Module 7 : Traffic Signal Design

Lecture 36 : Special Requirement in Traffic Signal

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	Pedestrian crossing Pedestrian crossing requirements can be taken care by two ways; by suitable phase design or by providing an exclusive pedestrian phase. It is possible in some cases to allocate time for the pedestrians without providing an exclusive phase for them. For example, consider an intersection in which the traffic moves from north to south and also from east to west. If we are providing a phase which allows the traffic to flow only in north-south direction, then the pedestrians can cross in east-west direction and vice-versa. However in some cases, it may be necessary to provide an exclusive pedestrian phase. In such cases, the procedure involves computation of time duration of allocation of pedestrian phase. Green time for pedestrian crossing $G_p$ can be found out by, $$G_p = t_s+\frac{dx}{u_P}$$ where $G_p$ is the minimum safe time required for the pedestrians to cross, often referred to as the pedestrian green time, $t_s$ is the start-up lost time, $dx$ is the crossing distance in meters, and $u_p$ is the walking speed of pedestrians which is about 15th percentile speed. The start-up lost time $t_s$ can be assumed as 4.7 seconds and the walking speed can be assumed to be 1.2 m/s.