Abstract
This manual describes a computer model which simulates traffic flow on a rural road. The model, and the associated computer program, is referred to by the name TRARR. The model allows overtaking prohibitions, auxiliary lanes, horizontal and vertical curves, and variable sight distance to be studied. Vehicles may vary in performance and drivers may vary in their behaviour when unimpeded, following other vehicles, overtaking or merging. The detailed coding of the computer program was done with three objectives in mind: the behaviour of vehicles should be able to be varied greatly by changing the data without changing the program, the program should be reasonably efficient, and the program should be modular so that it may be easily modified.