ABSTRACT
There has been a constant theme throughout the preceding chapters that the transport system should be treated as an entity, including all modes and the interfaces between them. The logic behind this stance is that the great majority of movements consist of a number of linked segments, often by differing modes, stretching from the journey start to its end and including the interfaces between segments. This system unity implies that investment should be from a single transport budget rather than individual modal budgets, and this, in turn, implies that there has to be a single assessment methodology. Chapter 19 described the development of the current methodology, but it is inherently weak, failing to reflect the need for interchange and making it impossible to mime inter-modal travel choices. Furthermore, the existing methodology focuses upon specific, often high-profile, modal projects such as the Edinburgh Tram, the London–Midlands high-speed railway and the third runway at Heathrow Airport, all projects which are restricted to providing just one segment within inter-modal journeys and which therefore rely on other modes to support them. This focus upon specific modal projects prevents the identification of the best deployment of a given budget over possible mixtures of other, perhaps smaller, but mutually supportive, projects. For example, the £600 million spent on the Edinburgh Tram may have been better spent on a range of improvements to the city’s public transport, but there was no methodology to assess possible alternative bundles of actions. Exactly the same problem besets the investment of £34 billion in the London–Midlands high-speed rail proposal, an investment which will require improvements to the ancillary access modes with each supporting project having to be separately assessed. The existing methodology as described in WebTAG is designed to assess whether or not the investment in one project is likely to reach a threshold rate of return.
