TRANSPORTATION ENGINEERING I

DEFINE THE FOLLOWING:

1. TRAFFIC FLOW

- Is the study of interactions between vehicles, drivers, pedestrians, cyclists,

other travelers and infrastructure ( including highways, signage, and traffic

control devices), with the aim of understanding and developing an optimal

road network with efficient movement of traffic and minimal traffic congestion.

2. DENSITY

- Is the number of vehicles occupying a given length of a highway in a traffic

lane. Density is inversely proportional to the volume of traffic. If density is

less, then speed will be more and traffic volume will be more. And if density is

greater, then the speed will be low and traffic volume will be less.

3. TIME MEAN SPEED

-time is measured by taking a reference area on the roadway over a fixed period

of time. In practice, it is measured by the use of loop detectors.

4. SPACE MEAN SPEED

-is the speed measured by taking the whole roadway segment into account.

Consecutive pictures or video of a roadway segment track the speed of individual

vehicles, and then the average speed is calculated.

5. TIME HEADWAY

-time that elapses between the vehicle passing a reference point in space, and

the following vehicle. Practically, it involves the measurement of time between

the passage of one rear bumper and the next past a given point

6. SPACE HEADWAY

-distance between corresponding points of two successive vehicles at any given

time. It involves measurement from a photograph, the distance from a rear

bumper of following vehicle at a point of time.