Evaluation of present and future traffic situation is carried out for estimating the level of service through a lot of traffic indicators (such as Saturation Flow, capacity, delay and travel time), but all these indicators are based primarily on the
measurement of Passenger Car Unit (PCU) .This paper analyzes the impacts of
four different types of vehicles on the capacity of signalized intersections. Data was collected at five intersections in Damascus city, and estimates of mean headways associated with four different types of vehicles, as well as passenger cars. Using the estimated headways, Passenger Car Equivalents (PCEs) were
calculated, and these suggest that the impacts of these types should be given special consideration when analyzing the capacity of signalized intersections.
The evaluation of the capacity of signalized intersections is one of the most important
parameter used in the planning, design, operation and management of urban street
networks. The calculation of capacity depends on the estimation of the saturati
on flow of
the signalized intersections.
The highway Capacity Manual (HCM 2010) is used to estimate and analyze the saturation
flow. This method is widely used in many countries around the world, including Syria. It
reflects the local conditions in the United States of America; therefore it may not be
suitable for use in our local conditions.
This study includes estimation of the field saturation flow depending on the headways
between the vehicles in the queues, and comparing the field results of the saturation flow
with the values resulting from using the HCM. The study was conducted on three
intersections in the Tartous city. The analysis was based on data collection using video.
The final results confirmed that there is a clear difference between the field measurement
of the saturation flow and computation value, Which confirms that it cannot be used for
our local conditions.
