Establishing the validity of cycle path capacity assumptions in the Highway Capacity Manual

Abstract

Cycle mode share increase is widely desired, but highway design practitioners lack the numerical tools to deliver infrastructure, instead relying on design standards and intuition, with little literature basis. As a case in point, the US Highway Capacity Manual (which is well-used internationally) has developed levels of service for cycle infrastructure which are, at their core, based on an assumption of non-interaction between multiple cyclists.

This paper uses a modified implementation of the Social Force Model to test the validity of this assumption. Necessary changes such as the consideration of acceleration characteristics and minimum maintainable speed are included. The resulting model produces valid outcomes in keeping with established traffic flow properties reflecting three-phase traffic flow theory and the ability for the stochastic elements in traffic flow to cause flow break
down.

The developed simulation indicates that there is a fundamental difference in outcome if cyclists are assumed to have a fixed-speed versus one they can change given their surroundings. This difference in outcomes is found to exist within the range of literature design flow capacities for bicycle infrastructure and also yields emergent outcomes which align closely with those known behaviours of highway vehicles which intuitively transfer to cyclists. These findings reinforce the standing need for large-scale empirical studies to determine the basic numerical and behavioural parameters for cyclists, upon which all design ultimately rests.

More information

Identifiers

ORCID for Ben Waterson: orcid.org/0000-0001-9817-7119

Catalogue record

Export record

Altmetrics