Thiết kế tổ chức thi công nền mặt đường

According to the highway specification TCVN 4054-2005 then: Design trafficvolume is number of the passenger cars converted from all the vehicles which isforecasted to pass a cross sectio

PREFACE

In the career of building and protecting country, Communication and Transport are essential contributing important roles Along with country's continuous development in the past years, field of capital construction generally and civil engineering construction in particular have invested by Government and Party and having deservedly proud achievements In the next years, in order to implement the career of modernization and industrialization, Communication and Transport must precede a step, serve purposes of socio-economic development.

In the recent years, the government is investing much in Transportation and Communication; advanced constructing technologies are applied in Vietnam To apply in fact, civil engineers’ level must be better and better To satisfy demands of development, The University Transport and Communication is opening scope and raising quality of training.

After learning and gathering knowledge in the University Transports and Communications, now I am designing a graduation thesis about the road and highway I am guided directly by Doctor Do Quoc Cuong and other lectures in the Road and Highway section, Civil engineering department of the Hanoi university of transports and

communications I thank the lectures of the subject, especially , my guide lecturer Doctor

Do Quoc Cuong, my revise lecturer.

I have tried to do my thesis best with my knowledge, but it is not very good because

of time and some other reasons I hope advices, remarks and suggestions of teachers and all

of you.

Thank to you sincerely!

Ha Noi, May-2012 Student

Nguyen Anh Dung

THE REMARK OF GUIDE LECTURER

……….

Dr Do Quoc Cuong

THE REMARK OF REVISE LECTURER

……….

Dr Do Vuong Vinh

PART I PRELIMINARY DESIGN

CONSTRUCTION INVESTMENT PROJECT

HIGHWAY ROUTE A - B CONTRUCTION PROJECT OPTIONSTATION : KM0+00 TO KM6+875

BUON TRI AS DISTRICT, DAK LAK PROVINCE

CHAPTER 1 INTRODUCTION

1.1 BACKGROUND OF THE PROJECT

Project name: Highway investment project

Location: Alignment A-B is located in Buon tri As district, Dak Lak province.Project manager: Ministry of transport

Consultant organization: The University of Transports and Communications Designer: Nguyen Anh Dung

English Roads and Bridges Class 48th

University of Transports and Communications

1.2 OUT LINE OF THE PROJECT

1.2.1Objectives of the Project

The main objectives of the Project implementation can be summarized asfollows:

The new road is strategically located at Dak Lak province to contribute to theeconomic and social development of the Central Highland region in Vietnam

Concerns and improvement for the traffic safety, job opportunity and livinglevel of the local residents in the project area is an important factor in the sense toshare the profits of project

1.2.2 The base to carry out the project

Base on Dak Lak Highway investment and construction policy

Base on traffic volume investigation and forecast data

The annual vehicles’ development coefficient is 5% The design traffic volumeis: 3733 (vehicle/day)

in each part of Rear Axle

Distance

of the Rear axle (m)

Traffic volume ni (veh/day) Front Rear

Table 1-1: Forecast traffic volume

1.3 DOCUMENTS USED FOR DESIGNING

Survey

TCXDVN309-2004

G27 Procedure for static penetration testing (CPT and

CPTU)

22TCN320-2004

Road Design

collector road)

22TCN210-92

Pavement

P38 Flexible pavement design (to collate with standard

22TCN211-93)

22TCN274-01

No Name of Standards Standard Ref No

specification and testing method

22TCN279-01

polymer bitumen material

22TCN319-04

Water Treatment

CHAPTER 2 PROJECT AREA IN DAK LAK PROVINCE

2.1 INTRODUCTION AND GEOGRAPHICAL CONDITIONS

Area: 13.085 km²

Population: 1.759.136

Provincial capital: Buon Ma Thuat City

Economic potentialities: mineral, forestry, and tourism

The highland tropical monsoon climate which brings annual averagetemperature of 23-24 deg A is distributed into two separate seasons: rainy seasonfrom May to October, and dry season from November to April

Dak Lak is located at Central Highland, having the main roads connecting withmany cities and provinces, such as: National Highway number 14 linking Da Nang -Gia Lai, Ban Me Thuot, and Dak Nong, Binh Phuoc , Binh Duong and Ho Chi MinhCity, National Highway number 26 connecting Buon Ma Thuot with Nha Trang Cityand some other routes connecting the North East region with Cambodia

Some ethnic groups live in this area, including the Kinh, E de, and M’Nong.Famous sites include many water-falls like: Krong Kmar, Dray Sap, Dray Nu, ThuyTien, and a view of the Lak lake.

2.2 GEOGRAPHICAL CONDITIONS

Dak Lak is a large province of Central Vietnam It has borders with Gia Laiprovince in the north, Lam Dong province in the south, Phu Yen province in the east.And it also border Cambodia in the west, with the boundary of 193km in length

Dak Lak is comprised of three categories of mountain, plain and highlandterrains Being the dwelling place of many long-standing ethnic minorities, Dak Lak

is proud of the Cong Chieng culture

The greatest part of Dak Lak is located at northeast side of the Truong Sonmountain The highland terrain is at the middle of Dak Lak The remained part of thisprovince includes plains at south and north of Buon Ma Thuat city Dak Lak linkswith Hanoi and Ho Chi Minh cities by road and railway Dak Lak has a great area ofbasalt soil which is adequate to plant long-term industrial crops like: rubber, pepper,coffee, and fruiters

The project is located in Dak Lak province so that the Project Area has gotgeotechnical characteristics of Dak Lak province

2.3 TOPOGRAPHICAL CHARACTERISTICS

Topography of the project area is relatively asperity However, there are someplains in the project area The elevation of this area ranges from 400m to 530m.Basing on the results of topographical surveys, test drilling, field testing andlaboratory tests on the collected samples, the stratification of the area was dividedinto layer as following:

Organic soil was found on the ground surface The thickness of this layerranges from 0.2m to 0.3m

Eluvial clay soil: this layer distributes along alignment The thickness of thislayer ranges from 3m to 6m

Weathered rock: the color of this layer is yellowish brown, reddish brown.The thickness ranges from 4m to 6m

Bed rock: the most popular bed rock in this area is basalt rock

2.4 CLIMATIC CONDITIONS

The climate in the project area is under highland tropical monsoon climate.There are two distinct seasons: rainy season from May to October, and dry seasonfrom November to April of the following year

The monthly climatic records at Dak Lak are summarized in the figures givenbelow

The average annual rainfall is 2000mm at Dak Lak

Average temperature is 23-24 deg C over the year

Relative humidity is high throughout the year with an average of 81%

Average wind speed varies from 14m/s to 32m/s

Annual average sunshine hours is about 1600 hours in which, during the rainyseason, sunshine duration is the least and about 50-100 hours per month The mostsunshine duration is from May to July, exceeding over 280 hours per month

-evaporation -rain fall

1200

500

Table 2.1: Number of monthly rain day in Dak Lak

Source: Viet Nam Climate, by Mr Pham Ngoc Toan & Mr Phan Tat Dac, Technical and Science Publisher – 1993) TN: Dak Lak Meteorology Station (Temperature:

1950-1970, Rainfall: 1915-1925; 1930-1945; 1955-1970, Humidity: 1958-1970, Wind: 1959-1970, Sunshine: 1958-1970)

Figure 2.2: Wind flower in Dak Lak

Figure 2.4: Diagram of monthly evaporation in Dak Lak

It locates Buon Tri As district Topography of the section is generally downy,mainly forest Therefore hydrological regime depends on local rainfall and theirrigation works

In research region have only stream system, ditch system

2.6 CONSTRUCTION MATERIALS.

This section is prepared to provide followings:

 To determine the possibility of supply for required magnitude in the project;

The Project goes through the area where constructional material sources arepopular and advantageous The exploitation, supply and transportation conditions arevery convenient

Soil: sandy clay volume is quite large Sandy clay has high strength.Employment, transportation is convenient So, it is used for embankment very well

Stone: The quality of stone is quite good and satisfies Resistance strength israther high There are some quarries with large volume Sand: the quantities are large.The exploitation, supply and transportation are quite convenient

Water: is sufficient for construction

- Other environmental aspects

2.8 TRAFFIC CONDITIONS OF THE REGION.

(7.96%), province road is 460 km (9.2%), district road and commune road is 4000km(82%)

CHAPTER 3

DETERMINE THE TECHNOLOGY FACTORS OF ALIGNMENT

3.1 DETERMINE ROAD LEVEL.

3.1.1 DESIGN TRAFFIC VOLUME.

According to the highway specification TCVN 4054-2005 then: Design trafficvolume is number of the passenger cars converted from all the vehicles which isforecasted to pass a cross section of the road during the time unit in the computingyear ( the 20th year in this project)

3.1.2 ROAD LEVEL.

Design traffic volume is number of the passenger cars converted from all thevehicles which is forecasted to pass a cross section of the road during the time unit inthe computing year

Formula: Nde = ∑ (a N i i)

With: Nde : Design traffic volume (Veh/day)

Ni : Volume of vehicle type i in future year

Ni = Nipx(1+q)t

Nip: Volume of vehicle type at the presentq: Traffic growth =5%

t: Calculated time =15 (years)

ai: Equivalence factor from vehicle type i to passenger car

(veh/day)The current year

Traffic Volume(veh/day)The Forcast year

Equivalencefactor

Equivalence(veh/day)volume

Table 3-1: Volume of types of vehicle

So the total number of equivalence car is:3733 veh/day

the Viet Nam standard TCVN 4054-2005, the road level is level III

- Base on the importance of the road is connecting economic and politic centers

of the province

- Base on the future development plan of the province related to transport andcommunication’s developments

So, the road level is chosen is: level III

Design Speed chosen is 60 km/h

3.2 CAPACITY OF THE ROAD.

The capacity of the road, (N) is maximum number of vehicle that can be able topass continuously through any cross section during time unit

N = vehicle per day (VPD) or vehicle per hour (VPH)

3.2.1 IDEAL CAPACITY OF THE ROAD.

The ideal capacity of the road, Nlt is the capacity which is determined in idealcondition (including the road condition and vehicle condition)

+ Assumption: vehicle continuously move on the road, the same kind of vehicle

which is required so sufficient that if any vehicle suddenly stop then the driver of thefollowed on keep in time to perceive and put on the brake to stop safety Lo is calledkinetic size of vehicle

+ Schema, refer to figure 3-1

+ Calculation

Formula:

NLT =

o L

i = 0

v v

- Lo : kinetic size of vehicle (m).

v(km/h)

lpu =

- lx : vehicle length lx = 6 m

- lo : safe distance lo= 5 m

- Sh : braking distance, is calculated:

) ( 254

1000

2 2

i

V K

V S

lt

l l i

V K V

V N

+ +

±

× +

=

) ( 254 6 3

- i :gradient of the road, in normal condition i = 0

- ϕ : longitudinal coefficien of friction, in favourable concision ϕ = 0.7

3.2.2 ACTUAL CAPACITY OF THE ROAD.

The actual capacity of the road, Ntt is the capacity which is determined in theactual condition of the road and traffic

+ The actual capacity (Ntt)

The actual capacity is equal to (0.3 0.5 ÷ )N lt

So: Ntt = (0.3 0.5 ÷ ) N lt= 346÷578 (veh/h)

Base on normal condition of the road, we have: Ntt = 0,4Nlt = 462 (veh/h)

3.3 SPECIFIC GEOMETRY OF CROSS SECTION.

3.3.1 GENERAL INTRODUCTION.

Cross section is significant component for describing the road shape which ischanged depending on the terrain condition

Pavement consist of carriageway and shoulder and median (if need)

When design speed is larger or equal to 60 km/h, shoulder must be treated

In the project, median is not located and shoulder is treated

3.3.2 DETERMINE THE NUMBER OF LANE.

Determine the number of lane is to specify the carriageway fited traffic demand(road capacity satisfies the traffic volume)

According to the specification TCVN 4054-2005 we have:

The number of lane is determined by the formula:

nl =

cl

ph

N z

Ncl : the capacity of the lane

Z: traffic serving rate (degree of using capacity) Z = (0.55-0.77)

According to TCVN 4054-2005, with the 60km/h design speed we haveZ=0,77

Carriageway width is determined basing on the number of lane, lane width,distance of two vehicles in the opposite direction.

Figure 3-2 Determine the lane width

- a: body width

- c: Distance between two wheels

- x : Distance from edge of the body to the median

- y: Distance from the wheel to edge of part that the truck runs on

- l2: lane width, l2=(a+c)/2+x+y

y = 0.5 + 0,005V (m) with driving contrariwise

l2=(a+c)/2+ 1 + 0,01V

With design speed, V =60(Km/h) ⇒ l2 =0,5x(a+c) + 1,6 (m)

a Calculating for truck.

a

According to standard TCVN 4054-2005 we have main parameters of cross section:

+ Road bed width : B = 9 (m)

Shoulder is the surfaced strip of roadway immediate adjacent to the carriageway edge

The faction of shoulder:

+ As a widening part of pavement to increase the safety and reliability forvehicle operation

+ For emergency stopping

+ Temporary extra traffic lanes during road maintenance or carriagewayreconstruction

+ For increasing the sight capacity on the road

+ As a structural support to the pavement

+ As a manner for increasing LOS (level of service) and capacity of the road

Shoulder structure:

Shoulder consists of treated strip and untreated strip Untreated strip is edge strip

of roadway which is rounded or unrounded and usually grassed (0.5-1m) Treatedshoulder (hard strip) should be flush and the same construction with carriageway to

be able to support vehicles under all weather condition, so that there are no skidding

or rutting problems when driving on their surfaces Treated shoulders also serve alltypes of non-motorized vehicle

According to Viet Nam standard TCVN 4054-2005, with road level is level III

and design speed is 60 km/h, shoulder width is 1,5 (m) and treated shoulder width is 1(m)

3.3.5 CROSS SLOPE (CROSS FALL).

In order to drain surface water from the pavement and avoid pounding in surfacedeformations they create a cross slope for central strip or they make the convexity ofpavement and it is termed “camber”

Depending on the type of pavement surface and the treated shoulder part isusually the same construction with carriageway In order to satisfy favorableexecution, cross slope of treated shoulder is the same slope with pavement

According to TCVN 4054-2005, we choose:

+ Cross slope of carriageway: 2%

+ Cross slope of treated shoulder: 2%

+ Cross slope of soil shoulder: 4%

3.4 DETERMINE SIGHT DISTANCE.

Sight distance is minimum visible distance in front of the driver It is veryimportant to calculate and provide the driver with the sign distance so sufficient that

he can treat safety any case which suddenly happens when car moving on the road.Sight distance calculations, the height of the driver’s eye and height of the objectare considered to be 1.0 (for the same direction) or 1.2m (for opposite direction) and0.1 m above the road surface respectively

3.4.1 STOPPING SIGHT DISTANCE (SSD).

the driver sight a obstructive object in his path the just in time to put on the brake tostop the vehicle at point which is far from the object a safe distance lo

Computing sight distance:

Figure 3-3: Determine stopping sight distance

According to this scheme: S1 = Lpr + Sh + L0

Computing sight distance depend on V(Km/h), we have:

S1 =

6 3

V

(m)

- Sh : Braking distance: Sh =

) ( 254

- k : coefficient of the brake using, k = 1,2 for passenger car

- ϕ : Longitudinal coefficient of friction: ϕ = 0.5

- i : Gradient of road, for unfavourable condition, we choose: i =7%

) 07 0 5 0 ( 254

2 60 2 1 6

3

⇒ So we choose the stopping sight distance is: S1 =75 m

3.4.2 OPPOSING SIGHT DISTANCE (OSD).

on the single lane or narrow two lanes, the driver discovers an oncoming vehicle andjust in time to stop the vehicle safely

Computing sight distance:

Figure 3-4: Determine opposing sight distance

Computing sight distance follows: V(Km/h):

60

2 2

3.4.3 AVOIDING SIGHT DISTANCE (ASD).

Avoiding sight distance S3 needs to be computed so sufficient that vehicle 1 ismoving on the path of vehicle 2, detects the vehicle 2 and keep in time to turn to itslane for avoiding safely

Calculating sight distance:

Figure 3-5: Determine avoiding sight distance

Avoiding sight distance is calculated by formula:

=> 4 3 101.2 5 102.54( )

8.1

Figure 3-6: Determine passing sight distance

3.5 DETERMINE MAXIMUM GRADES OF THE ROAD.

3.5.1 DETERMINE MAXIMUM GRADES BASE ON DYNAMIC FACTOR.

Calcultion principle: Pulling force of vehicle must be larger than summary ofimpediment force Maximum grade is calculated depending on the capacity of vehicletype that can be overtaking slope of the road Otherwise, maximum grade iscalculated depending on dynamic factor By formula:

- f : rolling impediment coefficient: f = 0,02 (asphalt concrete pavement)

- i : grade of the road ( %)

- j : relative acceleration of vehicle j =

dtdv

- δ : coefficient considering the rotation of the machine (δ=1.03-1.07)

- g : gravity acceleration, g = 9.81 m/s2

( (+) when go up, (-) when go down)

Assumption: the vehicle have uniform motion, we have: j = 0

To compute in unfavorable condition: when vehicle goes up the slope

Dk/ f + i ⇒ idmax= Dk – f = Dk– 0.02

vehicles and (in Road design book) and substitute them to above formula, take thetable:

vehicles

Table 3-2: Dynamic factor and maximum grades

Because cars are outnumbered others vehicles, we use car for design vehicle, sobase on this table, the idmax = 7 %

3.5.2 DETERMINE MAXIMUM GRADES BASE ON CLINGING FORCE.

According to the condition of clinging force between the types and carriageway,

in order to vehicles move safety, the clinging force between the types andcarriageway must larger than the pulling force of vehicle So maximum grades of theroad must smaller than grades that is calculated basing on the clinging force (ib) ibiscomputed in case the pulling force of vehicle equal to the clinging force between thetypes and carriageway

Assumption: the vehicles have uniform motion, we have: j = 0

To compute in unfavorable condition: when vehicle goes up the slope

- ib : Grade of the road (base on clinging force)

- G : Whole vehicle load

- Gb : The load in positive wheel:

+ Truck: Gb = ( 0.65÷ 0.7 ).G+ Passenger car: Gb = ( 0.50÷ 0.55 ).G

- ϕ : longitudinal coefficient of friction In the most unfavorable case: ϕ = 0.3

- Pw: Air impediment force

13

.F V2

K

Where:

- K: air impedient coefficient, depending on air density and vehicle shape

- F : Area of the maximum cross section of vehicle which is perpendicular tomoving direction (air impediment area, m2)

F = 0.8BH

Where: B: Vehicle width

Table 3-3: Grades of the road depending on clinging force

condition checked in this table is good

According to Viet Nam standard TCVN 4054-2005, with design speed is 60km/h: we choose grade of the road: 7%

Combine calculation and standard, we propose to choose grade of the road is7% in order to design AB alignment

3.6 DETERMINE MINIMUM RADIUS OF HORIZONTAL CURVE.

The aim of designer is to determine the component of road to fit the demand ofserving through, safely, smoothly, economically and aesthetically the traffic That iswhy, in principle the radius of curve should be as great as possible However, inmany situations, depending on the terrain condition it is needed to use sharp curve toavoid a too great earthwork or disadvantage condition… In that case, in order to besafe for vehicle moving on outside lane of curve, the pavement should be designedthe same cross-fall inclining to the center of curve (superelevation)

3.6.1 MINIMUM RADIUS OF CURVE WITH SUPERELEVATION.

In disadvantage case, minimum radius of horizontal curve is calculated withsuperelevation 8%

Rmin =

)i127(

V: Design speed, V = 60 km/h

µ : Lateral force coefficient, normally: µ = 0.15

iscmax : superelevation, iscmax = 7%

+ 0 07 ) 15

0 ( 127

60 2

128.8 mAccording to TCVN 4054-2005, minimum radius of curve with superelevation7% is 125 m We propose: Rscmin = 125 m

3.6.2 MINIMUM RADIUS OF NORMAL CURVE.

Normal curve is the curve in which all cross section is normal cross section(without superelevation) Minimum radius of non-superelevation curve is symbolized

RminKSC And RminKSC is calculated by formula:

Rmin =

) i μ 127(

0 ( 127

60 2

472(m)According to TCVN 4054-2005, minimum radius of normal curve 1500 m So,

we propose: RminKSC = 1500 m

3.6.3 RADIUS OF CURVE WITH NORMAL SUPERELEVATION.

In normal case, radius of horizontal curve is calculated with superelevation 4%

0 ( 127

60 2

149 m

According to TCVN 4054-2005, minimum radius of curve with superelevation4% is 250 m So, we propose: Rscmin = 250 m.

3.7 WIDENING IN CURVE.

While the vehicle moving in the curve, each tyre move in a different path: theconstant rear axis always lead to the radial while the front axis and rear axis make anangle, so the vehicle need a bigger widening in curves Therefore, to make themoving of vehicle as comfortable as moving in the straight line, the small-radiuscurves (<250 according to TCVN 4054-05) need to have widening The number ofthat widening have to make sure the distance between the car and the shoulder,between two cars just like in the straight line

Figure calculating widening in the curve

Refer to Figure, we have: Eg = e1 + e2 ≈ 2e2 = L2/R

Geometric widening is widening in static situation In fact, it needs to beconsidered in the condition of vehicle moving In that case, due to the influence of

8 2

L: Length from axle’s vehicle to axle of the next one, L=8 m

According to TCVN 4054-05 the widening in the curve with Vtk = 60 Km/h, Rmin =250(m) is 0,6 m

So we choose the widening in the curve is 0,6(m)

3.8 DETERMINE SUPERELEVATION AND SUPERELEVATION TRANSITION.

3.8.1 SUPERELEVATION.

In sharp horizontal curve, in order to increase the lateral resistance (decreaseeffect of centrifugal force), stability of vehicle moving on the outside lane, thesurface of pavement is designed to incline to inside direction of curve That is termed

R : Minimun radius of horizontal curve with superelivation

µ : Lateral force coefficient (µ = 0.15: ratherly perceive the curve)

V : Design speed V= 60 km/h

Substitute for calculation formula, we have:

077 0

60

According to TCVN-4054-2005, maximum rate of superelevation is 7%

Combine between calculation and standard to choose maximum rate ofsuperelevation: 7%

The transition distance from normal crown on the tangent to full superelevation

is designed to make crossfall changing gradually and smoothly It is symbolized Lsc.The process of establishing Lsc makes the grade of outsite edge of pavementincreasing a value which is equal to ip (supplemental grade)

Transition distance is calculated:

i p : supplemental grade, with Vtt = 60 km/h => i p = 1%

Depend on every curves, we have different Lsc

Figure 3-7: Super-elevation

3.9 SPIRAL CURVE.

When moving from the tangent to the horizontal curve, the vehicle is impacted

by the changes such as:

+ Radius of orbit reduces from ∞ in tangent to R at the curve

+ Centrifugal acceleration (a) increases from 0 up to a = V2/R

+ Centrifugal force also increases from 0 up to

2

GV C gR

=

+ Deflection angle α(of front axle and central line of vehicle) increases from

0 in the tangent up to α=αo= lo/R at the curve.

The purpose of the spiral curve is to provide a smooth and safe transitionbetween tangent and circular curve Thus, the spiral curve must be designed to haveshape which is suitable with vehicle orbit so that centifugal acceleration is graduallychanged

The length of spiral curve must be larger than superelevation transition distance,widening transition distance

The length of spiral curve is computed:

Lsp =

R

V

5 23

3

Where:

+ V: design speed, V = 60 km/h

+ R: radius of curve

With different radius of the curve, we have different value of Lsp

According to TCVN 4054-2005, with road level: 60 km/h, minimum length ofspiral curve is 50 m

And according to TCVN 4054-2005:

+ When design speed is larger than or equal to 60 Km/h then spiral curve must

be established

+ For transition curve, spiral curve may be subsituted by the curved:

- The combination circular curves.

3.10 ENSURE SIGHT DISTANCE IN HORIZONTAL CURVES.

S

O

Figure 3-8: Sight distance in curves

When vehicle move on inside lane in the curve The sign of driver may beeclipsed by obstructions such as: house, trees, high cut slope … Thus, we have toconsider the sight design in the curve

+ AB: sight line of driver, AB = S = calculating sight distance

+ Z: maximum distance from the orbit of vehicle moving on inside lane to AB.+ Zo: distance from the orbit of vehicle on inside lane to edge of obstruction.If: Z Z≤ o then the sight of driver is adequate

Z > Zo then the sight of driver is inadequate and have to design for clearance

at the inside of the curve (determine Z)

+ Orbit of vehicle in inside lane is perceived: 1.5 m far from inside edge ofcarriageway

+ Driver’s eye elevation is about 1÷1.2 m

According to analysis method, there are two cases in order to determine sightdistance in the curve:

+ Sight distance S is not larger than the length of curve K:

) 2 cos 1 ( − α 1

=R Z

+ Sight distance is larger than the length of curve:

2 K)sin (S

2

1 ) 2 cos R(1

Where: ;: deflection angle

;1=180o.S/πR

R: radius of the curve

3.11 ENSURE SIGHT DISTANCE IN PROFILE.

3.11.1 ENSURE SIGHT DISTANCE.

To ensure sight distance in profile, we only consider to crest curve, because sagcurve is satisfied Basing on sight distance in oder to determine radius of crest curverespectively

Figure 3-9: Sight distance in vertical direction

To ensure two directions of sight distance: rmin =

ω4d

rmin≥ S1 then sight distance is satisfied

rmin< S1 then sight distance is not satisfied

2 1

4 ×

= 240 > S1 =75(m)

⇒ Sight distance is satisfied

In the case: rmin = S1 = 75 (m)

4×

= 0,064 = 6.4/0

So, with ω> 6.40/0 then consider sight distance in the vertical curve

3.11.2 MINIMUM RADIUS OF VERTICAL CURVE.

The vertical curve is established to make smooth, safe transition and provide a

sufficient sight for vehicle moving between the adjacent grades At changed directionposition which algebraic difference between two rate of grades is larger than or equal

to 1% (for V ≥ 60Km h/ ) or 2% (for V<60 Km/h), must be designed the vertical curve.The vertical curve is circular curve or parabola curve

3.11.2.1 Minimum radius of crest curve.

Minimum radius of crest curve is determined by the requirements of sightdistance.Crest curve is circular curve and Rmin corresponding to the driver’s sight isequal to sight distance (s)

Figure 3-10: Minimum radius of crest curve.

d1: driver’s eye heigh

2

) d d 2(

S R

+

=

- With sight distance is opposing sight distance, d1 = d2 = d (driver’s eye height)then:

S R

To propose using minimum radius = 2500 m in order to design crest curve

3.11.2.2 Minimum radius of sag curve.

+ According to centrifugal force condition:

When vehicle move on the sag curve, it is compacted by gravity and centrifugalforce Centrifugal itself may cause to overload for vehicle bearing So, it is important

to control the value of centrifugal force (C)

Centrifugal acceleration is determined:

b R

V a

V R

606.5

According to TCVN–4054-2005, limited minimum radius of sag curve withdesign speed 60 km/h is 1000 m and normal minimum radius of sag curve is 1500 m

To propose using minimum radius = 1000 m in order to design sag curve

3.11 CLEARANCE

3.12 TOTAL GEOMETRIC FACTOR OF THE ROAD.

From technology factor calculation of alignment and combine with Vietnamstandard Basing on actual condition of the road, technology, economy, we propose touse basic technology factors of alignment that as follows:

No Technology factor unit Value Proposal

CHAPTER 4 ALTERNATIVE ROUTES ON THE PLAN

4.1 OVERALL DESIGN.

4.1.1 SELECTION OF ALIGNMENT.

Selection of main alignment direction must be based on given alignmentdirection (the end points and limited points), class of road and its function in roadnetwork,in addition to combine factors such as : waterway, railway, airway, pilelineand state of cities, hometowns, industrial zones, capital; and combination to natural,hydro-meteorological, geological, topographical conditions as well so that from thesevalue, through analysis and comparision we can choose the most suitable alignment

4.1.2 MAIN FACTORS IN OVERALL DESIGN.

After determining horizontal alignment direction and class of road, we mustarraign alignment in integrity Some principle problems must be carried out:

+ Depending on traffic volume, characters of terrain to determine terrain type,road class and design speed

+ Besides the end points demand must be suitable with planning road network,designers have to present alternatives of alignment joint so that in the future thealignment can be stretched

+ Determining number of lane bases on traffict volume and vehicle movementdemands

+ Estimate road length, select transition points between sections suitablely Solvealignment shape of sections at joint positions the best

+ Survey plane of cities, hometowns along the road, decide alternative andposition of jointing them

+ Survey natural, traffic and social conditions along road, determine intersectionpositions

+ Basing on function of road, decide safe measurments, manage traffic, positionand arrangement of bus stops, garage services