chapter 1 lecture1 kcs3233

8/13/2019 Chapter 1 Lecture1 Kcs3233

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TRANSPORTATION ENGINEERING

KCS 3233/KAS 4172

Prepared by : Madam Syarifah Anom Ibrahim



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CHAPTER 1 – Lec ture 1

CHARACTERISTICS OF THE

DRIVER, PEDESTRIAN,VEHICLE AND THE ROAD



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1.1 DRIVER CHARACTERISTICS

14% of driver population comprise of 65 years old andabove

However, the ability to hear and see decreasing after65years old.

Human response process is the action taken by thedrivers on a road, result from evaluation and reactionobtained from stimuli that they see or hear.

However, it must be carried out in a very short time.

Therefore, it is important to the highway & transportationengineer to have some fundamental knowledge of visualand hearing perception



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5 types of visual perception

1. Visual acuity

2. Peripheral vision

3. Colour vision

4. Glare and recovery

5. Depth perception



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1. Visual acuity

Visual acuity is the ability to see finedetails of an object.

Two types of visual acuity; static &

dynamic visual acuity.Factors that affect static acuity;

background brightness, contrast and time.

Most drivers have clear vision within the

conical angle 3-5 degrees, 10-12 degreesfairly clear, beyond this angle, usuallyblurred.



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2. Peripheral vision

Peripheral vision is the ability to see

objects beyond the cone of clearest vision.

Although objects can be seen within this

zone, but it not clear in details and colour.

Factors affected; speed of vehicle & age of

the driver



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3. Colour vision

The ability to differentiate one colour from

another.

Deficiency of this ability is considered

colour blindness



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4. Glare vision & Recovery

There are 2 types of glare vision; direct & speculars.

Direct glare vision – occurs when relatively bright lightappears in the individual’s field of vision

Speculars glare vision – when image reflected by therelatively bright light appear in the field of vision

Both conditions can cause discomfort to the eyes.

From dark-bright ; 3 seconds glare recovery

From bright-dark; > 6 seconds glare recovery

By age of 40, people are more sensitive to the glare.



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5. Depth perception

The ability of a person to estimate speed anddistance.

It is importance on 2-lane highways duringpassing maneuvers

This is due to the ability of human eye todifferentiate between objects

However, human eye is not very good to

estimate absolute speeds, distance, size andaccelerations.

That is why traffic control device are standardin size, shape and colour



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Perception – reaction process

1. Perception = the driver sees the control device, warning

sign or object on the road

2. Identification = the driver identifies the objects andunderstand the stimulus.

3. Emotion = the driver decide what action to take

4. Reaction = the driver executes the action decided during

the emotion sub-process



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According to AASHTOO, recommended time for the perception-

reaction time is 2.5 seconds.

JKR suggested 3 seconds

EXAMPLE 1:

A driver with perception reaction time of 2.5 sec is driving at 65km/h when

he observes that an accident has blocked the road ahead.

Determine the distance that the vehicle will move before the driver couldactivate the brakes. The vehicle will continue to move at 65km/h during the

perception reaction time of 2.5 sec.

SOLUTION:



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1.2 Vehicle characteristics

Geometric design criteria of the road is partly based on the

; static, dynamic & kinematics characteristics of the

vehicle.

Static; include weight & size of vehicle

Dynamic; forces that causes the motion of vehicle

Kinematics; motion of vehicle without considering the

forces



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Conversions

1m = 3.28 ft

1 ft = 0.3 meter

1 mile = 1609.3 meter

1 meter = 0.000621371 mile

1 pound/lb = 0.45kilogram

1 kilogram = 2.2 pound/lb



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1.2.1. Static Characteristics

The size the design vehicle for a highway is an important

factor the determination of design standards for physical

components of the highway

These include; lane width, shoulder width parking bays

and length of vertical curves.

Table 3.1 shows the limit of static characteristics



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Table 3.2 : Dimension of Design Vehicle



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1.2.2 Kinematics characteristics

• The important element among kinematics characteristicsis the acceleration capability of the vehicle.

• For a standing start to a speed of 25km/h, typical

maximum accelerations are; – For tractor-semi trailer truck = 0.9m/s²

– For large car = 4.5m/s²

For a speed change 0 to 48 km/hr, typical maximum accelerations

are;- For tractor-semi trailer truck = 0.5m/s²

– For large car = 3.1m/s²

– For high-performance sport car = 4.3m/s²



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1.2.3 Dynamic characteristic

• Several forces act on a vehicle while it in

motion;

1. Air resistance

2. Grade resistance

3. Rolling resistance

4. Curve resistance



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1. Air resistance (R a)

Ra = air resistance (kg)

p = air density (1.227kg/m³)

CD = aerodynamic drag coefficient; 0.4(car), 0.5-0.8(trucks),0.5 typical v A = front cross sectional area (m²)

u = vehicle speed (km/h)

g = gravity (9.81)

g

Au pC R D

a

277.0

5.0



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2.Grade resistance

• m= vehicle mass (kg.s²/m)

• w = vehicle weight (kg)

• g = gravity (9.81)

• ⍬ = incline angle (°)

• G = gradient (%)

sinmg RG 100

wG RG



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3. Rolling resistance (Rr )

• R = rolling resistance force (kg)

• Crs = constant (0.012 for passenger car)

• Crv = constant (7 x 10-6 s2/m2)

• u = vehicle speed (km/h)

• W = gross vehicle weight (kg)

W uC C R rvrsr

2077.0



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4. Curve resistance

• Rc = curve resistance (kg)

• u = vehicle speed (km/h)

• W = gross vehicle weight (kg)

• g = acceleration (9.81)• R = radius curvature (m)

gR

W u Rc

2077.0

5.0



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Power requirements

• P = horsepower delivered (hp)(1 hp = 0.75 kw)

• R = sum of resistance to motion (N)

• u = speed of vehicle (km/h)

• v = vehicle velocity (m/s)

Rv P 76

278.0 Ru P



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Example 2

Determine the horsepower produced by a passenger car traveling at a

speed of 105 km/h on a straight road of 5% grade with a smooth pavement.

Assume the weight of car is 1800kg and the cross-sectional area of the car

is 3.8m² (pg 77)



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1.3 Road characteristics

• The road characteristics is related to

stopping and passing sight distance

because more related to the sub topic as

discussed before.

• Sight distance

• Sight distance is a length of highway

visibility ahead to the driver of a vehicle.

There are 2 sight distance situation

considered in the design.



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1.3.1 Stopping sight distance

• SSD for design purpose, is usually taken as the minimum sight

distance required for the driver to stop the vehicle after seeing an

object in the vehicle’s path without hitting the object.

G g

au

ut SSD

254

278.02



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Example 3

• A temporary diversion has been constructed on a highway of +4%

gradient due to major repairs that are being undertaken on a bridge.

The maximum speed allowed on the diversion is 10mi/h(10km/h).

Determine the minimum stopping sight distance on the highway.

• Take a/g = 0.35

• Perception reaction time = 2.5s



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1.3.2 Passing sight distance

• The passing sight distance is the minimum

sight distance on a 2-lane, 2-way highway that

will permit a driver to complete a passing

maneuver without colliding with opposingvehicle & without cutting off the passed vehicle

4321 d d d d PSD



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chapter 1 lecture1 kcs3233

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