components of ts i

COMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMPrimary components of the traffic system:

d (d d b l )Road users (drivers, pedestrians, bicyclists, passengers)

V hi l ( t k h hi l b )Vehicles (passengers cars, trucks, heavy vehicles, buses)

Streets and Highways (horizontal and vertical alignment)Streets and Highways (horizontal and vertical alignment)

Traffic control devicesTraffic control devices

The general environmentThe general environment

Notice:The general environment has an impact on traffic operations but it is difficult to estimate.

Traffic engineers have little control over driver and vehicle characteristics, design of roadway systemsand traffic controls is in the core of their professional practice

COMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEM

involved drivers pedestrians bicyclists passengers

ROAD USERSROAD USERSinvolved - drivers, pedestrians, bicyclists, passengers

bicyclists

pedestrians

drivers

HUMANSHUMANSpassengers

COMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEM

HUMANS FROM THE POINT OF

ROAD USERSROAD USERS

- ActiveActive part part oror traffictraffic systemsystem

HUMANS FROM THE POINT OFVIEW OF TRAFFIC ENGINEERING

pp yy-- HumanHuman responseresponse isis aa majormajor componentcomponent ofof

planningplanning andand designdesign ofof transportationtransportationsystemssystemssystemssystems

-- HumanHuman beingsbeings havehave aa widewide rangerange ofofcharacteristicscharacteristics thatthat influenceinfluence thethe drivingdriving tasktask( i i( i i titi titi h ih i h i lh i l t htt ht(vision,(vision, reactionreaction timetime,, hearinghearing,, physicalphysical strenghtstrenght,,personality)personality)

-- AA majormajor tasktask isis toto findfind howhow toto givegive driversdrivers rightrightjj gg ggiinformationnformationss inin aa clearclear andand effectiveeffective wayway withwithproperproper responsesresponses

-- EngineeringEngineering designsdesigns generallygenerally accommodateaccommodate thethe-- EngineeringEngineering designsdesigns generallygenerally accommodateaccommodate thetheabilitiesabilities ofof 8585%% ofof usersusers

COMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMROAD USERSROAD USERS

HUMANS FROM THE POINT OFHUMANS FROM THE POINT OFVIEW OF TRAFFIC ENGINEERING

Which characteristics of drivers are mostWhich characteristics of drivers are mostimportant in transportation?

VISIONVISION and REACTION TIMEREACTION TIMEN iNotice:There are other important characteristic – hearing (i.e. horns, sirens), physical strenght (steering, braking – not actual in passengers cars),physical strenght (steering, braking not actual in passengers cars), personality or psychology of the driver (very difficult to quantify)


VISUAL FACTORSROAD USERSROAD USERSVISUAL FACTORS

a. Visual acuitya. Visual acuity(is the ability to see fine details of an object)

FIELDS OF VISIONstatic (observation of stationary objects)- depends on brightness- increases with an increase in illumination - depends on contrast- time of focus (0.5 to 1.0 second)

d i (d t ti f i bj t )dynamic (detection of moving objects):- clear vision cone 3 to 10°- fairly clear vision cone 10 to 12°- peripheral vision is the ability of people to

AFFECTS:

p p y p psee objects beyond the cone of clearest vision(160 °). Can see objects but no details andcolor are clear.

PLACING OF PRAFFIC SIGNS (places, height, distances, design),

SPEED ESTIMATION (important for pedestrians on pedestrian crossings or drivers within iintersections)

COMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMROAD USERSROAD USERSVISUAL FACTORS

dd. Color vision:. Color vision:(the ability to determine one color from another)(the ability to determine one color from another)

- Color blindness is the deficiency of this ability- The eye is more sensitive to the combinations of black and white and black and

yellowyellow

cc. Glare recovery:. Glare recovery:(the ability of a person to recover from the effects of glare after passing the light source)F d k t li ht 3 d f li ht t d k 6- From dark to light: 3 sec and from light to dark: 6 sec

dd. Depth perception:. Depth perception:(the ability of a person to estimate speed and distance)(the ability of a person to estimate speed and distance)

- Very important for passing maneuvers in two-lane roads- Traffic control devices are standardized to aid in distance estimation

COMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMROAD USERSROAD USERSVISUAL FACTORSVISUAL FACTORS

OTHER VISUAL FACTORS


REACTION TIME OF THE DRIVERS

ROAD USERSROAD USERSREACTION TIME OF THE DRIVERS

(PRT – PERCEPTION REACTION TIME)

REACTION TIME INVOLVE 4 PHASES:REACTION TIME INVOLVE 4 PHASES:Detection – object enters the driver´s field of visionIdentificaion – driver acquires information about objectDecision – driver analyzes the information about objectResponse – physical reaction of the driver

Design values: 1,5 s – 2,5 s (which involves braking reactions)


REACTION TIME OF THE DRIVERS

ROAD USERSROAD USERSREACTION TIME OF THE DRIVERS

FACTORS AFFECTING THIS PROCESS

Environment: Urban vs. Rural, Night vs. Day, and Wet vs. Dry Age Physical Condition: Fatigue and Drugs/Alcohol Medical condition Visual acuityy Ability to see (lighting conditions, presence of fog, snow, etc) Complexity of situation (more complex = more time)

E t d i ill t i kl t it ti th Expectancy: drivers will react more quickly to situations they expect to encounter as opposed to those that they do not expect to encounter


BASIC CHARACTERISTICS OF THE PEDESTRIANS

ROAD USERSROAD USERSBASIC CHARACTERISTICS OF THE PEDESTRIANS

WALKING SPEEDS

Most of interactions between pedestrians and vehicles occur as pedestrians cross the roads at intersections or mid – block locations.

Pedestrian walking speed in pedestrian crossing is the most important factor in theconsideration of pedestrians in SIGNAL TIMING.

WALKING SPEEDS

Note that traffic lights are designed not only to allowed vehicles to pass through theintersection but also to allowed pedestrian to cross.

Desing values could vary from 1 – 1,5 m/s.

15 m

Walking speed = 1,5 m/secTotal time to cross the street =?


BASIC CHARACTERISTICS OF THE PEDESTRIANS

ROAD USERSROAD USERSBASIC CHARACTERISTICS OF THE PEDESTRIANS

GAP ACCEPTANCE OD THE PEDESTRIANS

Time intervals between vehicles arriving to the unsignalized pedestrian crossingTime intervals between vehicles arriving to the unsignalized pedestrian crossing and the behaviour of pedestrians in accepting them to cross through.

Desing values could vary from 35 – 50 m.

Note: a traffic light is designed not only to aloud vehicles toNote: a traffic light is designed not only to aloud vehicles topass through the intersection but also to aloudpedestrian to cross.

If i il bl ithi i t tiIf no gap is available within an intersection or onstreet then alternatives arrangements such aspedestrian signals may be considered.

COMPONENTS OF TRAFFIC SYSTEMCOMPONENTS OF TRAFFIC SYSTEMVEHICLESVEHICLES

involved passengers cars trucks buses motorcycles

DESIGN VEHICLE

involved – passengers cars, trucks, buses, motorcycles, bicycles – ALL TYPES OF VEHICLES

Design vehicles are used for setting up turning roadways, intersection curbs and lanewidths.

Desing vehicle is the largest vehicle which couldDesing vehicle is the largest vehicle which could operate on designed roadway.

and has three basic characteristics:- Static characteristics:

- Weight - Size

Turning radius- Turning radius- Kinematic characteristics:

- Acceleration- Dynamic characteristics:

P / i ht ti- Power/weight ratios- Braking Distance


STATIC CHARACTERISTICS OF THE VEHICLESSTATIC CHARACTERISTICS OF THE VEHICLESSIZE, WEIGHT

This characteristics depends on legislation ineach country (max sizes and weights ofvehicles)

Usually are vehicles divided into three or four main categories:

- Passenger carsB- Buses

- Trucks- (special vehicles)


STATIC CHARACTERISTICS OF THE VEHICLESTURNING CHARACTERISTICS

LOW SPEED

STATIC CHARACTERISTICS OF THE VEHICLES

- NEEDED FOR ESTIMATING THE MINIMUM TURNING RADIUS- Low – speed turns are limited by the steering mechanism in vehicles

d b l 30 k /h- speeds below 30 km/h

HIGH SPEED- NEEDED FOR ESTIMATING THE MINIMUM CURVE RADIUS- High – speed turns are limited by the dynamics of side friction between roadwayand tires, and by the superelevation- speeds above 30 km/h

DISCOVER AUTOTURN


KINEMATIC AND DYNAMIC CHARACTERISTICS OF THE VEHICLES

VEHICLESVEHICLESKINEMATIC AND DYNAMIC CHARACTERISTICS OF THE VEHICLES

Critical characteristic – express the ability of the vihicle to stop or decelerateBRAKING AND DECELERATION, ACCELERATION

deceleration considered

, a2

2nV

BD

Basic equation:

Derived equation:

deceleration considered as 1,7 - 2 m/s2

acceleration considered as 1,2 m/s2

DB=Vn or (Vi – Vf)Derived equation:

where: vn is design speed [km/h], vi is initial speed and vf is final speed [km/h],gn is normal gravitational acceleration 9,81 m/s2, a is acceleration rate m/s2

fv is breaking force coefficient (wet pavement, tire profile 1,6 mm),fv is breaking force coefficient (wet pavement, tire profile 1,6 mm),s is longitudinal slope [%],DB is breaking distance,

vn km/h 130 120 110 90 80 70 60 50 40 30

fv 0,32 0,34 0,36 0,40 0,43 0,46 0,51 0,56 0,62 0,68

components of ts i

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