Abstract:
Passenger Car Unit (PCU) or Passenger Car Equivalent (PCE) is a metric used
in Transportation Engineering, to assess traffic-flow rate on a road or an intersection. A
Passenger Car Equivalent is essentially the impact that a certain mode of transport has on
traffic variables compared to a single passenger car.
Roads in Sri Lanka carry heterogeneous traffic, where road space is shared among many
traffic modes with different physical dimensions and prevailing loose lane discipline.
PCU factors used in Sri Lanka at present are somewhat older and do not reflect static and
dynamic characteristics of modern vehicles, road conditions or driver behavior.
Data collection was done on various four lane road segments. Location for the study is
identified based on uniformity of road characteristics in terms of pavement width, shoulder
type, etc. There should be no visual obstructions to traffic because of bus stops, road side
developments, etc. No intersection or side roads along the road stretch so that there are no
changes in the traffic volume over the entire stretch. No signalized intersection for 3km road
length.
Traffic volume data was collected using video camera to record vehicles in both directions
during peak hours. These video footages were observed and the traffic volumes, speeds and
85% value of road width used by traffic volume were calculated.
Then using modified density method proposed by Tiwari (Tiwari, Fazio, & Pavitravas), the
PCU factors were derived.
𝑃𝐶𝑈𝑋𝑖 =
𝑘𝑐𝑎𝑟
𝑊85𝑐𝑎𝑟
β
(
𝑞𝑥𝑖 𝑢𝑥𝑖
β )
𝑊85𝑥
The results obtained, showed that there is a variation from homogenous conditions to
heterogeneous conditions. These results can be used for traffic volume analysis, capacity
calculations, road network planning and design purposes, etc. in Sri Lankan four lanes
roads. Further research can be carried out to evaluate PCU factor for 6 lane roads, different
highways and intersections.
Citation:
Weerasinghe, W.A.M.A.B., & Pasindu, H.R. (2015). Development of PCU factors for four lane roads under Sri Lankan context [Abstract]. In H.R. Pasindu (Ed.), Proceedings of the Transportation Research Forum 2015 (pp. 19-17). Department of Civil Engineering, University of Moratuwa. https://uom.lk/sites/default/files/civil/files/TRF%202015_0.pdf