An investigation of the relationship between total and stopped delay at signalized intersections

Abstract

This thesis investigated the relationship between total delay and stopped delay at signalized intersections. As the 1.3 value used in the 1985 HCM was obtained empirically, an analytical model was developed to account for the relevant variables such as approach speeds and associated deceleration and acceleration rates. By studying the effects of the relevant parameters, the relationship between delay components was analyzed with respect to the different operating conditions at signalized intersections. The TRAF-NETSIM computer simulation program was used to provide reference values for the results from the analytical model under the same operating conditions. Actual traffic delay data were collected in the field to validate the model's results. Statistical analysis was used as an important tool to achieve this goal. The results from this study indicated that the ratio of total delay to stopped delay was not a constant as the operating conditions changed. Specifically, as approach speed increased, this delay ratio increased when other parameters were assigned reasonable values. A similar trend was observed from the field measurements. The reason for this phenomenon is that higher deceleration or acceleration rates are generally used by most drivers to decelerate from or accelerate to higher speeds,thus changing the composition of total delay. In conclusion, the ratio of total delay to stopped delay should not be treated as a constant and should be calculated using an appropriate model.