Keywords: stopped delay, approach delay, control delay, signalized intersections, traffic signals, level of service.

Signalized intersections are the most complicated and critical element of the arterial network system and the most often studied element [1]. Their capacity and level of service are determined by using the analysis procedure presented in the Highway Capacity Manual (HCM) [2,3,4,5]. The earlier versions of the HCM, evaluated the level of service based on the stopped delay [2,3], where the latest versions use the control delay [4,5]. Control delay is defined as the portion of delay attributed to the presence of signalized intersections. It includes the deceleration delay, queue move-up delay, stopped delay and the acceleration delay [5].

This paper presents the development of a procedure to estimate control delay to be used in evaluating the performance of four legs signalized intersections that are manually operated by officers in the developing countries and in research work. This procedure may be used for an approach of a signalized intersection in circumstances that are often exist in the developing countries, where driver behavior differs from that of the industrialized countries. Such drivers are more aggressive and less compliant to traffic rules, and the law enforcement officers are more lenient in enforcing the law. This behavior renders the use of the methods presented in the HCM impractical and establishes the need to develop a method that is more tolerant to driver behavior. The estimated control delay by this procedure includes initial deceleration delay, queue move up time, stopped delay, and final acceleration delay. It includes several tables that were developed to capture the different parts of control delay.

The developed procedure is used to construct the delay scenarios presented in Hurdle's paper to measure the approach delay of a four legs signalized intersections that are manually operated by officers [6]. The procedure utilizes different observers located at specified locations, to count approach arrivals and approach departures, volumes on cycle-by-cycle basis. Vehicle control delay is calculated as the difference in time between the arrival and departure curves, which represents the approach delay, multiplied by a factor of 1.0526 to obtain the control delay [7]. The average number of vehicles in queue is calculated as the difference in the accumulated vehicles divided by the number of lanes in the approach. This procedure will overcome the problems associated with saturated approaches and the difficulties related to identifying the lane groups due to the unmarked approach lanes, which make identifying the lane groups a difficult task. Moreover, it will tolerate the driver behavior that is demonstrated by driving between the lanes, cutting-off other vehicles, forming more lanes on the approaches of signalized intersection than the marked lanes, and the execution of turns from extreme far lanes that require cutting-off other vehicles.

This procedure was tested using a traffic data that was collected for a signalized intersection in the city of Makkah in Saudi Arabia. The traffic data was collected during the morning rush hour from 06:30 to 07:50 a.m. on Wednesday, December 24th 2003. The estimated approach delay was 64 seconds per vehicle for the approach that was investigated. This value is equivalent to 67 seconds per vehicle of control delay. The performance of this signalized intersection for this value of control delay is Level Of Service E according to the HCM.

1

A.D. May. "Traffic Flow Fundamentals". Prentice-Hall, Inc, Englewood Cliffs, New Jersey, USA, 1990.

2

Transportation Research Board (TRB), "Highway Capacity Manual, Special Report 209", National Research Council, Washington D.C. 1985.

3

Transportation Research Board (TRB), "Highway Capacity Manual, Special Report 209", National Research Council, Washington D.C. 1994.

4

Transportation Research Board (TRB), "Highway Capacity Manual, Special Report 209", National Research Council, Washington D.C. 1998.

5

Transportation Research Board (TRB), "Highway Capacity Manual", National Research Council, Washington D.C. 2000.

6

V.F. Hurdle. "Signalized Delay Models: A Primer for the Uninitiated". Transportation Research Record 971, Transportation Research Board, National Research Council, Washington D.C. 1984.

7

C.A. Quiroga and D. Bullock. "Measuring Control Delay At Signalized Intersections". Journal of Transportation Engineering, July/August, 1999. doi:10.1061/(ASCE)0733-947X(1999)125:4(271)

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