A mathematical model of a road block

The eect of a road block on trac ow is investigated using the model in which the trac velocity is a linear function of the trac density. The road consists of two lanes in one direction and one lane is closed for a short distance by a road block. The length of the tailback at the entrance to the road block, the time spent in the road block and the trac ux at the exit to the road block are calculated. The maximum length of the tailback is a linear function of the time T that the road block was in place. The eect of the road block on the trac depends on three parameters, the density of the oncoming trac, the time T and the ratio of the speed limit in the road block to the speed limit on the open road. The congestion caused by the road block can be managed by adjusting T and .