transportation eng 2 (notes).pptx repaired]

8/3/2019 Transportation Eng 2 (Notes).Pptx Repaired]

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REPUBLIC OF RWANDA

MINISTRY OF EDUCATION

KIST

FoE - CE&ET DEPARTMENT

By : EDWARD KYAZZE (PLANNING ENGINEER)

Visiting Lecturer

TRANSPORTATION

ENGINEERING II


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MODULE MAIN CONTENT

yUnit 1- Introduction

yUnit 2- Traffic Engineering

yUnit 3- Hill Roads

yUnit 4- Highway Economics and

Finance


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DETAILE

DOUTLINE

oUNIT 1- INTRODUCTION

- Functions of Traffic Engineering

- PIEV Time Theory and Impacts


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DETAILED OUTLINE

oUNIT 2- TRAFFIC ENGINEERING- Traffic Flow Parameters

- Traffic Characteristics

- Pedestrian and Bicycle Concepts- Estimation of Design Traffic

- Design and Evaluation of Signalized &

Un-signalized intersection- Parking Design

- Highway Lighting

- Simulation Model !!


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DETAILED OUTLINE

oUNIT 3- HILL ROADS

- Geometric Design and Alignment

- Drainage Design

- Maintenance Problems


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DETAILED OUTLINE

oUNIT 4- HIGHWAY ECONOMICS

AND FINANCE

- Highway costs

- Highway user benefits

- Economic Analysis

- Highway Financing


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Indicative Content (In given

time frame)y Traffic Engineering: Traffic Characteristics, Traffic

Operation, Definitions and Measurements of TrafficVolumes, Speed and Density; Analysis of Spot Speeds,Moving Car Observer Experiment, Estimation ofDesign Traffic, Speed-Volume-Density Relationships,Design and Evaluation of Signalised and Non-signalised Intersection, Design of Parking Facilities,Highway Lighting

y Hill Roads: General Considerations, Alignmentand Geometrics of Hill Roads, Drainage of HillRoads, Maintenance Problems in Hill Roads

y Highway Economics and Finance: Highway Costsand Highway User Benefits


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REFERENCESy Wright H.P & Ashford N.J (2007), Transportation

Engineering, Planning and Design 4th Ed., JWand sons

y Macpherson Gavin (1993): Highway and Transportation

Engineering and Planning, Longman UKy Salter J.R (1990):Highway Design and Construction 2nd

Ed., Macmillan

y Salter J.R (1984): Highway Traffic Analysis and Design

y Morlok K.E (1998): Introduction to TransportationEngineering and Planning

yAdd other soft copies


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ARRANGEMENTSo Lectures : Saturday ( 8:00-16:00)

(With Myself & Other Visiting

Professional Field Experts)

o

Practicals & : To be planned & communicatedTutorials

oNotes : Lectures and guideline docs

(soft and Hard copies)

oAssessment : Practicals; Assignment (2)

Test (1); Exam


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INTRODUCTIONoWhat is traffic traffic engineering?

oWhat are the functions of traffic

engineering?- Categories traffic flow:

oHow do we analyze traffic facilities?


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FUCTIONS OF TRAFFIC ENGINEERING

Planning and travel forecast.y Involves the planning , functional design

,operation and management of transportationfacilities.

Collection of factual information .

y Done through traffic studies e.g traffic volumes,speed and delay studies parking studies ,accident

studies etc.Design and placement of control and regulationmeasure

y Traffic design signals , marking , speed control ,

parking prohibitions.


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FUNCTIONS OF TRAFFIC ENGINEERING

Research

yDevelop more efficient ways and techniquesfor operating and managing transportationfacilities.

Traffic accident recording and analysis.yRecording and analysis causes of accidents

and suggest counter measures.


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ELEMENTS OF TRAFFIC ENGINEERINGy Traffic engineers(ing) deal(s) with:

- people

- vehicles- highway (road) network and

- environment by people

Here we mean mainly drivers, pedestrians, motor andpedal cyclists as well passengers.


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DRIVER CHARACTERISTICS

yPIEV time theory(reaction time) = definitiontime taken for a driver to initiate an action as result ofan external stimulus.

y P = Perception - Is the initial perception of thestimulus which may be visual, auditory, tactile orcombination of the above. (Action of seeing

something on the road)y I = Intellection - Is the process of understanding the

stimulus (Action to know what it is,e.g: a paperflying in air, people crossing, levying, )


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PIEV Time Theory Contdy E = Evaluation - Making mental decision regarding

possible responses

(Action of thinking about option one isgoing to take)

yV = Volution - Is the initiation of physical action(Initiating the chosen option)


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Note:y PIEV time is a random quality which varies from a

person to another for identical stimulus.

y

Furthermore it depends on the situation such asdrivers condition (fatigue, emotion, disability, drugs)or ambient conditions etc.

y Studies have shown PIEVtime ranging from 0.3 to 2.0seconds on a mean of 0.75 sec.


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EVALUATION PROCESS (Example)

y Consider for example the driver of a vehicleapproaching an intersection while the signalindication is turning to yellow (amber) the driver

has several options : stopping , continuing at thesame speed , or accelerating.

y The driver here is operating under condition ofuncertainty regarding the possibility of accidentor being cited by police or the amount delay if hestop.


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THE PIEV IMPACTS


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VISION1. Cone of vision

y Most drivers have accurate cone of vision of 30 to 50and an adequate cone of vision of 100-120 in whichimages are clear.

y Traffic signs should be placed at a cone of vision notmore than 120


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VISION2. Glare look at with fixed eyes vision &

recovery

- An eye takes time to adjustwe go from light to dark ordark to light.

y Glare recovery time is the time taken to recover fromthe effect of glare .

y Importance : the lighting arrangement at highlylighted areas as tunnel entrances and exits must takeinto account human behavior.


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VISION3. Color vision and color blindnessy In general human eye is sensitive to black & white as

well as black & yellow combination . Optimum colors

scheme for making and signs should consider thishuman behavior . Color blindness is an inability todifferentiate green and red .

yAbout 9% of males and 4% females in north America

are color blind. In Africa, its lesser than that.y Bluish green is used in green traffic signals to address

it.


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PHYSICAL, MENTAL & EMOTIONAL

FACTORSy Intelligence : it is found that persons with

super intelligence are not mentally attentiveto the task of driving.

yEmotions : fear , anger ,worry and otheremotional states lend to create disorganizedreaction.

yMotivation : on one hand safety & comfort,saving time on the other hand.

yLearning: Repetition, Trial and Error &

From previous experience.


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THE DRIVING TASKy Tracking

y Object avoidance

Three points considered here:yA = Action Point (the point at which stimulus

commences);

y M= Mental Point (the point at which we think to apply

break before reaching the object) andy T=True Point (the minimum point beyond which the

action may fail/ not succeed)

y Refer to cases in figures


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APPROCHES USED IN PROVIDING

TR

ANSP

OR

TATION FACILITIES .

y The facility is designed as per defined humanbehavior

y The human behavior is adjusted as per fixed facilitythrough control and regulations.


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VEHICLE CHARACTERISTICS

1. Vehicle lengthy Designing of parking facilities , temporary vehicle

storage lays such left/right turn lanes. Alsominimum turning radius extra widening of curves, passing sight distance etc.

2. Vehicle width.

y Lane width , width of the shoulders , parking

facilities etc.3. Height of the vehicle :

y clearances provided over a bridge, subways ,electricservice lines , traffic lights.


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VEHICLE CHARACTERISTICS4. Speed of the vehicles.

y Horizontal and vertical alignments, super elevationdesign of interersection.

5. Power of the vehiclesy Braking distances.

6. Acceleration characteristics.

y

Overtaking operations7. Braking characteristics

y Braking distances

8. Head lights of vehicles

y Night operations (vertical curves)


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VEHICLE KINEMATICS

AccelerationAcceleration : a= v v0 /t

yV = v0 +at

yX =v0 +1/2 at2

yX =v2 v02/2a

yAcceleration : a= v v0 /t

y

Having :. v0=50 km/hr V = 80km/hr ; 3sec = t

What is a?

yA = 2.8m/sec2 =uniform acceleration.


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yNON UNIFORM ACCELERATIONTHEORY

y dv /dt=-v

y In reality acceleration is not uniform , it varies inverselywith speed and can be given by the expression:

* .. i) (acceleration )

y *v0vdv / v = 0t dt .. (velocity).

yV= / (1- e t )+ v0e-t

yX = t/ /2 (1- e-t ) + v0 / (1- e-t)

yThis will be discovered at length (in

tutorials) during the course


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y VEHICLE DYNAMICS

*The force that takes up the car isattractive force delivered by the engine.

y *Forces opposing traction

i) Friction force (rolling resistance)

y depend on the type of road surface, frictionbetween tyres and road surface.

y ii) Air resistance depends on the speed, frontarea of vehicle and direction & velocity of thevoid.

yThis will be covered at length in tutorials


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Frictional

force

weight Graderesistence


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(iii)Grade resistance

y Effect of gravity which depends on the slope andthe weight of the vehicle:

y

Gr=WsinU


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BRAKING DISTANCE

Vehicle traveling uphillInitial speed = V1

Final speed = V2

S = skidding distance after applying brakes.The distance, S, traveled while skidding from V1 to

V2


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On a slope of angle U is given by:S = (V12 V22)/[2gcosU(tanU)]

Where g = acceleration due to gravity

Q = coefficient of frictionWhen do we use +ve and ve


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Uphill mv+(+ve)

downhill mv+(-ve)

For a level surfaceS = V12 V22/2gQ


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APPLICATION: ACCIDENT ANALYSIS

We can use the concepts to analyze an accident thathas occurred._the length of skid marks on the road surface provide

important clues to the accident investigator, sincethey can be used to estimate the speed of the vehicle

that was braked accurately.y One parameter we need is the coefficient of friction,which can be determined by field tests, the otherparameter is the inclination ( by surveying).

y

The estimate that can be made is the speed at themoment skidding began and not necessarily of thespeed at which the braking began.The length of the skid marks after an accidenton a level stretched be SA


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Then V1=SA*2gQ+V22

V1uSA*2gQ(since V2u0)

Let the legal speed limit be VL

The speed limit was exceeded if

SA"VL2/2gQ

NB: suppose SAVL2/ 2g(we can not be sure that speedlimit was exceeded because after braking skid markscan come later.

y So SAdoesnt represent skidding distance)


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STOPPING DISTANCEy Includes distance traveled during PIEV time + braking

distancey Ex: the driver of a vehicle traveling at 80km requires

8.5m(measured horizontally) less to stop afterapplying brakes upgrade than when traveling down thesame.

y If the coefficient of friction is 0.55, calculate the

percent of the gradient (inclination)


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uphill downhill

Distance to stop

=d-8.5mV1=80km/hrV2=0


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Uphill: Su=V12=V22/2g cos U (tanU)

Or

du=ScosU =V12V22 . cos U

2gcosU(tanU)

du = V12V222g(+tanU)

Downhill : sd= V12V22/ 2gcosU (Q-tanU).cosU

sd= V12V22/ 2g (Q-tanU)


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After calculations, V1=22.2m/s

TRAFFIC STREAM CHARACTERISTICS

yA traffic engineer mainly deals with the methods ofcontrolling traffic and related fields studies.

y To do this the behaviors and characteristics of thetraffic stream have to be studied and understood.

V12 - V1

2 = 8.5

2g(-tanU) 2g(+tanU)


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Fundament traffic stream relation ship

Speed (u)= distance [km/hr]

TimeVolume (q)= number of vehicle passing a point ingiven time

=N0 of vehicles

TimeDensity (k)= number of vehicles occupying a unit

distance of road= N0 of vehicles

DistanceFundamental relationship q=u .k


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Related parameters

Time headway: The interval of time from head to head

of successive vehicles as they pass a pointtime = 1

number q

Space headway(s): Distance between head to head of

successive vehiclesDistance = 1

Numbers k


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Speed density relationship

Speed(u)

density(k)

y With increase in density the speed decreases.

y When there are no vehicles (density =0) the speed

is maximum and it is called free speed (uf)yAt very high density the vehicle is called jam

density(kj)


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Speed-volume relationship

volume

speed

u(optimum) uf

y At very low speed the volume traffic will be low.

y W

ith increasing speeds traffic volume also increases up to acertain limit as the space headway initially decreases.

y But as the speed is further increased the spacing between theheadway increases, thus decreasing the volume.

y Optimum speed is at which the volume is maximum.

hmax


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Volume-density relationshipyAs the density from zero, when there is novehicle, the volume increases to a point of

critical density at which the volume ismaximum

yThere after, the volume decreases as the

density increases to a maximum value calledjam density (kj)(when all vehicles are almoststopped)


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volume

Density(k)

(q)qmax

Ko Kj


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Green shields straight time

relationshipq=uk(a)Green shields straight time relationshipK +u =1(b)Kj uf

U=(1- k)uf. k +u=1

Kj kj uf


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y

y uf

density(k)

kjsubstituting into (a)

q=(1- k)uf.k

kjat qmax, dq =0

dk

speed


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q=(1- k)uf.kkj

q=(ufk-k2uf)

kjdq =uf-2kuf =uf(1-2kj)=0 Ass: trafficdk kj kj velocity and distanceat fmax, dq =0, 1-2k =0,k0=kj value of U

dk kj 2U0=uf

2K0=kj qmax=u0k0(maximum volume when we have optimum

speed)2

U0=uf

2

E ample the follo ing is the densit speed data obtained through a traffic


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Example: the following is the density-speed data obtained through a trafficstudy

When we have 100v/km they have average speed of 5km/hr

Speed(km/hr) Density(veh/km)

60 10

50 20

45 30

40 40

35 50

30 60

20 70

15 80

10 905 100

Speed-density data


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a)Plot a scatter diagram Speed(u)Speed

density(k)

100

b)Determine the regression equation and find multiplyingand additive constants.This can be found by LEAST SQUARES METHOD

Let the equation of the line be y =ax+bY:dependent variable(speed)X:independent variable (density)a: additive constantb:multiplying constant


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This can be found by LEAST SQUARES METHODLet the equation of the line be y =ax+b

Y: dependent variable (speed)X: independent variable (density)a: additive constantb: multiplying constant

_ _a= y----bx

_ _b=x1y1=xy- Nx y

_

y12= x2-N(y)2_

x12 = x2-N(x)2


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Volume

y X y2 x2 Xy

60 10 3600 100 600

50 20 2500 400 1000

45 30 2025 900 1350

40 40 1600 1600 1600

35 50 1225 2500 1750

30 60 900 3600 1800

20 70 400 4900 1400

15 80 225 6400 1200

10 90 100 8100 900

5 100 25 10000 500


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y =310, x = 550, y2 =12600, x2 =38500_ _

xy =12100,x=55,y=31,N=10 x1y1 = 12100-10*31*55

=-4950 y12 = 12600-10*(31)2

= 2990 x12 =38500-10(55)2

= 8250

b = -4950 = -0.68250

a = 31-(-0.6*55)the equation of the line is y=64-0.6x(that best fits the points)r =-4950 = -0.996 the speed is inverse proportion density8250*2990


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Significance of r

If r = 1 perfect relationship

r = 0 no relationshipr (+ve) directly proportional

r (-ve) inversely proportional

c) convert the data into speed-volume data

Speed(u)

Volume(xy)q


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d) plot speed volume data

e) find the equation for speed-volume curve.

What is the equation of that curve

u

q


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Equation of speed density is y = 64-0.6x or u =64-0.6k(density)

If q = u.k then k=qu

By replacing : u = 64-0.6 q

u

u2 = 64u-0.6qor

u2 = 64u+0.6q=0


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f) Determine optimum speed, jam density and freespeed.

the equation is u=64-0.6k(1) at jam density u = 0Replacing kj= 64 =107vehicle /km(jam density)

0.6K0=kj = 107 =54vehicle/km(optimum

density)At free speed k=0Replacing in (1) uf=64km/hr(free speed)Optimum speed uf =u0=64 =32km/hrg) convert data for time headway and space head

wayheadway h =1/q and space way S=(1/k)


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q=u.k km/h .v/km v/hr

1 = 1 =1 .hr

q v 1 veh

hr

1 =

600v/hrh =1 = 1 =3600 =6 sec (after 6 sec a vehicle q

q 600 600 passes the time

required for a vehicle topass after another

passing)


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Distance discovered between two vehicleDensity :number of vehicle per unit distance(km)Then put (2) into(1) we get0=64-0.6kKj =64 =640 =106.67

0.6 6 $107 vehicle/km jam densityK0 =kj = 107 = 53.5~ ~ =54veh/km optimum density

At free speed k=0(3)Put (3) into (1)u=64-.6*0 Qf =64km/hr free speed

Q0 = Qf = 64 =32km/hr optimum speed~ ~

S


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g) convert data for time headway and space headway

solution:

calculation of 1for time headway.

q

calculation of 1for time headway.k


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k=x(den

sity)

xy=q

(1/2)h(1/2)

S(1/k)

10 600 1/600

1/1020 1000

1/10001/20

30 13501/1350

1/30

40

50

60

70

80

90

100500

1/500 1/100


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Example: h = 1 = 1 =3600 = 6sec(hr/veh)

Q 600 600 veh

S = 1 km/veh(unit of S) 100m/veh10


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INTERSECTION CONTROL

A highway intersection : A location where morethan one streets intersect either at grade or grade

separated.grade roads intersect at same level

grade separation: one road passes over the other atdifferent levels(one road is above the other) .


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A-share right of way at grade intersection withconflicting traffic movements.

The objective of intersection is to control or

reduce the number of conflict points.


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32 conflict points


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8 conflict points


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TYPES OF CONFLICTSy Crossing Conflict


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y Merging conflict Diverging conflict


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Types of Intersectionsi)Cross Intersection ii)T-Intersection iii)Y-Intersection


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Types of Intersections contdy iv. Skewed Intersection v. Round about


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Types of Intersections contd

yvi) Multiple crossing vii) Railway crossing


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CONTROL MEASURESy 1) Right-of way rule (uncontrolled)

(1) major/minor road

(2) First come

(3) On right


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CONTROL MEASURES2) Signingy

Stop and Yield signs3) Manual controly Traffic controlled manually by uniformed police

officer.

4) Signalizationy Using lights to control traffic at intersections which

cannot be adequately controlled by signs.5) Grade separationyAt intersection one road passes over the other (at

separated level)6) Street closurey One street is closed the other is allowed.


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o This the concept of minor and major street, or two waystop intersection control

o The driver on a minor street yield or give way to thevehicle in major street

o In two-way stop the vehicle select a gap in a priority flow

through which to execute the desired movement.

o The term gap refers to space between vehicles on theroadway that has a right-of-way

STOP OR YIELD CONTROL

75


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o Capacity of the minor street depends on two factors;

The distribution of available gaps in the major streettraffic stream, which depends on the total volume of traffic on the

street, number of lane, and degree and type of platoon on the

traffic stream

The gap size required by minor-street drivers to execute thedesired movement , which depends on the type of maneuver (left,

through, right ) number of lanes, the speed of major street traffic,

sight distance, length of time the minor street vehicle has been

waiting, and drivier characteristics (reaction time, age, etc)


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oAll-way-Stop control concept;

All driver must come to completed stop. The decisionto proceed is based part on the rule of the road, which

suggest first come first serve rule

o All-way-Stop control is considered better method for respecting

NMT priority at the intersection. However the movement of vehicle is relative slower.


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INTERSECTION CONTROLyANALYSIS OF ISOLATED INTERSECTION WITH FIXED

TIME TRAFFIC SIGNALS

y In designing an intersection, Isolated intersections aredesigned differently from coordinated intersectionsy 1 2 3


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ISOLATED INTERSECTION

y Traffic flow and hence intersection design areindependent of any other nearly intersection


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COORDINATED INTERSECTION

y Traffic flow and design depend of other nearbyintersections.

y Fixed time : signal timings are fixed (the samethroughout)

y

Traffic actuated signals: Signal timings automaticallydepending on trafficy 1 2 3

SIGNALISATION!!


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SIGNALISATION!!yObjectives

yBasic Rule

ySignal phasing (phasing schemes)

y

Phasing at IntersectionsyTraffic Analysis Proceedure

yDesign of traffic Lights with examples

y

Choice of selection and cycle lengths(Crucial as it is, this part of the module has

been spared for next weekend - whole day!)

PEDESTRIAN AND BICYCLE


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PEDESTRIAN AND BICYCLE

CONCEPT


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o Pedestrian speed is the walking speed, in m/s.

o Pedestrian flow per unit of width is the average flow of pedestrians per

unit of effective walkway width, expressed as pedestrians per minute

per meter (p/min/m).

o Pedestrian density is the average number of pedestrians per unit of

area within a walkway or queuing area, expressed as pedestrians per

square meter (p/m2).

o Pedestrian space is the average area provided for each pedestrian in

a walkway or queuing area, in (m2/p).

o Platoon refers to a number of pedestrians walking together in a group,

usually involuntarily, as a result of signal control and other factors.

PEDESTRIAN CONCEPT


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o Qualitative measure, such as freedom to choose desired

speeds and to bypass others is similar to vehicles

o Environmental factors that contribute to the walking

experience such as comfort, convenience, safety,

security, and economy of the walking system influences

the LOS

o Comfort factor include, weather protection, climate

control, arcades, transit shelters, pathway directness,

grades, sidewalk ramps, directional signing, direction

map etc

PRINCIPLES OF PED

ESTRIAN FLOW


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y Safety is provided by separation of pedestrian from

vehicular traffic on the horizontal plane, vertically by

provision of above and below with overpass and

underpass

y Security is provided by street lighting, free space on the

walkway, less activity on street.

y Economic include the user cost incurred by travel delay

and inconvenience

PRINCIPLES OF PEDESTRIAN FLOW


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o Speed-Density relationship:

As volume and density increase, pedestrian speed declines.

As density increases and pedestrian space decreases, the

degree of mobility of pedestrian declines

PEDESTRIAN FLOW MEASURES

Jam


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o Flow-Density Relationship:



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o Flow-Space Relationship:

The condition of max flow represent the capacity of the walkway

facility

Narrow range of density varies from 0.4-0.9m2/p. But at less than

0.4m2/p, flow decline significantly



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o Speed-Space Relationship:

The study below indicates that at space < 1.5m2/p, even slowest

pedestrian cannot achieve the desired walking speed.

Faster walking pedestrian at 1.8m/s needs at least 4.0m2/p or

more



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o The designer should use pedestrian body depth and shoulder

breadth for minimum space

o Simplified body ellipse of 0.5m x 0.6m = 0.3m2 is used as basic

space for a single pedestrian. However, 0.75m2 is used as buffer

zone for each pedestrian

PEDESTRIAN SPACE REQUIREMENT


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o Pedestrian requires certain amount of forward space during walking.

The forward space is critical dimension because it determine the

speed of the trip and number of pedestrian that can pass a point in a

given time

It is categorized as pacing zone and sensory zone

PEDESTRIAN SPACE REQUIREMENT


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o Walking Speed highly depends of the combined age group in the

walking population, grade and effective width

0-20% of elders (65yrs or more) makes an average speed of

1.2m/s in a walkway

IF is > 20% in walking population the speed decreases to 1.0m/s

A grade of 10% of more reduces the speed by 0.1m/s

Higher number of Children's

Street lights, trees etc installed in the walkway

AVERAGE PEDESTRIAN WALKING SPEED IS 1.5m/s

PEDESTRIAN WALKING SPEED


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o Pedestrian start-up time of 3s is taken as an average crosswalk at

traffic signals

o A capacity of 75p/min/m or 4500p/h/m is taken as values for

pedestrian facility if local data is not available

o Typical free flow walking speed distributions

PEDESTRIAN START-UP TIME & CAPACITY

93


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o The lane width is used to determine how many people can walk

abreast in width of a walkway

o The minimum walkway width should permit two pedestrian to pass

each other

o To avoid interference each pedestrian should have at least 0.8m of

walking width. i.e. 0.7m occupancy and 0.1m allowing a likelihood of

contact due to body sway, unless if it is very clouded

o Moving pedestrian shy away from the edge curb and against the

wall. Therefore, un used space must be discounted when analyzing

pedestrian facility

PEDESTRIAN EFFECTIVE WIDTH


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o The strip preempted by pedestrian standing near the

building, or physical obstruction such as light pole,

garbage box, advert post should be excluded.

o The obstructions in the walkway reduces the effectivewidth. Although single point obstruction would not reduce

the effective width of entire walkway, but it affect that

immediate vicinity

o Designer should liaise with utilities authorities in the

appropriate location of these physical obstructions

PEDESTRIAN EFFECTIVE WIDTH


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o Speed is important LOS criteria because it can be observed and

measured easily.

o The conflict in crossing pedestrian streams is analyzed in study

below.

PEDESTRIAN LEVEL OF SERVICE, LOS

Speed 1.8m/s


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97


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Just like for vehicles

LOS A LOS C


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LOS D LOS F


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o Sample pedestrian volume at 1.5m sidewalk



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o Bicycle lane should be separated from vehicle lane.

o The capacity and LOS of bicycle facility depend on the

number of effective lane used by bicycles

oAASHTO recommends 3m wide lane, with minimum of

2.4m in low volume conditions

o Because of poor facility in Rwanda, most bicyclists

unsafely use the vehicle lane.

o In Europe, for two-way lane the capacity is 1600b/h/ln or

3200b/h/ln in one-way lane.

BICYCLE CONCEPT


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o The concept of hindrance is related to comfort and

convenience of bicyclists

o The mixed of pedestrian and bicyclists provide hindrence

BICYCLE LEVEL OF SERVICE

103


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o The LoS for uninterrupted flow



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o Typical facility for residential areas



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o Typical facility for Urban areas



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o Typical facility for Rural Areas



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o Lack of NMT Consideration

LACK OF NMT FACILITY IN RWANDA


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o Un considered NMT in Rwanda

LACK OF NMT FACILITY IN RWANDA


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INTERSECTION CONTROLyANALYSIS OF ISOLATED INTERSECTION WITH FIXED

TIME TRAFFIC SIGNALS

y

In designing an intersection, Isolated intersections aredesigned differently from coordinated intersectionsy 1 2 3



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y Traffic flow and hence intersection design are

independent of any other nearly intersection



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y Traffic flow and design depend of other nearby

intersections.y Fixed time : signal timings are fixed (the same

throughout)

y Traffic actuated signals: Signal timings automaticallydepending on traffic

y 1 2 3

SIGNALISATION!!


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yObjectives

yBasic Rule

ySignal phasing (phasing schemes)

yPhasing at Intersections

yTraffic Analysis Proceedure

yDesign of traffic Lights with examples

y

Choice of selection and cycle lengths


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yThey reduce frequency of certain types of

accidents (particularly right-angle collisions)

yUnder conditions of favorable spacing, they

can be coordinated to provide for continuousor nearly continuous movement of traffic at adefinite speed along a given route

yThey can be used to interrupt heavy traffic atintervals to permit other traffic, pedestrian andvehicular, to cross


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yThey represent a considerable economy, ascompared with manual control, atintersections where the need for definitemeans of assigning right-of-way first to one

movement and then to another is indicated byvolumes of vehicular and pedestrian traffic orby the occurrence of accidents.

yTraffic signals can however have certaindisadvantages!.


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y Traffic flow and hence intersection designs are

independent of any other nearly intersection



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y Traffic flow and design depend of other nearby

intersections.y Fixed time : signal timings are fixed (the same

throughout)

y Traffic actuated signals: Signal timings automaticallydepending on traffic

y 1 2 3


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Signal cycle: A complete sequence of signal


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g y p q gindications .

Cycle: when you have allowed every movement before you start again.

Cycle length :time required to complete a

cycle.y A signal time scheme is dependent on

lane configuration at the intersection

(number and arrangement of lane turning atthe intersection) - depend on whetherseparate turning lanes are available or not

PHASING: Eg:


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unsignalised p1 phase 1 phase 2

fli


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:conflict

movement (allowed)

blocked movement

yAll direct crossing conflicts are separated

y Indirect crossing conflicts caused by turning

movement may or may not be in different phases.


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PHASING SCHEMES(number of phases)

2_phase scheme: This is the basic

phasing scheme for any intersection. For analysis firstcheck if this works - if it does notthen go to another scheme.


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3_phase scheme : Type A


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Separate lane for turning Phase 1

Phase2 Phase3


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PHASING AT INTERSECTION


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2phase scheme

3phase scheme type c

Ph1 ph2 ph1 ph2 ph3


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ANALYSIS PROCEDURE


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ANALYSIS PROCEDURE

If we are given an existing intersection and we are

asked to design a suitable phasing scheme.

There are several steps:

STEP1: identify lane geometry

STEP2: determine hourly volumes

STEP3: through traffic plus left turns at the amber

(yellow)

STEP3 is done if the left turns are sharing the

same phase with through traffic from the opposite

direction

WN


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ySuppose we have the above movements(through) and left turns sharing the same phase.

y You have to check if the intersection canaccommodate through traffic and left turns inone phase. Because we may have heavy throughtraffic without gaps so left turns can not go.

LN

Ls

Ws

y The left turns in phase 1 can be accommodatedduring the green plus amber periods


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during the green plus amber periods

If : WLi -7200 < 1200 [ ULi ]C n

7ULi

i=1

Where: WLi = max[WN+LS;;WS+LN]C = cycle length

ULi = critical lane volume in phase i1200=is the max left turns and through

movements which can pass the intersection duringthe green in one hour.

Critical lane volume UlConsider the following arrangement

UL U L / U i


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UL=Umax+Lmax+1/2Umin

Umax= The highest of Un and Us.The same for Li

1 is affected by two and 2 is also affected byopposite through traffic.

Umax= max (Un,Us), Lmax = max(Ln,Ls)

Umin= min (Un, Us)

LsUN

Us

1

2

LN


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LN Us1 Us2UN2 UN1

Ls

UL=max [UN2+Ls+1/2Us1 ]Us2+Ln+1 UN1

2U1max+Lmax+1U1min

2

Green + Amber + Red=cycle length.(yellow)

2L Turns can be allowed during amber (yellow). 2 vehicles turning left

How many left turns can be allowed in one hour during yellow time?

= 2x3600 (This has to be deducted from UL)

C in seconds

2L Turns can be allowed during amber (yellow). 2 vehicles turning left

How many left turns can be allowed in one hour during yellow time? (depends onhow many yellows indications in one hour)


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how many yellows indications in one hour)

2x3600

C(in seconds)Example: Suppose you have the following intersection

Which scheme will be appropriate for this intersection?

60 2 4 106 0

28 274

374 248

490 140160 226 5 0 210


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For Phase 2: Wl2 = max [2 + 4 + 226]


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For Phase 2: Wl2 = max [2 + 4 + 226]8 + 0 + 106

= 232UL2 = 8 +226 + (4)= 236

CheckPhase I: 1004 7200


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9

274

28 248

106

374 2 4

490 8 0140 226

Q1 Q2 Q3


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288 274374 248


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374 248490 140 106

2 4Q1 Q2 Q3 8 0226

1 2 3Wl1= WL2=

WL3= 232Ul1= 490 UL2= 274 UL3= 236

No need to check 1 and 2: because no opposing through.Check 3: 232 < 1200 236

490 + 284 + 2363 Phase Type B is SATISFACTORY


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SELECTION: Total critical lane volumes s

Type A = 60 + 490 + 236 = 786

Type B = 490 + 274 + 236 = 1000

transportation eng 2 (notes).pptx repaired]

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