An analysis of the start-up delay and safety for signalized intersections: Impact of left-turn phasing sequences

Abstract

This paper aims to investigate the start-up delay at signalized intersections in Abu Dhabi (AD) city, UAE. The impact of some external factors that may affect the start-up delay in examined including; left turn phasing sequences (split/lead/lag), movement turning (through/left), intersection location (CBD/non-CBD) and day time (peak/off-peak). The paper also addressed the impact of illustrating lead/lag phasing system on the performance of traffic and safety. A significant number of observations were obtained by using automated license plate recognition cameras at 66 different intersection approaches. The results show that the estimated mean value of the start-up delay is 2.201 s with a standard deviation of 1.823 s. In conclusion, the statistical tests show significant difference in start-up delay the have between observed for through, left, at CDB and non-CDB area and between split and lead/lag phasing. However, no significant difference between peak and off-peak periods and between split and lead phasing are recognized. In addition, the lead/lag phasing improved the traffic performance by reducing the total delay at intersections but has a negative impact on the safety.