Modelling Impacts of Cycling in Highway Network Models
Serbjeet Kohli, Steer Davies Gleave, Alisagar Inayathusien, Transport For London, Tom Caulfield, Steer Davies Gleave
This paper summarises the work carried out in a recently completed study by Transport for London (TfL) to assess the impacts of projected cycle demand growth and associated infrastructure investment on other highway users.
The Mayor of London has set out a target, in the Mayor’s Transport Strategy, that cycle mode share in London would increase to 5% by 2026. This increase would be equivalent to a 400% growth in cycling trips in comparison with 2001 levels of cycling. To enable the achievement of these targets a significant investment is planned to take place to enhance the existing cycling infrastructure and to deliver new cycling infrastructure which can support this growth.
For strategic modelling purposes the volume of cyclists is generally considered to be insignificant to have an impact on the overall model forecasts. Therefore cycling is often ignored in traditional transport modelling applications. A number of demand models exists which consider cycling as part of the total demand estimation stages however representation of cyclist as an explicit mode in assignments is rare.
However in several major cities across the world cycling is increasingly becoming a mode of choice. Particularly for short distance movements in dense urban centres, as those found across Europe, cycling is rapidly becoming a significant mode. This recent change has meant that both transport planners and modellers can no longer ignore cycling in assessment of various projects and schemes being planned for the near or distant future.
This paper summarises the work carried out in a recently completed study by Transport for London (TfL) to assess the impacts of projected cycle demand growth and associated infrastructure investment on other highway users. The study focused on the Central London Activity Zone, and the assessment was using TfL’s SATURN-based Central London Highway Assignment Model (CLoHAM). The existing model structure was used, with an additional stage of cycling route choice, the results of which were then used in the car assignment as background flows. This multiple-stage assignment concept was calibrated against observed cycle flows.
In this paper we highlight the various technical issues that were faced when trying to upgrade a traditional highway assignment model to represent cycling as part of a regular highway assignment process. We present the approach that was taken to create the modelling tool which was used for cycling infrastructure and demand impact assessments required from this study. We also look at areas which need further consideration such as PCU values at different infrastructure types and different junctions.
Association for European Transport