Forecasting the Economic Impacts of the Oxford to Cambridge Expressway
John Swanson, Steer Davies Gleave, Jake Cartmell, Steer Davies Gleave
Describes how a land-use model was used to forecast the employment impacts of the proposed Oxford to Cambridge Expressway; presents headline results; comments on the three-level approach to appraisal recently proposed by DfT.
This paper describes work done to forecast and appraise the impacts of the proposed Oxford to Cambridge Expressway. While much of the work was fairly conventional (‘Level 1’, in DfT’s recent draft guidelines), the paper will focus mainly on the Level 3 appraisal work; this is where the effects of land use changes are taken into account and their impacts on the economy, particularly on employment, are quantified.
The corridor runs in an arc from Oxford, through Milton Keynes to Cambridge, encompassing a network of economically and academically important places where much innovative and high value activity takes place. However, the transport links along the arc are not good, either by road or rail. This is what the study was set up to address.
The initial phases of scoping and economic profiling of the corridor will be outlined briefly, and the proposed schemes (which include East-West rail) will be indicated. The focus of the paper however will be on the application of a land use model to quantify the employment impacts. This model was an implementation of Steer Davies Gleave’s Urban Dynamic Model (UDM), specifically UDM-Lite, a simplified version of the original model. The project schedule required this to be built and delivering results in under three months, a target that was met. One reason for this success was the way we used existing data sources to prime the model. Base year highways times were derived from the Pitney Bowes Speed Profile data, which is sourced from TomTom, while the rail model MOIRA was used to build base year rail generalised times and costs. Baseline assumptions about background economic growth and expected changes in land use were derived from an analysis of planning documents from 13 local authorities along the corridor, coupled with NTEM population and employment projections.
The model was initialised so that it could replicate the future economic scenarios envisaged in NTEM and the local planning documents in the absence of investment in the Expressway. With that position set up, the model was then used to test the marginal impacts of the Expressway schemes. Highways England’s South East Regional Transport Model (SERTM) was used to provide the incremental changes in drive times caused by the Expressway, while earlier modelling for East-West rail was used to provide incremental changes in rail times.
The model showed that the Expressway would generate an increase in employment in the Local Authority Districts along the corridor of up to about 1.6%, depending on location, with some abstraction from London and the rest of the UK. This happens because of the improved patterns of connectivity between employers and their workforce, and employers and their markets and suppliers. While this change may appear modest, the GVA value of these jobs was significant and made greater still because of a clear shift in future years towards high value employment such as advanced manufacturing and knowledge service industries. There was also some increase in the local workforce, attracted by the improved employment opportunities.
The paper will present the headline results and reflect on how the work sits within the three level framework for appraisal that DfT has recently published.
Association for European Transport