Driver perception response time during the signal change interval.

The importance of perception response time (PRT) values for traffic signal change interval design, and the need to monitor the design PRT value, are challenges facing transportation professionals. However, current methods used to validate the design PRT value from on-site observational studies have failed to yield convincing proof that the 1 second design value is adequate. A modification to on-site data capture and extraction, using a transitional zone (TZ), is used to overcome this deficiency. The TZ allows the systematic identification and exclusion of those drivers who have time to delay their responses. Their inclusion in past studies inflated PRT values. Their exclusion in this study provides a more accurate value.