Accelerated bridge construction chapter 7 ABC planning and resolving ABC issues

Accelerated bridge construction chapter 7 ABC planning and resolving ABC issues Accelerated bridge construction chapter 7 ABC planning and resolving ABC issues Accelerated bridge construction chapter 7 ABC planning and resolving ABC issues Accelerated bridge construction chapter 7 ABC planning and resolving ABC issues Accelerated bridge construction chapter 7 ABC planning and resolving ABC issues Accelerated bridge construction chapter 7 ABC planning and resolving ABC issues

309 Accelerated Bridge Construction http://dx.doi.org/10.1016/B978-0-12-407224-4.00007-1

CHAPTER

ABC Planning and Resolving

ABC Issues

7.1 Our failing infrastructure and transportation problems

America’s infrastructure is the backbone of its economy Infrastructure projects have put thousands of people to work; thus, they are one of the key factors for the long-term health and prosperity of the people in any city or state The important aspects are

1 Technical (planning, rating, design, and method of construction aspects)

2 Administrative (setting priorities on the basis of structural deficiencies and the necessary funding

aspects)

3 Research leading to developing new techniques and economic solutions.

A sustainable infrastructure almost certainly requires planning, financing, design, construction, and operation A bridge is a sensitive part of any highway system Its importance is linked to

• The network of highways it serves Major highways have priority

• The volume of traffic it carries daily Urban area bridges are more important for commerce, trade, and the overall economy

A bridge’s relative importance is considered to determine the funding allocation and its priority

In Chapter 1, the need for rapid construction and delivery of bridges was discussed in detail In Chapter 3 (Section 3.5), the important issue of accelerated bridge planning (ABP) leading to acceler-ated bridge construction (ABC) was addressed A glossary of ABC terminology applicable to all of the chapters is listed for ready reference in Appendix 2 ABC The administrative aspects for funding are addressed in Chapter 10

In this chapter, the failing infrastructure, advanced concepts of planning, the need for rehabilitation

or replacement, the use of ABC and associated financing aspects, and the scope of introducing new technology are addressed Aspects of structural deficiencies and the need for a rapid replacement and delivery system and further benefits of ABC are presented

7.1.1 Transportation problems can be resolved

Too many of our roads and bridges continue to be in a state of disrepair In addition, with population in the cities increasing, more people use urban area highways and bridges every day Heavier trucks make matters worse

The lack of smart technology, growing traffic issues, and the lack of maintenance from limited ing are to blame For example, the New York and New Jersey region transportation system is one of the largest arterial systems in the world and includes navigable rivers with many bridges and tunnels It serves automobiles and many other modes of transportation Examples are the ever-busy highways such as Interstate 95 running north to south and Interstate 80 running east to west; the multiple-lane

fund-7

Pennsylvania, New Jersey, and Ohio turnpikes; and many others Over 200 million trips are taken daily across deficient bridges in the nation’s 102 largest metropolitan regions.

We come across undesirable rush hour traffic jams daily, with the rush hours generally extending to most of the day, up to 6 days a week, with lesser intensity of traffic on Sundays It gets worse when we suddenly come across roadway warning signs such as

“BRIDGE IS OUT FOLLOW DETOUR.”

Surely, we do not want to spend part of our useful lives on the highways and consuming expensive gasoline at the same time It is not helping the environment either There were probably less stressful days with fewer problems to deal with when there were fewer motor vehicles and trains in use

7.1.2 Failure issues can be resolved with rapid delivery methods

As discussed in Chapter 6, there are numerous issues contributing to the failure of bridges, in particular those that are poorly maintained or neglected, and the failures can have an effect on the future approach

to maintenance of existing structures

In one case, an engineer improperly calculated the size of a plate that held various girders together, which failed when a large point load from construction materials stressed that joint If anything, this points to the need for better checking of engineering calculations before construction as well as inclu-sion of an engineer on maintenance and repair contracts

The Quebec Bridge is a road, rail, and pedestrian bridge across the lower Saint Lawrence River to

the west of Quebec City, and Lévis, Quebec, Canada The project has the unique disaster of failing twice (in 1907 and 1916), at the cost of 88 lives, and took over 30 years to complete

In the Washington bridge failure case, a truck that was too tall for the lane in which it was traveling struck

a steel element in a truss The nature of a truss is that when you remove an element, the truss fails

Recent collapses: Earlier, Chapter 6 showed a list of major failures in the past 10 years

A recent failure showed the collapsed I-35W bridge in Minneapolis on August 4, 2007 We can expect more disasters like this at the current levels of infrastructure investment In Chapter 5, the con-cept of hazard rating was introduced for bridges that are most vulnerable to failure from the extreme events Scour and Seismic ratings can follow the computations of hazard rating for the purpose of prior-ity and selection of repairs and replacement There is an old saying that prevention is better than cure

or that it is better to be safe than sorry

7.1.3 Magnitude of failing infrastructure

The extent of failing infrastructure can be estimated solely by

• Functional obsolescence

• Structural deficiency (SD)

• Failing or near-fallen bridges

Functional obsolescence: The following parameters causing functional obsolescence need attention:

• The deck geometry, tangent, curved, or skew

• Load-carrying capacity, provision for new live loads

311 7.1 Our failing infrastructure and transportation problems

• Vertical and horizontal clearances in the light of innovations in the truck industry

• Sight distance and approach roadway alignment

7.1.4 Bridge failures due to extreme events

An analysis of bridge failures due to construction difficulties and other common types of failures were addressed in Chapter 6 This chapter extends the analysis to extreme events and natural disasters, which are to a large extent outside of the control of human beings

and in Haiti present an unprecedented opportunity to study their effects on communities and potential exposure to earthquakes Design practices need to be developed that are in line with current seismic design criteria that some areas in the United States have begun to implement

Calamities from tsunamis: An earthquake is much more likely to become a disaster if it occurs in a populated area and when it generates a tsunami The Tohoku, Japan earthquake of March 11, 2011 combined with the tsunami and damage to the Fukushima Daichi Nuclear Power Plant resulted in per-haps one of the worst natural disasters The tsunami waves were estimated to range from 9 to 37.9 m in height, causing the majority of infrastructure destruction (with nearly 14,000 confirmed deaths, 5000 injuries, and nearly 15,000 missing) Structures built to meet current design criteria performed overall very well Damage has been primarily to infrastructure that was built with much less stringent seismic design criteria, especially in those areas with structures that did not have tsunami resistance incorpo-rated in the design codes

Planning for tsunami resistance: It is likely that future structures including highways and bridges located close to the coastal areas will take into account the huge tsunami impact force The extensive instrumentation placed by Japan before the earthquake to some extent has provided a wealth of new information that may help in planning for the future

7.1.5 Avoiding bridge failures through diagnosis and design code provisions

In a study on bridge failures performed by the author, it was concluded that most failures occurred ing construction or erection To prevent failures, engineering precautions are necessary during fabrica-tion and erection Examples of the causes of failure are failure of connections due to overstress from bolt tightening, failure of formwork, local buckling of scaffolding, crane collapse, and overload The stability of girders during staged construction and the deck placement sequence need to be investigated and temporary bracing provided Expansion bearings need to be temporarily restrained during erection Also, Occupational Health and Safety Administration rules need to be followed

dur-7.1.6 Independent watchdog societies for infrastructure health and quality

(in partnership with Slate), America’s infrastructure is woefully underfunded Its condition is severely degraded, despite continued efforts of local and state agencies to form private-public partnerships and

to manage our infrastructure in a tight fiscal climate The project details can be followed at

2013 Report Card by the American Society of Civil Engineers: On the basis of an inquiry from experts, every 4 years the American Society of Civil Engineers (ASCE) has been providing a report card that grades America’s failing infrastructure on the basis of the acceptable and unacceptable criteria for each state The grades A to D are based on the following criteria:

Capacity—Number of lanes versus smooth traffic flow

Condition—Drainage and cracks

Operations and maintenance—Road surface repairs

Public safety—Use of warning signs and lighting

Most structurally deficient bridges (SDBs) built during the 1950s and 1960s are very old and require maintenance on a regular basis Newer bridges are performing better This year the United States received a D+ Our infrastructure is crumbling with a mediocre C+ grade awarded for bridges It may

be a slight improvement from 4 years ago, but it is still pathetic Shortfalls in investment will also lead

to fewer jobs, gridlock, and an inevitable catastrophe

However, the criteria used in the past report cards from ASCE do not seem to lay an emphasis on introducing any new technology or innovative methods The evaluations in old report cards may not be directly applicable to the very important need for rapid bridge construction and delivery

At the federal and state level, the economic and environmental well-being of our businesses and families are dependent on the public and political will Our limited resources need to be mobilized against a host of challenges By its detailed investigations, ASCE seems to recommend to its members and professional forums that they deliver a message to use the goodwill of the elected legislative Public and private stakeholders need to encourage their elected representatives to revitalize transportation infrastructure and operations in the 50 states This is possible only by outreach, newsletters, and edito-rial comments

As a panel member of the ASCE 2014 Report Card Committee for Pennsylvania bridges, the author has investigated the following measures that would be applicable to most states The reason that the bridge category is performing slightly better than the highways, etc., is due to the following:

1 New technology being introduced (e.g., integral abutments, higher concrete strengths, and

high-performance steel [HPS] leading to longer spans)

2 Introduction of spliced P/S concrete I-shaped girder designs (longer spans from 225 to 270 ft

possible, competitive with steel spans)

3 Use of hybrid and composite girders.

4 Introduction of geosynthetic reinforced soil (GRS) abutments similar to those used by the Ohio

Department of Transportation (ODOT)

5 Introduction of the NEXT Beam (precast concrete beam system).

6 The “Spliced Prestressed Concrete Girder Standards” drawings developed by the Central Atlantic

Bridge Associates (CABA) and Janssen & Spaans Engineering The Spliced Prestressed Concrete Girder used in a continuous unit is currently only permitted for tangent structures The minimum length of a continuous unit to use this product is 500 ft, and the maximum is limited to 1510 ft

7 Introduction of precast substructure (CABA standards and guidelines).

8 The use of Load and Risk Factor Design (LRFD) software for substructure (such as ABLRFD,

PAPIER) and for superstructure design (such as STLRFD, PSLRFD, etc.) has helped

9 Pennsylvania passed legislation in September 2012 to allow the P3 type of contracting to provide

funding The Pennsylvania Department of Transportation (PennDOT) is developing an Asset

313 7.1 Our failing infrastructure and transportation problems

Management plan (required under MAP-21) and using a policy and data-driven, based approach to resource allocation and utilization The ability to predict asset needs and asset conditions for various funding levels and program policies (i.e., improvement vs preservation vs maintenance) will be essential for strategic and tactical decisions

performance-The ASCE documents the shortcomings of investments in its series of reports, Failure to Act performance-The

investment shortfall is forecast to be $1.1 trillion by 2020, increasing to $4.7 trillion by 2040 The deterioration of infrastructure has direct and indirect costs, sometimes measured in human lives A systemic failure naturally presents an incredible direct cost There are plenty of infrastructure prob-lems The number of concrete structures put in place in the 1950s and 1960s that will need repair and upgrade in the near future is most likely to be gigantic

Several fundamental guiding principles need to be developed:

• Exercising leadership and management in decision-making processes at all levels

• Using an integrated systems approach using modern technology

• Quantifying, communicating, and managing risks

• Adapting critical infrastructure in response to the dynamic conditions and practice

SD: It is important to investigate the internal SD in the structure Structural deficiencies include one

or more of the following:

• Low structural capacities

• Lack of redundancy in the structural system

• Poor condition of superstructure and deck

• Poor condition of substructure

• Fatigue and fracture of beam connections

• Bearings malfunction

• Corrosion of steel and concrete

• Hydraulic inadequacy: Environmental or Coast Guard (CG) concerns may push the rehabilitation versus replacement decision in the direction of rehabilitation, whereas hydraulic inadequacies and poor stream alignment may push the decision toward replacement

• Soil conditions: Any signs of foundation settlement may push the decision toward requiring the replacement of structure

• Seismic vulnerability: If an existing bridge does not meet current American Association of State and Highway Transportation Officials (AASHTO) or state design specifications, then seismic retrofit needs to be considered

• Substandard geometry: The factors to consider in planning and improving the substandard

geometry are

• Design speed

• Clearances: vehicular/navigational

• Substandard deck geometry

• Lane and shoulder width

• Maximum profile grade

• Minimum horizontal radius

• Super elevation rate and cross slopes

• Stopping sight distance to prevent accidents

• The level of service such as lighting, deck drainage, and variable message signs

A combination of the above factors as reported by inspection reports and rating studies can lead to weight restrictions; shutdown of the bridge; and, in some cases where detour is not feasible, shutting down the highway.

7.1.7 Status of SDBs in the United States

It will be noted that the different types of ratings help to identify SDBs The data are used for ing priority for fixing and fund allocations Table 7.1 shows the highest percentages of deficient bridges

establish-in Pennsylvania and Oklahoma

Among others, the following states are taking measures to resolve the deficiencies in their bridges and coming up with the required funding

approxi-mately 67,000 of the United States’ 605,000 bridges are considered structurally deficient The SAFE Bridges Act, introduced in the U.S House of Representatives, would provide $5.5 billion to begin to reduce the backlog of the more than 150,000 structurally deficient and functionally obsolete bridges across the country Transportation for America, a national safety advocacy group, found that Maine had the ninth highest percentage of SDBs in the county Commercially available retrofitting technologies exist in the United States

Although the nation as a whole received a C+, the 2013 Report Card for America’s Infrastructure from ASCE gave Maine a C– for the condition of its bridges The report found that the Maine Department

of Transportation (Maine DOT) was responsible for 2772, or 70%, of known bridges in the state, only

Table 7.1 Increasing Number of SDBs in the United States

State Approximate Percentage Deficient (Rounded)

315 7.1 Our failing infrastructure and transportation problems

205 of which were more than 80 years old Transportation officials estimated that 288 bridges would be

at risk of closure or weight restrictions within a decade

• After the I-35 Bridge in Minneapolis, MN, collapsed into the Mississippi River in 2007, killing 13

people and injuring 145, Maine DOT assembled a panel that released a report Keeping our

Bridges Safe

• The older concrete slab bridges were not designed to carry new truck loads, and if reinforcement

is not provided, more of them will need to be posted with weight limits

Massachusetts: For details on Massachusetts bridge issues, refer to the following websites:

• http://www.massdot.state.ma.us/planning/Main/StatewidePlans/StateTransportationImprovementProgram.aspx

• http://www.boston.com/yourtown/news/downtown/2013/08/state_250m_project_will_let_drivers_travel_at_normal_highway.html

New York: New York bridges also have a high estimated cost of rehabilitation at nearly $9.4 billion

Pennsylvania: The Pennsylvania Turnpike, our nation’s first superhighway, has always had a toll The

Turnpike Commission has to pay the money they collect to PennDOT for other projects because of Act

44 Because of a lack of toll collection on other Pennsylvania roads, the Pennsylvania Turnpike Authority may have to cut funding on its own rehabilitation projects to maintain funding to other departments

Ohio: ODOT has reduced the number of SDBs, but more and more bridges are aging into the

“at-risk” category Â, the designator for bridges before they become “structurally deficient.” Most tures and infrastructure systems were built before current design methods were developed The struc-tures, lifelines, and transportation systems are deteriorating

struc-Oregon and Washington: An earthquake of magnitude 9 on the Cascadia subduction zone will

affect all communities along the Oregon and Washington coastline Many earthquake-prone areas in the United States did not adopt seismic design until recently (e.g., Oregon adopted seismic requirements in 1994) Lack of seismic resistance is a common problem for all old bridges It may be more economical

to replace them to meet new seismic design criteria than to retrofit them

In May, a bridge over the Skagit River in Washington collapsed, again raising concerns about the bling infrastructure in the state The bridge was built in 1955 and is one of many aging bridges in the state

crum-Local governments: They perform periodic emergency response drills to identify gaps in their

emergency plans Where applicable, tsunami evacuation routes need to be identified and marked to aid

in the event of a tsunami

Plan of action: New technology and innovative methods such as ABC need to be introduced Design

software may be updated to include construction and erection loads The benefits will be in improved quality, improved resilience, and overall cost reduction for the new bridges The following are some of the actions that will help to attain these benefits:

• Use of structural health monitoring (SHM) by using remote sensors for bridge management

• Bridge management systems (BMSs) can use laser techniques to evaluate scour depths at bridge foundations

• Partial ABC can be upgraded to full ABC by prefabrication and design-build (DB) contracts Construction will not be delayed because of bad weather with factory production There will be reduced indirect costs resulting from fewer traffic jams and detours

• Use of Federal Highway Administration (FHWA) software for life-cycle cost analysis will also help in reducing huge maintenance costs being incurred by the agencies.

• Bridges on rivers need to have protection against peak floods Modern countermeasures designed using the latest standards for the Hydraulic Engineering Circular (specifically, HEC-18 and HEC-23) need to be installed

• For hydrologic analysis, the use of U.S Geological Survey (USGS) software such as StreamStats

in place of the outdated TR-55 will greatly help in making the bridges safer and reduce costs of scour countermeasures Also Army Corps of Engineers has replaced HEC-2 hydraulic analysis software with the more powerful HEC-RAS Scour analysis can be performed by HEC-RAS

• Introduction of long-span segmental construction on wide rivers (a recent example is the Edison Bridge segmental construction in New Jersey)

• Increasing the limits of splice locations in new precast girders

• Introduction of WOLF-type precast girders

• Repair of military bridges (existing bridges on military routes need to be checked for new military live loads)

• Energy dissipation: Technologies such as base isolation systems and various damping and energy

dissipative devices are used to reduce seismic effects and the resulting structural damage to structures

• Wireless structural monitoring sensing systems: For rapid information retrieval and damage

assessment, new remote sensing techniques, including nanolevel and bioinspired sensing devices for more robust damage detection, are being developed

• Laboratory testing of models: Over the past 10 years, the Network for Earthquake Engineering

Simulation has performed the systematic testing of scaled structures and structural components enabling validation of theoretical models

• Shake maps: Rapid mapping dissemination after an event is now available after every earthquake

in California because the shake maps produced by USGS can be used by local and state ments in their planning for response and recovery operations

• Federal Emergency Management Association (FEMA) software: The software tool HAZ-US

developed by FEMA for multihazard loss estimation is also being used by state and local ments to estimate potential losses

• There is a need to develop approaches to maintain or rehabilitate the resilience of the existing structures by managing extreme events It is hoped that these approaches would be able to extend the service life of the existing inventory of bridges and highway structures

• Substructures: They would require methods for strengthening the piers and abutments for extreme

events ABC will improve worker safety, quality, and constructability

7.2 Planning bridges on new routes and replacements on existing routes

thorough-317 7.2 Planning bridges on new routes and replacements on existing routes

Arterial: Thirty-three percent of bridges serve interstate or arterial highways

Collector: Twenty-seven percent of bridges serve collectors Collectors collect and distribute traffic between arterials and local roads They are typically two-lane roads and provide for shorter trips at lower speeds

Local: Forty percent of all bridges serve local roads

7.2.2 Types of traffic

Each type has special requirements for varying live load impacts

• Type 1: Highway bridges carrying vehicular traffic

• Type 2: Transit and railroad bridges carrying train traffic

• Type 3: Pedestrian bridges

• Type 4: Equestrian bridges

• Type 5: Airport bridges carrying aircraft

7.2.3 Feasibility studies

As part of planning of medium- and large-span bridge projects, it is customary to perform a feasibility study

• It ensures constructability

• It prevents a future change in design and thereby delay of the project

• It leads to preliminary member sizes and accurate cost estimation

• Feasibility study data and preliminary calculations can be used at the detailed design stage by another team

This approach helps with removing any unexpected problems (e.g., unsafe soil conditions) before any funding can be approved

7.2.4 Responsibility of asset ownership and the “whose baby?” issue

Ownership governs individual design criteria, and the owners develop procedures for maintenance or reconstruction In the United States, bridge ownership breaks down in roughly the following way:Local government owned: 51%

State government owned: 48%

Federal government owned: 1%

7.2.5 Geometry

Structural analysis is based on bridge geometry:

Type 1: Normal right angle plan

Type 2: Skew plan

Type 3: Horizontally curved plan

Type 4: Bridge on curved vertical alignment

Deck surfacing is made of timber, concrete, or steel deck

approaches, and ramps A typical travel lane is 12 ft wide For staged construction, it can be less than

12 ft (but not less than 10 ft) The minimum width of a vehicle is 4 ft between wheel centers and ally 6 ft overall A vehicle with a wide load is required to display the warning sign “WIDE LOAD.”The minimum width of a shoulder is 3 ft between the edge of the travel lane and the concrete barrier and less than 3 ft between the edge of the temporary lane and the concrete barrier during staged con-struction Small shoulder widths serve as buffer zone to avoid accidents The standard shoulder width

gener-is 10 ft, with a minimum width of 6 ft for emergency

For safety reasons, a sidewalk is generally provided on both sides of the roadway Even during staged construction a provision for temporary pedestrian bridge and utility support is usually required Sidewalks are elevated by 8 in from the outer edge of the shoulder or the outer edge of the lane For heavy traffic, a safety fence is required The typical width of a sidewalk is 5 ft

Entry or exit ramps connect two levels of traffic moving approximately at right angles For safety reasons, entry and exit ramps are located adjacent to the right lane, which carries slower traffic

A ramp has traffic moving in a single curved direction whereas a bridge has traffic moving in both directions An acceleration lane is for transition from a slow-speed entry ramp merging into fast-moving traffic Likewise, a decelerating lane serves as a transition between a fast lane and a slow-speed exit ramp

7.2.6 Structural systems

The design of a bridge is related to the structural system Beam, truss, and arch configurations may be used for medium span lengths:

Type 1: Slab bridge

Type 2: Through bridge

Type 3: Slab-beam bridge

Type 4: Truss bridge

Type 5: Arch bridge

Type 6: Cable-stayed bridge

Type 7: Segmental bridge

Type 8: Suspension bridge

7.2.7 Parameters for the selection of bridges and span classification

The minimum single span for a bridge is 20 ft, below which a culvert is normally used

Pedestrian bridges with lighter live loads can be smaller in length than 20 ft

Single spans: In practice, most bridges are a single span over narrow rivers or narrow roads with two

or three lanes

Continuous spans: Piers are needed over wide rivers, highways, or valleys Continuous bridges have the added advantages of redundancy, which generates increased resiliency against failure

319 7.2 Planning bridges on new routes and replacements on existing routes

Span length: Construction issues are based primarily on span lengths For practical considerations, the selection of bridge types may be governed by the span length The earlier rule of thumb was short span is less than 50 ft, medium span is 50–200 ft, and long span is greater than 200 ft

On close examination for planning purposes, span lengths can be reclassified as follows:

Small span (20–40 ft): Examples of the types of superstructure used are

• Bridges with steel stringers (Note: They have relatively higher life-cycle costs for small spans

when compared with using timber or modern precast concrete bridges.)

• Reinforced concrete slab and T-beams

• Precast prestressed cellular decks

• Timber bridges using glulam or sawn timber

• Prestressed concrete adjacent and spread box beam bridges

Medium span (40–120 ft): Examples of the types of superstructure used are

• Prestressed concrete adjacent box beams

• Spread box beams

• Steel girder bridges

Long span (120–240 ft): Examples of the types of superstructure used are

• Steel girder bridges (50W or hybrid 70W and 50W grades)

• Steel deck and through trusses

• Prestressed concrete arches

Very long span (over 240 ft): Examples include

• Steel arches

• Prestressed concrete segmental boxes

• Cable-stayed bridges

• Suspension cable bridges

Pier types

Multiple bents and flared caps are aesthetically pleasing Common shapes include

• Solid wall

• Hammerhead

• Multiple column bent

• Modern types are

• Multiple pile bent

• Integral pier

Foundation types

• Spread footing

• Drilled shaft or caisson wall

• Pile foundation (end bearing or friction piles)

• Steel H pile or W sections

• Steel pipe pile

• Concrete pile or steel-encased concrete pile

• Prestressed concrete pipe

• Steel sheet piles

For the selection of the foundation, the expertise of a geotechnical engineer will be used

The Geodesign concept incorporates the latest technologies, such as geographic information tems Model Builder, building information modeling, robotics, and gaming, to capture, manage, ana-lyze, and display detailed geographic information These technologies and applications allow professionals to come up with master plans and designs that more closely adhere to sustainable prin-ciples (see http://www.montgomerynews.com/articles/2013/10/07/roxborough_review/news/doc5252

An example of widely used partial ABC using conventional design-bid-build (DBB) is shown in

Figure 7.1

FIGURE 7.1

Single-crane lifting of precast, prestressed concrete box beam (designed by author for Lumberton bridge).

321 7.3 Role of government agencies in maintaining infrastructure

7.3 Role of government agencies in maintaining infrastructure

7.3.1 The administration of infrastructure and asset management

Administrative responsibilities: If correctly diagnosed, failures lead to improvements in design and maintenance procedures In addition to the regular update of design codes, it is also important to under-stand the role of oversight and to ensure that adequate funding is provided by the federal and state agencies Because potential failures are a hazard to public safety, they fall under the jurisdiction of federal government agencies such as

FHWA: FHWA is the main agency for oversight of highways with regard to maintenance, safety, reestablishing mobility, and reconstructing bridges after a catastrophic failure

The National Transportation Safety Board (NTSB): NTSB is the entity that usually investigates the causes of bridge failures It has the general authority under 49 U.S.C §1131 to investigate selected highway accidents in cooperation with state authorities

FEMA: An agency of the U.S Department of Homeland Security, FEMA oversees disaster tion, preparedness, response, recovery, and education of engineers Federal highway funding programs are the main source for funding of bridge repairs FHWA’s Emergency Relief (ER) program is also administered through the state departments of transportation The ER program provides funding for bridges damaged in natural disasters or that were subject to catastrophic failures The program provides funds for emergency repairs immediately after the failure to restore essential traffic and for long-term permanent repairs It also uses innovative contracting to accelerate the rebuilding of any damaged federal-aid highway facilities

mitiga-Interstate preventive maintenance: These projects cater to

• Accidents caused by deficiencies

• Corrosion prevention by painting

• Sealing of cracks

• Deck joint repairs

• Highway capacity improvement

The CG and the Army Corps of Engineers (COE): They have the responsibility of clearing and ing the waterways after floods or a vessel collision The CG is the authority that will declare the river safe for navigation once river debris has been removed The COE is the agency responsible for clearing federal navigation channels and assisting in the removal of river debris with a barge-based crane operation.Examples of special situations for funding are

• The need for providing scour countermeasures

• Seismic retrofit of bearings and connections

• Condition of the bridge, according to the Bridge Management System Coding Manual,

Publica-tion 100A For example, in Pennsylvania, a condition rating of 6 or less would require the need for rehabilitation

• If a bridge is structurally deficient or functionally obsolete, with a sufficiency rating of 50, then it may receive Federal Critical Bridge (FCB) funds for replacement or rehabilitation

• If a bridge is structurally deficient or functionally obsolete, with a sufficiency rating between 50 and 80, then it may only receive FCB funds for rehabilitation

• All of the deficiencies and problems listed in inspection reports must be addressed and resolved

The Federal-Aid Highway Program is funded by the Highway Account of the Highway Trust Fund (HTF) These are several large “core” formula-driven programs through which highway funds are apportioned to the state departments of transportation, including the

• Interstate Maintenance Program

• National Highway System

• Surface Transportation Program

• Congestion Mitigation and Air Quality Improvement Program

• Highway Bridge Replacement and Rehabilitation Program (HBRR)

• Discretionary programs under the control of FHWA or earmarked directly by the U.S Congress, such as the Safe, Accountable, Flexible, and Efficient Transportation Equity Act, a Legacy for Users

States can “flex” funds from other Federal-Aid Highway Programs to increase spending on bridges

In addition, there is nothing to prevent a state from spending its own funds on bridge projects beyond the minimum local matching share

or rehabilitation of structurally deficient or functionally obsolete bridges HBP is also referred to as the HBRR HBRR is the primary source of federal funds for replacement, reconstruction, and capital main-tenance HBRR funds are apportioned to the states by a formula based on each state’s relative share of the total cost to repair or replace deficient highway bridges Plans for the spending of these funds are under the control of the state departments of transportation These funds are usually not spent on new bridges, but they are available for the following:

• Systematic preventative maintenance

• Rehabilitation to restore structural integrity or to correct major safety defects

• Replacement of low-water crossings, and bridges made obsolete by certain COE projects and not rebuilt with COE funds

• Painting, seismic retrofitting, antiscour measures, and deicing applications

• Total replacement of a structurally deficient or functionally obsolete highway bridge with a new facility constructed in the same general traffic corridor

A funding application report will address the following issues:

• Geometry, number of lanes, horizontal and vertical clearance

• Deck condition: Concrete strength, cracking, corrosion detection by half-cell method, tions, spalls, salt content above and below reinforcement layers, and air content

• Deck drainage, substructure drainage, and drainage disposal

• Safety railings

7.3.2 The role of state departments of transportation

Although the Federal-Aid Highway Program provides federal money to highways and bridges, the money itself is normally under the control of the states The state departments of transportation (DOTs) have to comply with detailed federal planning guidelines on where and how the money will be spent

323 7.3 Role of government agencies in maintaining infrastructure

The options available to each state are as follows:

• Increase funding to perform immediate repairs

• Implement weight restrictions

• Install high-tech sensors and train additional inspectors

• Close down some lanes, if feasible

• Close down the bridge adversely affecting travel, trade, and commerce

Funding can be increased by

• Increases in HTFs

• Issuing bonds and taking out debts

• Raising gasoline taxes

• Hiking tolls on roads and bridges

• Shifting funds from other nontransportation allocations

7.3.3 Project production process

Scoping is the first major stage of the project in which most important decisions are made The end products of this stage are

• Project objectives

• Design criteria

• Feasible alternatives

• A reasonable cost estimate

• To identify key environmental issues (e.g., wetlands, endangered species, protected streams, contaminated soil, asbestos, lead-based paint, noise, etc.)

The information needs to be assembled and analyzed in this stage It must be of sufficient detail to demonstrate that the project is defined by these “scoping products.” Analysis should show that the scope of the project is appropriate Only then should the next stage of project production be undertaken

The scope of work: This applies to the following aspects:

• Life-cycle cost evaluation

• Maintenance and protection of traffic (MPT)

• Hydraulic and scour studies

• Seismic retrofits

• Environmental considerations and acquiring permits

• Performing value engineering for optimum project cost

The following outlines some of the major steps in scoping for a rehabilitation project:

Addressing specific deficiencies: The scoping document may also serve as a design approval ment It should include the following information:

• Obtain and examine bridge inventory, load rating data, and the latest inspection report ing the overall condition of the bridge and the specific condition of the major structural elements,

(consider-the year constructed, design loading, etc.); this can provide clues to (consider-the potential serviceability of

a rehabilitated structure

• Identify geometry, materials used, and details that may limit potential alternatives

• Obtain and examine record plans; structure width; and type of construction, materials used, and fabrication methods used

Verifying documented information includes the following steps:

• Verifying data to ensure that the information in the bridge inventory and inspection system and on the record plans is accurate

• Visiting the project site: This is not meant to be an in-depth bridge inspection, but rather a

verification visit to assist in a feasibility assessment

If applicable, evaluating the hydraulic adequacy of the structure includes the following steps:

• Identifying susceptibility to flooding, scour, and damage from floating ice and debris

• Performing a hydraulic assessment

• Performing some preliminary engineering activities before closure of scoping activities

• The technical activities for this phase are focused on feasibility, including a list of reasonable alternatives and their cost estimates

• General considerations that help define the feasibility of each alternative are required

Determining reasonable costs and a schedule for the most feasible alternate includes the following steps:

• Providing project-specific programing information

• Comparing general requirements of work to other projects of similar size and type and estimating

a reasonable cost for work

• Preparing an approximate schedule

Summarizing recommendations of scoping activities includes the following steps:

• The information gathered and the conclusions reached through these activities should be presented

in the project’s scoping document

• Any unfeasible alternatives should be eliminated

7.4 Engineers meeting the need to replace or rehabilitate bridges

7.4.1 Assessment of the condition of a structure

The following documents are required for condition evaluation:

• In-Depth Inspection Report

• FHWA Recording and Coding Guide for the Structure Inventory: The old Structure Inventory and

Appraisal sheet codes for condition evaluation or shutdown of the bridge have now been replaced

by the Pontis data sheet

325 7.4 Engineers meeting the need to replace or rehabilitate bridges

7.4.1.1 Use of AASHTOware program

The AASHTOware Bridge Rating replaces the former Virtis program The analytical software allows users to perform bridge load ratings that are indispensable for determining maintenance needs, ensur-ing public safety, scheduling retrofit or replacement elements, and for assessing overload permits Bridge Rating provides highly accurate load rating techniques and calculations

Pontis (now known as AASHTOware Bridge Management) is a bridge management software tool

It is a data application, relying on collected cost data and condition data of bridge elements (beams, piers, railings, etc.)

AASHTOware Bridge Management was developed during the early 1990s AASHTO incorporated the Pontis program into the AASHTOware program and Pontis 4.2 and 4.3 were issued to the licensees

in 2003 These data are analyzed to arrive at the optimal long-term preservation and improvement cies for a network of bridges

poli-The software now includes multimedia capability, supports links to photos and drawings, the ing of data in metric or English units, and enhanced security Pontis 5.1.2 improved the utility of agen-cies’ bridge inspection data and laid the groundwork for the next generation of AASHTO’s Bridge Management software requirements by ensuring data are in the correct format It prepares agencies’ inventory data for multiobjective risk assessment, tradeoff analysis, and deterioration modeling tools in Pontis 5.2 (which is currently under development)

enter-AASHTOware Bridge Management information is available at

The rehabilitation of highway structures other than bridges is also considered equally important These include bridge approaches, sign structures, railings, parapets, fences, noise barriers, and culverts; each is a subject in itself

Rehabilitation process: FHWA rating criteria are generally used However, newer monitoring ods have emerged using remote sensors and robotics Twice yearly, yearly, or as needed, inspection reports serve as the eyes and ears of the design engineer Recommendations coming from the field assessment are evaluated by rating analysis programs Alternatives based on repair methods and cost consideration are studied before preparing rehabilitation designs and drawings

meth-7.4.2.1 Steps required for rehabilitation

As discussed in earlier chapters, necessary steps for rehabilitation are emphasized

• Field inspection and SHM followed by preparing an inspection report

• Condition and sufficiency ratings: Compute the condition rating and sufficiency rating for funding

approval

• Analysis and load rating (inventory and operating ratings) Additional ratings for extreme loads such as scour and seismic vulnerability may be required

• Preparation of a rehabilitation report.

• Implementing diagnostic design procedures

• Selecting methods of retrofit, rehabilitation, or replacement

• Contract documents: Preparation of contract documents and selective reconstruction.

7.4.2.2 Components of bridge to rehabilitate

• Decks, deck joints, or bearings are subjected to deicing salts and constant wear and tear and need the greatest attention

• Usually the substructure is to some extent overdesigned and is less likely to need repairs, except for repairs resulting from erosion or earthquakes

Choice between rehabilitation and replacement: With thousands of bridges to be fixed, the criteria are

• Economics: Replacement is expensive.

• Inconvenience to the public during reconstruction: It causes interruption in service during the

construction period

• Sentimental/historical reasons can discourage replacement

• Environmental concerns and permit requirements will be greater for new bridges, especially those with four or more lanes

• A sufficiency rating, diagnosis of deficiencies, and cost-benefit analysis need to be performed to determine the course of action

7.4.3 Improving bridge management

When starting a bridge rehabilitation/replacement project, identifying the causes for existing tural deficiencies, functional obsolescence, and bridge failures is an important step A review of the issues addressed in previous report cards and any implementations completed or underway so far also need to be discussed Priorities in selection criteria for rehabilitation/replacement also need to

struc-be examined

Monitoring using nondestructive testing (NDT), SHM , and remote sensors: The potential exists for

the development of early problem detection and warning systems and the use of NDT facilities mentation of effective monitoring systems results in reduction of manhours and development of opti-mal inspection and repair schedules

Imple-Effective monitoring systems can

• Assess long-term performance and increase system reliability

• Improve the credibility of inspections and subsequent ratings through less subjective data

• Improve uniformity of data, enabling the development of better decision-making tools

• Improve and augment visual assessment and provide early detection and warning

rehabilita-tion reports for emergency repairs, which should be implemented as soon as possible The following course of action is adopted:

1 No reconstruction option should be dismissed without good reason The scope of work, type of

design, construction effort, and cost should be evaluated before a decision is made

327 7.4 Engineers meeting the need to replace or rehabilitate bridges

2 In extreme cases, the bridge may be shut down indefinitely A temporary detour is followed.

3 In other cases, some lanes may be closed down to reduce risk of failure by reducing live loads.

4 A partial detour in one direction only may be used.

5 The client may have emergency repair funds through which immediate repairs are possible

Design exceptions as required need to be approved by the state

Inspection classification: NBIS and live load and sufficiency ratings serve as the criteria for ing bridges for replacement or rehabilitation This requires inspection data For inspection purposes, many highway agencies have the following classifications:

• Abandoned: A bridge that once satisfied the bridge inventory definition, but it is now permanently

closed

• Closed: A closed bridge that once satisfied the bridge inventory definition, but it is now

temporar-ily closed for any reason except collapse Secondary uses such as pedestrian traffic may be

allowed

• Collapsed: A bridge that once satisfied the bridge inventory definition, but it is now closed

because of collapse

• Deleted: A bridge that has been deleted from the inventory.

• Inventory: A bridge included in an inventory file when it carries moving loads.

• Temporary: A bridge that is used to maintain traffic during a modification or replacement.

Results from a study on infrastructure health conducted by FHWA, in coordination with AASHTO, are now available online in a series of four reports

“The study’s goal was to define a consistent and reliable method to document infrastructure health, focusing on bridges and pavements on the Interstate Highway System,” according to FHWA The goal was to develop tools to provide FHWA and state transportation agencies with key data that will produce better and more complete assessments of infrastructure health nationally

For this study, definitions of good, fair, or, poor relate solely to the condition of a bridge or ment and do not consider other factors such as safety or capacity Separate tiers of performance mea-sures that can be used to categorize bridges and pavements were then evaluated Tier 1 measures are considered ready for use at the national level whereas Tier 2 measures require further work before being ready for deployment

pave-Performance measures for bridges included SD ratings (Tier 1) and structural adequacy based on National Bridge Inventory (NBI) ratings (Tier 2):

These measures were evaluated on I-90 in Wisconsin, Minnesota, and South Dakota The I-90 ridor runs for 874 mi, with average annual daily traffic ranging from approximately 5000 vehicles to 90,000 vehicles Evaluations were done using Highway Performance Monitoring System and NBI data

cor-as well cor-as data collected by the FHWA project team and provided by the participating state highway agencies State information included documentation of their systems, processes, and corridor inventory

The good, fair, and poor analysis for bridges proved to be a viable approach, with NBI data ficient for the performance management assessment However, a bridge’s SD status was not as easily incorporated into the analysis The study report notes that a measure of structural adequacy that is based on NBI ratings would be a viable supplement to SD status as a national measure of bridge condition, although “implementation would require developing a general consensus on its definition.”

suf-As part of the study, a sample health report was prepared for the pilot corridor This report uses several metrics to assess the overall health of a corridor, including the good/fair/poor measures, age, remaining service life for pavements, and traffic volumes The assessment would enable FHWA to examine corridor health across multiple states in a consistent manner To download the pilot study

report, Improving FHWA’s Ability to Assess Highway Infrastructure Health (Pub No

FHWA-HIF-12-049), go to www.fhwa.dot.gov/asset/pubs/hif12049/hif12049.pdf

FHWA and AASHTO presented the study results to senior-level state transportation agency sentatives at a national meeting held October 13, 2011, in Detroit, Michigan To view the national meeting report, which summarizes discussion about the recommended condition ratings and health reporting, visit www.fhwa.dot.gov/asset/health/workshopreport.pdf

repre-7.4 4 Structural options

Planning and design procedures for replacement are covered by LRFD Design Specifications and will only be briefly discussed in this book General considerations include various interdisciplinary approaches, including extensive planning considerations, such as:

• Funding and cost

• Relocation of utilities

• Functional requirements

• Right of way

• MPT and staged construction

• Improving soil conditions

Other considerations are as follows:

• Use of standard geometry, alignment, and profile

• Vertical and horizontal clearances

• New technology and innovative methods

• Future maintenance and inspection access

• Development of rehabilitation and replacement schemes by performing value engineering

The AASHTO Standard 16th Edition and AASHTO LRFD specifications address the following standard issues for bridges to remain functional:

1 Design speed limit

2 Standard lane and shoulder width

3 Maximum profile grade

4 Minimum horizontal radius

5 Super-elevation rate and cross slope limits

6 Stopping sight distance and K value

329 7.4 Engineers meeting the need to replace or rehabilitate bridges

7 Clearances, vehicular/navigational

8 Level of service

7.4.5 Maintenance versus replacement

The life-cycle costs and rehabilitation efforts are greater for the superstructure components because they are subject to greater wear and tear from traffic whereas the substructure is less affected by this Replacement can apply to a component or to the entire superstructure:

• Parapet replacement

• Deck overlay replacement

• Deck joint replacement

• Deck and parapet replacement

• Deck, parapet, and girder replacement

• Deck drainage replacement

• Bearing replacement

• Entire superstructure replacement

Need to rehabilitate: The primary reasons are safety, continuity of use, and failure prevention The following considerations are of paramount importance:

• Correcting deficiencies

• Improving traffic conditions, geometry, sight distance, and clearances

• Increasing load-carrying capacity

• Providing for possible future widening

• Minimizing the costs to be incurred

• Addressing environmental concerns

Various types of failures, their causes, and methods of preventing failures need to be analyzed Repairs should directly follow the recommendations presented in inspection reports Emergency repairs are generally required immediately after an emergency or after extreme events, such as vessel collision, flood scour, or earthquake

Eligibility to rehabilitate: An experienced or licensed professional engineer is qualified to oversee the delicate tasks

Foundation failures: The following causes of failures need to be rectified For widened structures, differential settling of new and old components in widening shall be considered It is possible that the existing foundation has settled New footings may need to be placed on piling or drilled shafts in an attempt to prevent differential settlement The widened section should be designed so that superstruc-ture deflection for the new and old deck is identical

Scour analysis: Foundations need to be investigated for scour The investigation consists of ing on what the substructures are founded and the foundation depth as well as deciding whether potential scour will endanger the substructure’s integrity Local scour and stream meander need to be considered

There are notable differences in the construction steps between replacement and rehabilitation options when only the truck live loads govern