Date of Award

2011

Degree Type

Thesis

Degree Name

M.A.Sc.

Department

Civil and Environmental Engineering

First Advisor

Lee, Chris (Civil and Environmental Engineering)

Keywords

Civil engineering.

Rights

CC BY-NC-ND 4.0

Abstract

This study examines the effect of heavy vehicles (trucks) on entry capacity of roundabouts. The movements of vehicles were observed at 11 roundabouts in Vermont, Ontario and Wisconsin. Gap-acceptance parameters were estimated for cars and trucks separately; consistent with previous studies, it was found that critical headway and follow-up time were longer for trucks than cars. Follow-up times for truck-involved vehicle-following cases were found to be associated with central island diameter and entry angle. Gap-acceptance parameters for all entering vehicles were adjusted to a volume-weighted average of the gap-acceptance parameters for cars and trucks. Entry capacity was estimated using existing capacity models with the adjusted gap-acceptance parameters, and compared with the observed capacity at three roundabouts. The capacity models with adjusted gap-acceptance parameters estimated capacity more accurately than the models with unadjusted parameters. Microscopic traffic simulation model was also effective in representing truck characteristics and their impact on roundabout operation.

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