If the space headway is 7m, then the jam density in vehicle/km is ______

Parking facilities may be classified into how many types?

One of the disadvantages of traffic signals is?

The number of parking spaces for a kerb of 59m and having the length of car as 5.0m is?

During the construction of highway, more highway lighting preference is given to ______

The traffic population is estimated by ______

The charts showing the variation of the traffic is called ______

What is the first objective of traffic volume studies?