individual small action may

be seen as marginal Generally speaking, transit is benign, and

low-occupancy automobile use is damaging

Achievement of a Superior Built Environment

We can continue to expect that major transportation systems that

significantly enhance the accessibility of specific nodes or

corri-dors will generate a positive effect on land use and distribution of

activities This feature has potential for organizing the urban

pat-tern, but evidence shows that this does not happen in all

instances and it does not happen automatically—unless other

constructive organizing programs are also implemented

Costs

The expenses associated with transportation improvements and

management can be broken down in considerable detail, but the

commonly listed elements are right-of-way acquisition,

construc-tion of the channel (roadway or guideway) and facilities, purchase

of rolling stock, and annual operation and maintenance expenses,

which include compensation for the work force, purchase of fuel

or power and supplies, maintenance of equipment and facilities,

and managerial expenditures Nothing is cheap, but some modes

involve massive capital investments, while others consume largeamounts of resources to run services and maintain hardware Itshould not matter in the long run whether the funds come frommunicipal, state, or federal budgets since they are all drawn fromthe wealth of the entire society and country, but it does matterwhen decisions have to be made with respect to any specific sys-tem The costs, either in their entirety or by separate components,are frequently, as might be expected, the life-or-death factors forany transportation project.

Implementability

This concern refers to elements that are complex, not always welldefined, and frequently obscure to the general public in the polit-ical and institutional realms, sometimes reflecting establishedpractices and habits They can be critical items if progress withany project is expected, and they may sometimes represent insur-

mountable barriers The engineers have an equivalent term— buildability—in public works construction But that is a com-

paratively easy task since it refers to the physical ability to getsomething done Implementability encompasses social, adminis-trative, and political arrangements and habits, often unique to aspecific community Transportation systems affect much morethan tangible artifacts and their operation These factors operate

at the local and state levels primarily, and no generalizations will

be made here, except to call for serious attention and standing well before any irreparable damage is done due toneglect or ignorance

under-Image

Transportation systems and services are the public face of a munity Everybody comes in contact with them, and they are usu-ally the first thing that a visitor from the outside experiences.They are elements of civic pride in many instances, and theyshow the seriousness that is applied to the creation of a livableand efficient community But pride can also be a sin, and thereare instances on record in which transportation solutions havebeen implemented for reasons other than functional necessity.This should not happen with full knowledge of the capabilitiesand potential of transportation modes in the contemporary city.There are legitimate reasons to applaud service systems that

com-respond to the needs and capabilities of a community, to take

pride in something that works well

We should be ready now to apply the preceding criteria as a

screen in reviewing the many transportation modes available for

service We shape our service systems, they do not shape us, but

they do have a fundamental role in defining the structure of

com-munities and how we live and operate in cities and metropolitan

areas Transportation systems and land use are two sides of the

same coin To achieve the exact built environment that we wish to

have, work with both of them in a mutually supporting fashion is

indicated The record from the past has not always been inspired;

we have the means, the methods, the choices, and, let us hope,

the knowledge today to do better

CAMBRIDGE, Mass.—

Many people who are

will-ing to concede that the

railroad must be brought

back to life are chiefly

thinking of bringing this

about on the very terms

that have robbed us of a

balanced transportation

network—that is, by

treat-ing speed as the only

important factor,

forget-ting reliability, comfort

and safety, and seeking

some mechanical dodge for

increasing the speed and

automation of surface

vehicles.

My desk is littered with

such technocratic fantasies,

hopefully offered as

“solu-tions.” They range from

old-fashioned monorails

and jet-propelled hovercraft

(now extinct) to a more

sci-entific mode of propulsion

at 2,000 miles an hour,

from completely automated

highway travel in private

cars to automated vehicles

a Government department

is now toying with for

“facilitating” urban traffic.

What is the function of

transportation? What

place does lomocotion [sic]

occupy in the whole

spec-trum of human needs?

Perhaps the first step in

The prime purpose of passenger transportation is not to increase the amount

of physical movement but

to increase the possibilities for human association, cooperation, personal intercourse, and choice.

A balanced tion system, accordingly, calls for a balance of resources and facilities and opportunities in every other part of the economy.

transporta-Neither speed nor mass demand offers a criterion

of social efficiency Hence such limited technocratic proposals as that for high- speed trains between already overcrowded and overextended urban cen- ters would only add to the present lack of functional balance and purposeful organization viewed in terms of human need.

Variety of choices, ties and destinations, not speed alone, is the mark of

facili-an orgfacili-anic trfacili-ansportation system And, incidentally, this is an important factor

of safety when any part of the system breaks down.

Even confirmed air ers appreciate the railroad

travel-in foul weather.

If we took human needs seriously in recasting the whole transportation sys- tem, we should begin with the human body and make the fullest use of pedes- trian movement, not only for health but for effi- ciency in moving large crowds over short dis- tances The current intro- duction of shopping malls, free from wheeled traffic,

is both a far simpler and

far better technical

solu-tion than the many costly proposals for introducing moving sidewalks or other rigidly automated modes

of locomotion At every stage we should provide for the right type of loco- motion, at the right speed, within the right radius, to meet human needs Nei- ther maximum speed nor maximum traffic nor maxi- mum distance has by itself any human significance.

With the exploitation of the motor car comes an increased demand for engineering equipment, to roll ever wider carpets of concrete over the bulldozed land- scape and to endow the petroleum magnates of Texas, Venezuela and Ara- bia with fabulous capaci- ties for personal luxury and political corruption.

over-Finally, the purpose of

this system, abetted by similar concentration on planes and rockets, is to keep an increasing vol- ume of motorists and tourists in motion, at the highest possible speed, in

a sufficiently comatose state not to mind the fact that their distant destina- tion has become the exact counterpart of the very place they have left The end product everywhere

is environmental tion.

desola-If this is the best our technological civilization can do to satisfy genuine human needs and nurture man’s further develop- ment, it’s plainly time to close up shop If indeed

we go farther and faster along this route, there is plenty of evidence to show that the shop will close up without our help Behind our power blackouts, our polluted environments, our trans- portation breakdowns, our nuclear threats, is a fail- ure of mind Technocratic anesthesia has put us to sleep Results that were predictable—and pre- dicted!—half a century ago without awakening any response still find us unready to cope with them—or even to admit their existence.

Transportation: “A Failure of Mind”

Lewis Mumford

(Reprinted by permission of Gina Maccoby Literary Agency Copyright © 1971 by Lewis Mumford, renewed 1999 by the estate of Lewis Mumford.)

Thirty years ago, Lewis Mumford articulated his vision as to what urban transportation should be It

is valid today, although it still remains a vision

C H A P T E R

Walking

Background

We are all pedestrians; any trip by any means includes at least a

small distance covered on foot at the beginning and end of each

journey Walking is the basic urban transportation mode that has

allowed settlements and cities to operate for thousands of years

It is still very much with us, but its role has been eroded with the

introduction of mechanical means of transportation, drastically so

in American communities, with the dominant presence of the

pri-vate automobile in the last half century

The principal transportation mode in the developing world,

even in large cities, is still walking because of constraints on the

resources needed to operate extensive transit systems People

cover long distances on foot every day and expend human energy

that they can scarcely spare Walking under those conditions is an

unavoidable chore that consumes productive capability In North

America and Western Europe, the attitude and policies are just

the opposite: walking is efficient, healthful, and natural We

should do more of it—almost everybody agrees—and some of the

current trends should be reversed Ironically, among the most

popular exercise machines in health clubs and in homes are

tread-mills that simulate walking, which could be otherwise

accom-plished with a transport purpose on the street

Admittedly, because of the size of contemporary metropolitanareas, with origin and destination points far apart, the need tosave time consumed in routine travel, and the desire for basiccomfort and avoidance of severe weather conditions, walking as

a transportation mode has limitations But the niche that it canfill is still rather large, and the opportunities are by no meansfully exploited Just the reverse is happening today, and someproactive programs will be necessary to restore reasonable bal-ance

The trend in the percentage of commuters who walk to work inthe United States1

has been negative:

of job places and commercial activities from residences), andtrips have become longer overall, but there is also the greaterpropensity to use the car for any purpose, even just to go aroundthe corner Working at home has increased slightly, but notenough by far to explain the drop in walking to and from work-places Appeals to reason and civic responsibility will not alter

the prevailing attitudes much; programs to make walking tive to individuals will have to be expanded and implemented.

attrac-The contemporary built environment in North America is notalways fully enabling toward pedestrians Not all new streetshave sidewalks, they are not always structured into coherent net-works, and they frequently lack proper amenities (good pave-ment, lighting, rest areas, etc.)

1 U.S Census data.

2 Since the 2000 U.S Census data were not yet available, information from the American Household Survey was used for 1999.

Development History

The historical review of walking could begin some 20 million

years ago, when certain animals—our ancestors—started to move

around on their hind legs.3 That would not be a very profitable

discussion; even the last 6000 years (save the last 150 years or

so) can be quickly summarized to arrive at the conditions that

prevail today

For thousands of years, settlements and urban groupings,

eventually evolving into cities, were almost entirely walking

envi-ronments Some deliveries were made by pack animals and carts,

some people were carried by one device or another, and soldiers

and chiefs liked to ride, but most movement and linkages inside

cities were accomplished on foot, even the carrying of heavy

bun-dles and parcels Cities had to be of a walking scale, and they

were—almost all of them could be easily traversed on foot within

a quarter of an hour Even the few very large ones (imperial Rome,

Beijing, Paris, London) were assemblages of neighborhoods that

each contained the daily life of the residents, including their

workplaces Extensive wheeled and animal traffic, however, was

present in the larger cities as a part of production and distribution

activities Street congestion on the narrow streets was known

even in ancient cities

The streets, often just the linear spaces left between building

lines, usually made no provisions for separate types of movement

People, carts, and animals used the same channels, mixed freely,

and were all impeded by the many activities that spilled out on the

street and have traditionally been a part of the urban scene:

ped-3 Needless to say, any dates with prehominid hominoids are uncertain Progress

was slow and gradual, and new archaeological discoveries are always making

adjustments to the dates The evolution toward erect locomotion apparently is

not yet quite complete either, judging from the fact that many of us tend to get

chronic back pain.

What is a featherless biped?

—A plucked chicken or a pedestrian.

What is a pedestrian?

—A driver who has found a parking space.

dlers, vendors of food, purveyors of various services, entertainers,musicians, preachers, children, thieves, and beggars Depending

on the organizational level of any society and the attention paid topublic works by any city administration, the streets may havebeen paved,4

but usually were not (except for major avenues), andthere may have been provisions for drainage, which can be seeneven in some of the very ancient cities Principal streets in thecities of Mesopotamia and the Indus Valley show evidence ofdrains and pedestrian lanes Significant Roman cities providedraised sidewalks along both sides of the street, leading to adjoin-ing store and housing entrances There were stepping stonesacross the vehicle channels, spaced to allow carts with wheels astandard distance apart to move along

Yet, the practice of providing sidewalks became lost for manyhundreds of years Water and liquids found their own way, notinfrequently turning street surfaces into malodorous and pestilentbogs European cities, as a rule, had no sidewalks during themedieval and Renaissance periods; they appeared in the secondhalf of the eighteenth century, at least in the more prominentcities.5

Available evidence indicates that walking on urbanstreets, up to the Age of Enlightenment, was a dangerous anddirty practice Despite certain images based on romantic nostal-gia, people walked when they had to, but not for pleasure andrecreation That became possible only considerably later, whensome protected and designated spaces were developed andopened to the public—promenades, public gardens, and parks

In the nineteenth century, sidewalks were always presentalong the sides of improved streets, with a curb and a gutter, inall the cities of the Old World, as well as in colonial towns Theprime pedestrian environments were the grand boulevards, not inParis alone.6 In American cities, the nineteenth-century “park-ways” in their early form extended the landscaped park environ-ment into the city itself and were intended for leisurely strolls andcarriage rides

4Paving means that a reasonably watertight surface is created that will keep its

shape with no ruts under the pressure of wheels, hooves, and feet, and that there will be little dust during dry periods and no mud on wet days.

5 This is a conclusion drawn from scanning many contemporary images of cities, assuming that they are reliable in the details.

6See J Cigliano and S B Landau (eds.), The Grand American Avenue: 1850–1920 (Pomegranate Artbooks, 1994, 389 pp.).

The functional purpose of a sidewalk and a curb

was to protect pedestrians from the consequences

of horse-drawn wheeled traffic, which had grown

immensely in volume and impact Crossing major

streets became a dangerous adventure, horses and

heavy wagons were frightening to most people,

and—most important—sanitary conditions on the

streets were abysmal Litter and garbage were not

collected with particular diligence, nor was the

excrement of hundreds of horses On a wet day,

ankle-deep slurry covered street surfaces, as it has

been described by some earthy contemporary

authors With a raised sidewalk in place, the tides

could be held back, a reasonably solid surface

could be provided, the adjoining property owners

could at least sweep their own frontages, and some

positive drainage could be achieved Nevertheless,

a gentleman escorting a lady was expected to walk

on the curb side to shield her from likely splashes

Gallantry aside, it was presumably easier to clean

a pair of trousers than multiple voluminous and

frilly skirts

A specific building form favorable to pedestrians

was the arcade, colonade, or loggia along the street fronts of

build-ings They are encountered in various historical periods at many

locations They were built primarily to gain more space on the

upper floors by protruding into the street, but they also offered

thereby a sheltered path for walkers (provided that the arcades

were not cluttered up with other activities), since wagons and carts

could not conveniently enter In very hot climates and in places

with extreme rainfall, they are a practical means of minimizing the

disruptions of urban life Unfortunately, today, in crime-prone

American cities, street-front arcades are sometimes banned

because of the fear that muggers may hide in their shadows

Another similar device was the passage or galleria (also called

an arcade in American English)—a building perpendicular to the

street that provides accommodation for many stores on a single or

multiple levels, with an open central circulation space The first

of these probably was the Galleries de Bois in Paris, opened in

1786 The most famous one is the Galleria Vittorio Emanuele I in

Milan (1865), but there are many others throughout Europe—

Covered sidewalk in a Renaissance city (Vicenza, Italy).

practically in every large city, since they were seen

as prestigious retail venues in the nineteenth tury America has its surviving examples as well—

cen-in Cleveland, Providence, and Los Angeles Thisconcept has emerged again in today’s planning forpedestrian spaces, as is discussed subsequently

In the second half of the nineteenth century, themovement toward park creation in American citiesresulted in attractive walking environments as

well, but for recreational purposes only The City Beautiful efforts in the very early twentieth century

extended the concept of formal boulevards, withlandscaped walkways, enhancing the prestige ofany city at that time

The appearance of modern architecture somedecades later brought with it new concepts inpedestrian space For the purposes of this discus-sion, the principal characteristic was the separa-tion of pedestrian walkways from vehicular traffic,which by that time had become a threat to safetyand, due to its speed, incompatible with the pace

of human locomotion The results were superblocks

(towers in a park), with motor vehicles kept on theperiphery and pedestrians able to follow separated paths Le Cor-busier—perhaps the most influential architect of the twentiethcentury—was a principal proponent of this design form throughhis many conceptual plans and several projects that were imple-mented, starting in the 1920s Independent walkways were notexactly a completely original idea, but they were brought into thecity fabric as a major design-governing feature Superblocks wereadvocated for lower-density neighborhoods as well (for example,Radburn, New Jersey, in 1929) Not all the efforts were attractive

or successful (for example, the massive and monotonous publichousing projects in large cities), and frequently problems withmaintenance, policing, and privacy came to the fore

Nevertheless, the separated pedestrian walkway at the locallevel leading to service facilities, institutions, and transit stopsremains a strong concept in the inventory of planning and designoptions Within the last few decades, however, a different

approach has also emerged under the label of new urbanism (or the neotraditional planning, pedestrian precinct, or transit village

Multistory nineteenth-century arcade in

Cleve-land, Ohio.

concept), which attempts to restore primacy to pedestrians within

residential and commercial districts.7 It recognizes that motor

vehicles create conflicts, but, instead of seeking to segregate

peo-ple in “safe” environments, asserts that automobiles should be

made to behave and that streets should accommodate all

move-ment, particularly walking, with no interference or dangers The

street traditionally serves all; there should be no reasons to drive

fast or irresponsibly, and, by creating reasonably high densities

and clustering activities, most destinations should be accessible

on foot Whether residents living in these districts do actually

always walk and whether developers will embrace the concept

and will be able to create a mass market remains to be seen The

new urbanists also believe that contemporary city folk want to

recapture a sense of belonging to a community and basic

neigh-borliness through walking to accomplish daily chores and sitting

on a traditional front porch facing the public street The intent is

to be applauded; social scientists, however, continue to record a

growing deliberate alienation by most residents from the public

realm and a retreat into their own private spaces (in the enclosed

car and in front of the TV set)

Similar community-building aims are expressed under traffic

calming programs as approaches toward a safe and attractive

pedestrian environment, which are outlined further in Chap 5,

Automobiles

No discussion of pedestrianization in the United States can

avoid suburban shopping centers This purely American building

form has at its core the presence of a pedestrian

space—deliber-ately designed to attract people, make them linger, and encourage

spending While these service clusters may be almost impossible

to get to on foot in low-density suburbia, once the customers park

the car, everything that has been learned about keeping people

happy and comfortable is applied here, deliberately and through

countless repetitions This encompasses weather-protected space

(usually enclosed, always at the same temperature), widths of

cor-ridors that allow show windows on both sides to be seen, plenty

of sitting and rest areas out of the main flow, colorful (if

some-7 Much literature has been generated recently regarding this concept See A.

Duany and E Plater-Zyberk, Towns and Town-Making Principles (Rizzoli, 1991,

119 pp.) and P Calthorpe and W Fulton, The Regional City (Island Press, 2001,

304 pp.).

times garish) décor with historical or popular design referencesthat are easily understood, food courts that provide for all tastesand keep customers on the premises, no interference by (not evenvisibility of) goods and maintenance operations, sufficient escala-tors and elevators if operations take place on several levels, exem-plary cleanliness, and complete security.

The ancestry of American shopping malls can be traced back tothe first half of the twentieth century, to a few examples of clus-tered stores in model developments (Roland Park, for example, inBaltimore), and particularly to the Country Club Plaza in KansasCity (1922) as the first automobile-oriented center The realmodel, however, was more likely the series of farmers’ marketsbuilt in Los Angeles in the 1930s, with off-street parking lots andcentral pedestrian circulation areas A few shopping mallsappeared before World War II, but the real boom started in the1950s, accompanying the explosive trends of suburbanizationand movement of families to open peripheral territories Thou-sands were built each year during the peak period in the 1960sand 1970s, reaching a total inventory of more than 26,000 mallsacross the country by 1990.8

The first regional mall was gate in Seattle (1950), followed by Northland in Detroit (1954).Since the 1960s, almost all the large malls have been enclosedand equipped with full climate control The size records were

[350,000 m2] of retail space, 1981) and the Mall of America

outside Minneapolis (4.2 lion ft2[390,000 m2], 1992).While shopping malls arenot specific transportation fa-cilities, they are the prime pop-ular examples of pedestrianenvironments in North Americatoday They can be seen as lab-oratories where human walking

mil-Interior of a contemporary shopping mall in Newark, New Jersey.

8 See M D Beyard and W P O’Mara,

Shopping Center Development book (Urban Land Institute, 1999, 3d ed.) and W Rybczynski, City Life: Urban Expectations in a New World

Hand-(Scribner, 1995, 256 pp.), Chap 9.

behavior can be observed and conclusions reached as to which

features are favored by real people and which are not, even if the

findings are not always encouraging (The counteraction of old

city and village centers against shopping malls to recapture lost

business by rebuilding traditional commercial cores into

pedes-trian-friendly environments is outlined under “Automobile-Free

and Automobile-Restricted Zones” in Chap 5, Automobiles.)

Another approach toward expediting pedestrian operations—

not particularly new, either—has been the creation of several

lev-els, thus giving crowds adequate space The issues associated

with multiple pedestrian levels are discussed on subsequent pages,

but successful examples are found either as entire underground

net-works or as connecting mezzanines under major street intersections

Bringing pedestrians one level up is also a possibility, but the record

with this idea is rather spotty Efforts to do that in the core areas

of London (Barbican), Stockholm, Bogota, San Juan, and other

places have largely not fulfilled expectations Second-level

sky-ways are an American invention, and they work well and are

popular as weather-protected connections in cold climates

They arefound in Minneapolis–St Paul, Rochester, and Cincinnati, and as

short linkages at many other places While they can penetrate

and enter buildings, they operate mostly as corridors, not so

much as shopping streets, and thus can be clearly classified as

components of the local transportation networks

The situation is different with underground pedestrian

sys-tems While some of them take the form of interconnected

corri-dors (as in Houston), they can accommodate activities along the

sides The most extensive network has been developed in

Mon-treal, where spacious pedestrian passageways under the street

level connect many key buildings and transit access points It is

truly an underground system Very large pedestrian networks

have been developed in the larger cities of Japan, as well as in

Seoul, Korea Extensive, albeit smaller, arrangements are found in

Toronto and New York The World Trade Center, for example, had

an extensive below-street environment with a large retail

compo-9 For a full analysis see K A Robertson, “Pedestrian Walking Systems:

Down-town’s Great Hope or Pathways to Ruin?” Transportation Quarterly, July 1988,

pp 457–484.

nent It was about to be rebuilt and improvedbefore its destruction In many instances, connec-tions from underground transit stations extend intothe surrounding blocks and offer direct entries tostores.

Localized additions to the overall pedestrian tem in high-density districts are underground cross-ing mezzanines under major street intersections.The best examples are equipped with escalators,offer a wide inventory of convenience shopping andgrazing (fast food), have public toilets, and can even

sys-be effectively used for safe loitering Vienna, don, and Prague, among other cities, have a number

Lon-of successful cases

To complete this review of options, mention has

to be made of contemporary enclosed commercialand activity spaces as a single building or combina-tion of buildings, as represented by enclosed urbanmalls They are not transportation paths, althoughpedestrian movement crosses them, and they fre-quently offer attractive alternatives to the outdoorsidewalks Indeed, the latter point can be regarded

as a criticism, because they tend to siphon lifeaway from the traditional walkways At this time it is hard tothink of any city, particularly in Europe, that would not have one

or more examples The first such project in the United States wasthe Midtown Plaza in Rochester (1962), and the more visibleexamples today are the ZCMI Center in Salt Lake City, the Gallery

in Philadelphia, Eaton Center in Toronto, the Embarcadero Center

in San Francisco, Peachtree Center in Atlanta, Water Tower ter in Chicago, and many more There are also interesting projects

Cen-in convertCen-ing historical buildCen-ings Cen-into such environments (forexample, the Old Post Office in Washington and the recentlyrefurbished Grand Central Terminal in New York)

Besides examining physical improvements encompassingpedestrian spaces and paths, there is the question of the extent towhich free human behavior, as represented by walking as arepeated daily activity by everybody, can be analyzed systemati-cally, provided for, and planned accurately through quantifiedmethods For thousands of years, pedestrian spaces happened (afew were deliberately designed), and they either worked or they

Nicollet Transit Mall in Minneapolis,

Min-nesota, with walkways and skyways.

didn’t If these environments had problems, they were

progres-sively changed; i.e., they became adjusted to needs and

expecta-tions over the years Or they were scrapped Planning and design

depended on the instincts, good sense, talent, and experience of

designers and builders Layouts and dimensions were arrived at

impressionistically Some great successes were thereby achieved,

but in most cases a trial-and-error process ensued

That situation has changed, at least to the extent that design

and planning tools have been created that bring considerable

specificity and reliability to estimates of space needs and the

structuring of safe and efficient flow paths.10

No claims are to bemade that this will automatically produce superior designs, but

any design can now be tested as to its functional adequacy and be

at least sized accordingly The principal point is that the planning

of pedestrian facilities (spaces, paths, stairs, and sidewalks) can be

supported by documentable analyses, thus bringing much more

reliability to a task that has otherwise uncertain dimensions

Types of Walking Practice

The behavior of human beings when they are in motion in public

spaces is affected by the purpose of such action for each

individ-ual at any given time As familiar as walking is to all of us,

sev-eral distinct situations can be identified

Walking Briskly

This represents the need to move expeditiously from Point A to

Point B The principal purpose is to overcome distance quickly,

and to do this by mostly ignoring all distractions and not being

diverted by other destination or action possibilities The best

example is going to work in the morning under time pressure to

reach the desk, or attending any significant event with a precise

10 The seminal work was done by J J Fruin of the Port Authority of New York

and New Jersey (published as Pedestrian Planning and Design (Metropolitan

Association of Urban Designers and Environmental Planners [MAUDEP], 1971,

113 pp.), later joined by G Benz (several articles jointly with Fruin and

Pedes-trian Time-Space Concept (Parsons Brinckerhoff Quade & Douglas, 1986)

Sub-sequently, other analysts have expanded this subfield, and it is now a regular

component of traffic engineering.

starting time The shortest time distance is chosen; safety on thepath and reliability do count, but aesthetics and human amenitiescan be largely ignored The walker in a real hurry will sloshthrough puddles, jump traffic signals, elbow others out of theway, avoid stairs, and take any possible shortcut to keep to astraight line This is definitely a form of transportation, with thetrip characteristics easily identifiable (origin and destinationpoints, time, mode, purpose, etc.) The action is rational withinthe operational context, and it is predictable as to its execution.Volumes, levels of occupancy, and speeds on connecting pathsand within spaces along the way can be estimated, if the number

of trip ends associated with origin and destination points areknown Sidewalk loading conditions and the utilization of spacescan be calculated This is the pedestrian equivalent of channeliz-ing motor traffic flow and building highway lanes (in conceptonly, needless to say) The precise pedestrian flow analysis meth-ods, outlined in following sections, are very much applicable tothis situation and give good results

Meandering 11

But we are not always in a rush People employ their senses toenjoy the surroundings, to look at interesting things that catchtheir attention, to gawk at other people, and to be a part of thestreet scene as they walk along Yes, it is still movement fromPoint A to Point B, but not necessarily in a straight line and not at

a constant speed Indeed, this type of action embodies the tiveness of being in a city, and every opportunity should be taken

attrac-to enjoy the walk and be distracted Walking should be an strained and positive experience, as long as we are not late for thenext appointment How much time any such journey will take is afunction of the time available to the walker, the interest level ofthe surroundings, and weather conditions In other words, this isnot a steady-state situation, not even for the same traveler on aregular schedule, and the level of predictability regarding theexact path and time consumed decreases If a designer lays out anexciting path for walking and meandering, will all of us move inthe same way and consume the same amount of time? Most likelynot It is a dynamic and changing situation—buildings, spaces,

uncon-11 The English language offers a few other possible descriptors for this type of

locomotion: rambling, peregrinating, sauntering, or strolling.

other people, and urban elements are seen in motion, causing

occasional slowdowns

Technical planners have great problems with these conditions,

being able at best to use statistical averages on human behavior

Tarrying 12

People are also found in pedestrian spaces and on paths with

really no urgent intention to get anywhere, but simply for the

pur-pose of enjoying the scene, meeting others, or having an outdoor

lunch A pedestrian leaves Point A, goes to a few other locations,

and quite frequently comes back to Point A He or she is a part of

the urban street theater, sometimes blocking those who are in a

hurry, consuming space and time for the best possible reasons—

personal enjoyment

We all do it when we have the time and when the weather is

good, but this is certainly not transportation Thus—reluctantly—

we have to stop further discussion of this pedestrian situation,

and leave it for urban designers and urban recreation specialists

Technical pedestrian space planners, however, have to recognize

the presence of this element as a possible and likely use of space

and facilities Systematic observations of what people do in

pub-lic spaces have brought insights on their behavior, and people’s

behavior is no longer a complete mystery.13Designs can be guided

fairly well, and it is possible to predict what will work and what

will be avoided, where people will congregate and what they will

pass by It is also possible to estimate how long persons will be

present, on the average, in such spaces

In summary, our ability to be analytically precise and

conceptu-ally purposeful with the walking mode is still limited and only

selectively reliable, particularly when pure functional linkages do

12Again, other choices for a term are available: lingering, poking, dallying,

dawdling, delaying, and—most important—loitering Unfortunately, all of them

carry a negative connotation in English, as if such activities were deplorable.

That is not so, and the rather common signs reading “Do Not Loiter” should be

used sparingly, if at all.

13 The most perceptive and productive student of these situations was William

H (Holly) Whyte, whose findings should be required reading for anybody

deal-ing with pedestrian issues Particularly recommended are his Social Life of Small

Urban Spaces (The Conservation Foundation, 1980, 125 pp.) and City:

Redis-covering the Center (Doubleday, 1988, 386 pp.).

not dominate Space-time pancy, however, can be defined,movement paths can be iden-tified, and restful places andenclaves can be structured Ratio-nality and understanding gainedfrom controlled previous and on-going research can be applied.The pedestrian situation is mostcomplex because people do notstay in marked lanes as cars do,and in many instances all threetypes of walking, as previouslyoutlined, will exist concurrently.

occu-To create any successful destrian environment, ideas andoriginal concepts generated byfirst-rate designers are still crucial Nothing very good is likely tohappen without a creative spark, but beyond that plans do not have

pe-to be guided by intuition alone The range of promising possibilitiescan be narrowed effectively and pilot projects can be tested system-atically by applying the study techniques developed recently Thedesign of pedestrian spaces, movement networks, and nodes ofconvergence can benefit greatly from a rigorous analysis

Reasons to Support Walking

Economy

The walking mode involves very little expense, either public or vate The paths themselves, usually sidewalks, are usually builttogether with normal street construction, and the specific expense

pri-is rather minimal On a local street, adding sidewalks to the othercost items would account for only a small fraction of the total cost.The pavements can be of a rather light construction since they donot have to carry heavy loads; however, they have to be strongenough to support an occasional maintenance or service vehicle.Separate walkways that traverse parks and open spaces have to beable to accommodate police cruisers and service trucks

Cost of operation is not a concept associated with the walking

mode Each person is responsible for his or her own equipment

Central pedestrian street in Munich, Germany.

(shoes, mostly), which do wear out, but it is a normal personal

expense An interesting issue is the consumption of energy A

155-lb (70-kg) person will burn 280 calories walking briskly for 1

hour14—which is a benefit in an overfed society in need of exercise,

but may be a significant consideration for undernourished

popula-tions Walking slowly, only half of that amount is consumed;

climb-ing stairs doubles the energy expenditure as compared to normal

walking

Health

As mentioned previously, an argument can be made that the

obvi-ous health benefits of this, the most basic, form of exercise should

constitute a major reason to equip American communities with

the best possible walkway systems This is a question of not only

offering a rich inventory of physical facilities, but also a matter of

structuring districts so that walking is a logical modal choice, and

the experience is safe and attractive

Availability

There is no need to wait for a transit vehicle or even to turn on

the ignition; the mode is always present and ready for use (within

reason) Most cities, particularly in the industrialized countries,

have done quite a lot to make the sidewalk network navigable to

people with mobility impairments (curb cuts with ramps

through-out), thus making the walkway system more free of obstacles to

use than any other transportation mode

Cognition

A pedestrian is in direct contact with the surrounding

environ-ment The act of walking is automatic and does not require

delib-erate attention or even too much care to avoid obstacles and

dangers The senses and the mind can be employed to appreciate

the streetscape or the landscape and to pursue independent

thought

Environmental Protection

Walking is the ultimate environmentally friendly transportation

mode (No need to worry about heat generated by bodies and

evaporated perspiration.)

14Source: NutriStrategy Web page.

Reasons to Exercise Caution

Walking, as pleasant and advisable as it might be, is not an purpose transportation mode because there are functional limi-tations

all-Distance

The human animal does become tired, rather quickly We alsohave an advanced brain that is constantly searching for the paths

of least resistance and seeks to conserve personal energy

(other-wise known as self-preserving laziness) The question that has

pre-occupied transportation planners for some time is the reasonablewalking range that people will accept, particularly Americans—well-known as car-obsessed individuals The examples range fromsome motorists who will circle a shopping center parking lot end-lessly to find a space closest to the mall, to dedicated hikers whotake great pleasure in long and challenging walks On-street park-ing spaces are deemed to be good only if they are within 200 to

300 ft (60 to 90 m) of the door

A specific planning concern is acceptable access distance totransit stations or stops on foot The general consensus today isthat a quarter mile (1320 ft; 400 m) is a range within which justabout everybody will walk; within a half mile (2640 ft; 800 m),the number of walkers may be cut by 25 or 50 percent; a few, butonly a few, will walk a mile to any destination or transfer point.Eighty percent of walking trips are less than 3000 ft (0.9 km) It

is a curious fact that residents of large cities are more likely toembrace walking than those living in smaller places New Yorkers

in particular tend to be at the top of this list Commuters from thePort Authority Bus Terminal or any of the major rail stations willreadily walk 3000 ft or more to and from their Midtown offices.Major events and festivities represent an exception to walkinglimitations—a mile is quite acceptable under those circumstances.(Any National Football League game, by definition, is a majorevent.) Even school children are pampered in this country: mostschool districts have a rule that any pupil or student is entitled to

a school bus pickup if he or she lives beyond a 1-mi radius

Speed

A human being is not particularly fast A regular walking pace is 15minutes to the mile, which may be extended to 20 minutes Thistranslates into 4 or 3 mph (6.4 or 4.8 kph) For short distances,

since walking does not involve a startup or terminal time loss, the

slow pedestrian speed does not matter, but it becomes a factor with

longer trips There are some athletes who can cover a mile in less

than 4 minutes, but even that is only 15 mph (24 kph), hardly

comparable to any motorized mode A very good marathon runner

can maintain a 13-mph speed The best that any human being has

done is 9.79 seconds in the 100-m dash (22.8 mph; 36.8 kph),

which cannot be sustained for any distance, either

Traffic engineers, who are responsible for adjusting traffic

sig-nals so that there is enough time for every pedestrian to cross a

street, are particularly concerned with velocities over short

dis-tances.15

The usual design assumption is 4 ft/s (1.2 m/s), or 2.7

mph (4.4 kph), which accommodates almost everybody Young

15Chapter 11.6 in J D Edwards, Transportation Planning Handbook (Prentice

Hall/ITE, 1992), p 396 ff.

Distances That Can Be Traveled in 30 Minutes

Express bus (suburb to central business district) 15 24.0

Private car in a badly congested city district 1 1.6

Private car moving at normal urban speed limit 12 19.3

Private car on an expressway at 55 mph 27 43.5

people walk faster, and 5 ft/s (1.5 m/s), or 3.6 mph (5.8 kph),would be workable for them However, with the presence of a sig-nificant number of elderly persons in the flow, 3 ft/s (0.9 m/s),

or 2.0 mph (3.3 kph) may be used

Some tentative studies suggest that Americans generally walkfaster than all other nationals, except the Japanese Also, that res-idents of the larger cities are more in a hurry, especially in Bostonand New York, than in smaller places This is an intriguinghypothesis, which should be tested further

Change in Elevation

People are reluctant to change elevations, because we know tively that this involves significant energy expenditure, as com-pared to level walking Thus, in any pedestrian designs for sizeableflow conditions, this aspect requires particular attention Changes

instinc-in level should be avoided if at all possible; mildly slopinstinc-ing rampsthat are not particularly prominent visually, escalators, or elevatorshave to be provided There is a natural reluctance to use overpassesand underpasses (the latter also because of safety reasons)

Weather Conditions

Adverse weather, whether it is rain, snow, high wind, or broilingsun, will reduce considerably any propensity for walking This isone of the principal reasons why indoor pedestrian environmentshave been so successful In almost all climatic regions, however,any outdoor pedestrian space or path can benefit from full or par-tial shelters, particularly because walking trips will otherwiseshift to motorized modes at certain times, thus either overloadingtransit systems or requiring them to have standby capacity Inmost instances deciduous trees are suitable additions since theirleaves provide shade, but their bare branches let the sun pene-trate in the cold months when some warmth is welcome

Carrying Goods

Again, pedestrians have limitations, including how much weightthey are able or willing to carry with them Briefcases and pocketbooks are one thing, but even shopping bags may present prob-lems Being accompanied by small children or pushing strollersare not exactly encumbrances, but such common situations dorequire attention in the design of walkways

Impaired Personal Mobility

Any community has a certain percentage of people who have

larger or smaller disabilities that will reduce the extent of their

participation in the walking mode These may be temporary, such

as a sprained ankle, or they may be permanent, such as missing

limbs There are always the very young and the very old The task

in the design of pedestrian facilities is to achieve accessibility that

allows the greatest percentage of the population to use them

Methods range from curb cuts at intersections that allow

wheel-chairs to move, to audible traffic signals that assist those with

visual impairments

Safety and Security

The technical term pedestrian–vehicle conflict refers to the

one-sided violent encounter between the soft tissues of a human body

and a large, hard, frequently fast-moving, invulnerable metal

object There are no air bags or other protective devices for the

walker; the only safeguards are to stay out of the way and to

ensure that motorists recognize the presence of pedestrians and

know that people always have priority in traffic channels when

safety issues are concerned.16

In the United States, pedestrian accident rates are

consider-ably lower than those in most other countries, but this may

sim-ply be due to the fact that fewer people walk here The rates are

too high nevertheless, no matter what they may actually be This

is a national concern, particularly if walking and jogging are to be

encouraged as an overall policy, and programs have been

devel-oped both to educate and instruct drivers and walkers and to

pro-vide physical safety elements that would minimize, if not

preclude, such occurrences There were 5307 pedestrians killed

in 1997, which represents a 43 percent decrease in the rate per

100,000 population since 1975 During this period, 13 to 17

percent of all victims of fatal accidents associated with motor

vehicles were pedestrians.17

By 2000, the fatalities haddecreased further to 4739 The largest causes were “walking,

16 A reasonably complete summary of pedestrian safety issues and programs is

found in J L Pline, Traffic Engineering Handbook (Prentice Hall/ITE, 1992), p.

19 ff.

17 U.S Department of Transportation, Fatality Analysis Reporting System.

playing, or working in roadway” and “improper crossing of way at intersection.”

road-Unfortunate associated issues are that many people do notobserve traffic regulations scrupulously when walking, andenforcement frequently tends to be rather lax with respect topedestrian behavior There are places where local residents have

a rather cavalier attitude toward “minor” regulations and will walk and ignore “Walk/Don’t Walk” signals (New York, Paris, andBangkok come to mind),18

jay-leaving aside the general urban tion in Third World cities where traffic and crossing conditionscan be quite chaotic There are other locations—primarily inWestern Europe and Japan—where rules are respected diligently.All this argues for the implementation of hard control devices(barriers, for example) that leave little discretion, even thoughthey can be seen as constraints on free choice.19

situa-Most pedestrian accidents occur when people have to crossvehicular traffic streams, as was pointed out before The numberand intensity of incidents vary widely under different street con-ditions and among various population groups For example, thereare many more accidents with cars turning left than with thoseturning right This is due largely to the impaired field of vision ofthe driver and some confusion as to who should yield the right-of-way Zebra stripes at crosswalks are highly recommended trafficmarkings, but they do not necessarily reduce accidents becausemany pedestrians ignore them, and motorists have the right toexpect that walkers will stay within the designated space A com-mon cause of serious accidents is children who run into the streetfrom between parked vehicles Elderly people also experiencehigher accident rates, presumably due to being less agile in get-ting out of the way and moving more slowly than anticipated bysome impatient motorists

The most dangerous, and most deplorable, situation is theabsence of sidewalks at all in many low-density suburban areas,

18 The author tends to brag about the two jaywalking tickets that he has received

on the streets of New York as proof of his personal independence, recognizing full well that this represents a juvenile attitude.

19 A loud controversy was generated in New York in late 1997 when Mayor liani caused short fences to be erected at high-volume pedestrian intersections near Rockefeller Center, limiting the crossing of avenues to the upstream side only This was seen as an effort to primarily expedite vehicular movement, although undoubtedly there is a strong pedestrian safety feature as well They are now grudgingly accepted.

Giu-forcing the few walkers to use the street pavement or the narrow

shoulder Joggers on busy streets are particularly vulnerable

The other dimension of concern is personal security—the

potential for criminal or threatening behavior by other people

within pedestrian environments Again, walkers, especially when

they are alone, are vulnerable in certain situations The possible

countermeasures, besides the visible presence of police, are good

lighting, clear visibility in all directions, absence of hiding places

and secluded enclaves, and—above all—many people on the

walkways at all times who maintain “eyes on the street.”

Application Scenarios

A strong argument can be advanced that a basic walkway network

should extend over the entire community where people live, work,

and use various facilities All points should be accessible on foot,

with some convenience and safety The only exceptions might be

very local streets (cul-de-sacs and loops) where motor traffic is

minimal and people have obvious priority—streets that are

for-mally or in effect traffic-calmed The desirable system, then,

would be a completely interlinked network of sidewalks and

walk-ways, with adequate dimensions and surface quality and equipped

with proper safety arrangements at all crossings of significant

vehicular movement

There will be always places within any city where the existing

or desirable pedestrian flows are sufficiently intense to apply

improvement programs beyond the standard provision of

side-walks These are opportunities to structure an urban environment

at an enhanced level of livability, convenience, and

attractive-ness Such obvious nodes are commercial and service districts,

entertainment and sports centers, stadiums, major education and

cultural institutions, transit stations, and similar venues where

people congregate These patrons deserve the means to move to

and from them on foot, which suggests the development of special

or improved walkways leading to and from the surrounding

dis-tricts and principal access points (stations and parking lots) In

many instances, interior circulation networks within special

dis-tricts and campuses are likewise candidates for careful planning

and construction of walkways

Any pedestrian plan has to recognize certain external, rather

obvious, factors that significantly influence the demand for

facil-Streets in cities serve many purposes besides carrying

vehicles, and city sidewalks—the pedestrian parts of the

streets—serve many purposes besides carrying

pedestri-ans These uses are bound up with circulation but are

not identical with it and in their own right they are at

least as basic as circulation to the proper workings of

cities.

A city sidewalk by itself is nothing It is an

abstrac-tion It means something only in conjunction with the

buildings and other uses that border it, or border other

sidewalks very near it The same might be said of streets,

in the sense that they serve other purposes besides

carry-ing wheeled traffic in their middles Streets and their

sidewalks, the main public places of a city, are its most

vital organs Think of a city and what comes to mind? Its

streets If a city’s streets look interesting, the city looks

interesting; if they look dull, the city looks dull.

More than that, and here we get down to the first

problem, if a city’s streets are safe from barbarism and

fear, the city is thereby tolerably safe from barbarism

and fear When people say that a city, or a part of it, is

dangerous or is a jungle what they mean primarily is

that they do not feel safe on the sidewalks But

side-walks and those who use them are not passive

benefi-ciaries of safety or helpless victims of danger.

Sidewalks, their bordering uses, and their users, are

active participants in the drama of civilization versus

barbarism in cities To keep the city safe is a

fundamen-tal task of a city’s streets and its sidewalks.

This task is totally unlike any service that sidewalks

and streets in little towns or true suburbs are called

upon to do Great cities are not like towns, only larger.

They are not like suburbs, only denser They differ from

towns and suburbs in basic ways, and one of these is

that cities are, by definition, full of strangers To any

one person, strangers are far more common in big cities

than acquaintances More common not just in places of

public assembly, but more common at a man’s own

doorstep Even residents who live near each other are

strangers, and must be, because of the sheer number of

people in small geographical compass.

The bedrock attribute of a successful city district is

that a person must feel personally safe and secure on

the street among all these strangers He must not feel

automatically menaced by them A city district that fails

in this respect also does badly in other ways and lays up for itself, and for its city at large, mountain on moun- tain of trouble.

This is something everyone already knows: A used city street is apt to be a safe street A deserted city street is apt to be unsafe But how does this work, really? And what makes a city street well used or shunned? What about streets that are busy part of the time and then empty abruptly?

well-A city street equipped to handle strangers, and to make a safety asset, in itself, out of the presence of strangers, as the streets of successful city neighborhoods always do, must have three main qualities:

First, there must be a clear demarcation between what is public space and what is private space Public and private spaces cannot ooze into each other as they

do typically in suburban settings or in projects.

Second, there must be eyes upon the street, eyes belonging to those we might call the natural proprietors

of the street The buildings on a street equipped to dle strangers and to insure the safety of both residents and strangers must be oriented to the street They can- not turn their backs or blank sides on it and leave it blind.

han-And third, the sidewalk must have users on it fairly continuously, both to add to the number of effective eyes on the street and to induce the people in buildings along the street to watch the sidewalks in sufficient numbers Nobody enjoys sitting on a stoop or looking out a window at an empty street Almost nobody does such a thing Large numbers of people entertain them- selves, off and on, by watching street activity.

In settlements that are smaller and simpler than big cities, controls on acceptable public behavior, if not on crime, seem to operate with greater or lesser success through a web of reputation, gossip, approval, disap- proval and sanctions, all of which are powerful if people know each other and word travels But a city’s streets, which must control the behavior not only of the people

of the city but also of visitors from suburbs and towns who want to have a big time away from the gossip and sanctions at home, have to operate by more direct, straightforward methods It is a wonder cities have solved such an inherently difficult problem at all And yet in many streets they do it magnificently.

(From The Death and Life of American Cities by Jane Jacobs (Random House, 1961, pp 29–30, 34–35), copyright © 1961 by

Jane Jacobs Used by permission of Random House, Inc.)

The book The Death and Life of Great American Cities by Jane Jacobs revolutionized thinking about

cities The key theme was a return to the traditional street as the focus of urban life where the activepresence of local residents ensures safety and a sense of community

ities People walk much more in high-density areas than in lightly

developed places, because there are more destination points

within walking range Likewise, communities with a large

popu-lation of older residents and children will show more people on

foot than those with an average demographic composition Males

25 to 54 years old are the least active participants Almost all

traffic to a corner grocery store (if it still exists) in a dense city

will be on foot; almost nobody can or will walk to a regional

shop-ping center Except for movement associated with commuting,

most walking will occur in the middle hours of the day

(The development of walkway systems with a purely

recre-ational purpose within open spaces and along water bodies is a

most desirable action as well, but it is not exactly

transporta-tion; therefore, it is not included in this discussion Similarly,

the creation of civic spaces is a subject for other analyses,

rec-ognizing that they too generate major pedestrian presence and

flows.)

Components of Walking Systems

The presumably ubiquitous pedestrian system in any community

consists of only a few rather simple physical elements, but—given

the importance of this network—a closer examination of each is

warranted

Sidewalks and Walkways

Sidewalks are normally placed within the public right-of-way on

either or both sides of the central vehicular channel, within the

marginal reserved strips, which will usually be at least 7 ft (2 m)

wide (with a 50-ft [15-m] right-of-way and a 36-ft [11-m]

pave-ment) The sidewalk itself should be at least 5 ft (1.5 m) wide,

where the governing consideration is not the size of persons, but

rather the ability of two baby carriages (or mail carts or

wheel-chairs) to pass each other In higher-intensity areas, the sidewalks

are frequently 8 ft (2.4 m) wide; in commercial districts of large

cities, they may be 15 ft (4.6 m) wide or more

Sidewalks may be placed directly adjacent to the curb, thereby

allowing some savings in construction costs, but with the

draw-back that pedestrians will be in very close proximity to moving

vehicles, and the opening of doors from parked cars may create

obstructions to pedestrians A preferred approach is to place

side-6 to12-ft sidewalk retail/café zone

6 to 10-ft pedestrian

circulation area

3 to 4-ft street tree, pole,

and utility zone

Figure 2.1 Activity street with intensive sidewalk use (green street).

walks directly or almost adjacent to the outside right-of-way line,which creates a buffer strip between the sidewalk and the curb.This strip provides a safety zone that can be landscaped It isadvisable to place utility lines under the unpaved strips, therebymaking repair and excavation less costly

The utility of sidewalks is frequently impaired by variousobstructions—sign- and lampposts, hydrants, mailboxes, busshelters, newspaper vending machines, parking meters, trees, andbenches, not to mention protruding outdoor cafes, producestands, and staircases All this may be useful and necessary, butthe effective sidewalk width will be thereby reduced (as is dis-cussed later under “Capacity Considerations”; also see Figs 2.1

to 2.3)

In most communities the responsibility for maintaining andcleaning the sidewalk rests with the adjoining property owner,even though it is located in a public right-of-way The local land-lords have to ensure that broken surfaces are repaired to precludeaccidents, that snow and debris are cleared to allow passage, thatwater does not flood the paths, and that the facility is generally ofadequate quality They may receive citations for negligence, and

8 to 12-ft sidewalk

3 to 8-ft street tree, pole,

utility and bus loading zone

10-ft curb lane bus and

parking zone

Traffic lane

Figure 2.2 Urban street with regular sidewalk.

Rest area with bench, litter bin,

and community billboard

6 to 8-ft sidewalk

3 to 4-ft street tree,

pole, and utility zone

Figure 2.3 Suburban street with pedestrian amenities.

injured parties may sue the private owners as well as the pality The owners have the duty at least to notify the appropriatecity agency about problems and deficiencies.

munici-Surfaces

The type of material used for sidewalks and the resulting surfacefinish have at least three areas of concern: ease of walking, per-manence, and visual attractiveness

The most common type of construction is poured concretewith wire mesh reinforcement It is easy to build, since not muchsubsurface preparation is necessary (no heavy loads will have to

be carried); the surface is nonslip and watertight, and the ment is durable Some shortcomings are that the surface is notparticularly interesting, the repair effort is rather extensive whenthe slabs crack or break, and the surface is hard on the feet (inevery possible sense)

pave-Bituminous blacktop pavement is usually cheaper yet, andconstruction is very easy It has a great advantage in that thematerial is somewhat resilient, thus offering very good walkingquality However, this softness (the surface may even melt undervery hot sun) makes blacktop unsuitable for real urban applica-tion—sharp heels and small hard wheels will destroy the surfacerather quickly While repairs are easy, the patched patterns andthe overall “common” appearance of blacktop walkways makethem suitable only for long recreational paths, where most userswill wear shoes with soft soles

The most attractive surfaces in general use are provided byspecial paving blocks and brick Various sizes and shapes areavailable, and interesting geometric designs can be achieved—pleasing to the eye as well as to the feet These materials are moreexpensive, and great care has to be taken in construction to main-tain the integrity and evenness of the surface Individual elementsmay become dislodged, and such surfaces become uncomfortable

to walk on because the ankles are continuously twisted A trusion of even half an inch may trip some people

pro-At the top of the line are stone slabs and polished terrazzo.Undoubtedly, they give the best impression due to the rich qual-ity of the material, and they are quite durable The problems arehigh cost and the slippery conditions that are quite likely to occurwith any moisture

Drainage and Lighting

Full and uninterrupted utilization of pedestrian facilities depends

to a significant extent on overcoming natural constraints, which

in this case are too much water and darkness The need for

drainage systems is rather obvious and unavoidable, not only to

maintain clear paths at all times, but also to ensure that no

struc-tural damage is done to the infrastructure through gradual

ero-sion or sudden wash-outs

Lighting is not a mandatory requirement, but is to be expected

anywhere that urban life continues beyond dusk It is not only a

matter of maintaining adequate and uniform illumination levels

along the entire walking system, it is also an opportunity to

cre-ate and heighten visual interest within the pedestrian

environ-ment Crime prevention is a significant consideration, with

well-lit paths and spaces to deter criminal activity (or at least to

push it to the dark places)

Traffic Control Devices and Accessibility Concerns

There should be no constraints on the movement of pedestrians,

and people should be able to proceed with no unwanted stops,

even if they have some handicaps to walking This may hold for

ideal situations only; in real life, adjustments need to be made

First, there are the many crossings with vehicular traffic that will

be present in any pedestrian network The needs and choices are

quite well understood and worked out by this time, and various

levels of controls are available—including simple stop signs for

vehicles, regular traffic signals, and controls with special phases

for pedestrians However, in American communities reminders

are needed that walking is a legitimate transportation mode that

should be encouraged and that its participants need some

protec-tion Their presence should be recognized in the timing and

deployment of signals and traffic controls, which routinely tend

to take into account the speed of cars, not of pedestrians.20

It is now the law of the land that people with physical or

men-tal impairments should receive every consideration when systems

20 Manhattan avenues, for example, have signals timed to move cars in a green

wave over long distances The experience of the author over many years shows

that a pedestrian moving at a normal pace, either with or against the traffic flow,

will face a red signal at every intersection.