01550152

Component

Traditionally, highway capacity manual (HCM) incorporates the effect of heavy vehicles (HVs) in forms of passenger car equivalents (PCEs) for estimating traffic conditions on highways. PCEs of heavy vehicles are critical in designing, operating and evaluating highways. Recently, a massive amount of automatic vehicle classification (AVC) data has been collected from 3 different major highways (4-lane, 6-lane, and 8-lane highways respectively) in the Greater Seoul Area (GSA) for 2 months (August and September 2011), and it provides a venue on which real world data-based HV and PCE related analyses can be conducted. Typically, the HVs are converted into PCEs by considering road slopes, road length, geographical characteristics and the ratio of HVs to other vehicles. Even if all other factors remain intact, the influence of the ratio of HVs can be dependent on the traffic flow rate, [vehicles/lane/hour]. This paper examines the effect of HVs on traffic flows with the real-world AVC data of the GSA by analyzing the relationship between the average speed, HV ratio, flow rate, and number of lanes. It is found that the average speed generally decreases as the flow rate and HV ratio increase for the 6-lane and the 8-lane highways as expected. For the 4-lane highway, the speed decreases as the flow rate increases as expected but the speed interestingly stabilizes when the HV ratio is between 25 – 45% and even recovers after HV ratio exceeds 45%, which implies the need of reexamining existing methods of deriving HV factors for highway capacity manuals..

This paper was sponsored by TRB committee AHB40 Highway Capacity and Quality of Service.

01550057

15-0874

English

18p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; References; Tables

Automatic vehicle classification; Estimating; Heavy vehicles; Highway capacity; Passenger car equivalence; Traffic flow; Traffic speed

Seoul (Korea)

Data and Information Technology; Highways; Operations and Traffic Management; I72: Traffic and Transport Planning; I73: Traffic Control

Transportation Research Board Annual Meeting 2015 Paper #15-0874

TRIS, TRB, ATRI

Dec 30 2014 12:23PM