Appendix G 5.3 Pedestrian Clearance Time
The purpose of the pedestrian clearance time is to allow pedestrians, who have stepped off the kerb at the commencement of the pedestrian clearance interval, to complete their crossing with safety. It comprises Clearance 1 and Clearance 2 intervals as seen in Figure G 2 and Figure G 3.
The pedestrian clearance interval is implemented using a flashing don’t walk display. However, during the intergreen interval terminating the phase, the flashing don’t walk or steady don’t walk displays can be used as part of the clearance period (except, in some jurisdictions, only the steady don’t walk may be displayed when filter right turns are allowed with parallel pedestrian movements).
1. Calculate the total clearance time (in seconds) from:
|tpc = Lpc / vpc subject to tpc ≥ 5||A5|
|tpc||=||total pedestrian clearance time (s)|
|Lpc||=||pedestrian clearance distance (m)|
|vpc||=||pedestrian walking speed (m/s)|
2. Determine the durations of the Clearance 1 and Clearance 2 intervals (tc1 and tc2) from:
|tc1||=||tpc – I|
|I||=||intergreen time (s) (Appendix G.4.6)|
|tpc||=||total clearance time (s) from Equation A5|
The pedestrian clearance distance in Equation A5 is based on the length of the marked crossing between kerb lines. Where the sides of the crossing are of unequal length, the length of the longest side is used.
If a median exists, its width is included in the clearance distance when crossing both carriageways in one movement, i.e. the pedestrian clearance distance includes both carriageway widths as well as the median width. However, if the walk time is calculated using Equation A4 for the case when crossing a wide road with a median in one movement, the clearance distance in Equation A5 should be based on the larger of the two carriageway widths (i.e. excluding the median width).
Where a median is wide enough to store pedestrians, a staged signalised crossing can be used. In this case, the crossings are treated separately, and the width of appropriate carriageway is used as the clearance distance for each crossing.
Where an exclusive pedestrian phase is provided at an intersection, the shortest distance between diagonally opposite corner kerb radii for the longest crossing is used as the clearance distance.
The pedestrian walking speed for determining total clearance time is usually 1.2 m/s. In some jurisdictions a walking speed of 1.5 m/s is adopted for the calculation of the Clearance 1 time provided that the flashing don’t walk display does not overlap into the vehicle intergreen period. A clearance speed of vpc = 1.0 m/s may be appropriate for sites with higher populations of slower pedestrians.
Figure G 6 shows the distribution of walking speeds at mid-block signalised crossings in Melbourne (Akcelik & Associates 2001). This indicates that the recommended clearance speeds of 1.0 and 1.2 m/s correspond to 5th and 15th percentile speeds, respectively, i.e. approximately 5% of pedestrians were observed to cross with speeds below 1.0 m/s, and 15% were observed to cross with speeds below 1.2 m/s.