Sinclair Knight Merz were commissioned by BAA to undertake a major updating and upgrading exercise of their existing Heathrow Surface Access Model (HSAM). The existing model was created to develop demand forecasts for the Heathrow Express scheme and to support the surface access strategy development for the Terminal 5 Public Inquiry.
With the experience of Heathrow Express in operation, there is now new independent information on the accuracy of the forecasts of air passenger modal split produced by HSAM, which suggests that further model refinement/development may be required. There are also a series of new issues for mode split modelling which the upgraded model needs to be able to address:
- The mix of rail services to LHR may change substantially in response to both Crossrail and BAA plans, including potentially slow and fast, dedicated and non-dedicated services; and
- there is an emerging strategy for road user charging in London and at the London airports and the model will be needed to help develop these strategies.
The broad aim of this work is for BAA to have available models capable of estimating the impacts on surface access mode shares of
- airport and transport infrastructure provision;
- other BAA and government policies; and
- general scenario effects.
The study was followed up by the development and testing of a coach strategy for Heathrow and the setting-up of a similar mode split model for Gatwick.