Microscopic Modeling of Traffic Within Freeway Lanes

Bunker, Jonathan M. & Troutbeck, Rodney J. (1995) Microscopic Modeling of Traffic Within Freeway Lanes. Transportation Research Record, pp. 19-25.


Microscopic models provide an understanding of traffic operations at the level of passage of individual vehicles. Roadway performance can be ascertained by understanding how vehicles interact with each other. Cowan's M3 headway distribution models were calibrated for the curb and median lanes of two-lane mainline freeway segments, using data captured at 14 sites. Calibration of the relationship among Cowamn's M3 parameters, proportion of headways greater than a minimum of 1 sec, and flow rate yielded exponential decay equations for each lane. The M3 models provide a source of vehicle arrivals for gap acceptance models, which may be used to quantify the ability of drivers to change lanes, for example. It was found that the parameters calibrated for each lane are suitable for use at any mainline site, independent of site-specific conditions. The proportion of small headways was found to be higher in the median lane than the curb, for all flow rates, and for both lanes lower than their respective equivalents on arterial roads with intersections. The largest bunched headway was considered to be between 2 and 3 sec. The models predicted bunching between 85 and 93 percent of median lane vehicles, and between 75 and 90 percent of curb lane vehicles, at capacity. The lesser amount of curb lane bunching reflects its use as a slower vehicle lane with greater stream friction.

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ID Code: 10873
Item Type: Journal Article
Refereed: Yes
Additional URLs:
Keywords: traffic flow, traffic engineering, freeway, headway distribution, gap acceptance, headway, traffic bunching
ISSN: 0361-1981
Subjects: Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > CIVIL ENGINEERING (090500) > Transport Engineering (090507)
Divisions: Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Copyright Owner: Copyright 1995 Transportation Research Board (US)
Deposited On: 22 Nov 2007 00:00
Last Modified: 15 Jan 2009 07:55

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