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To ask the Secretary of State for Transport what weight she gives to the likely effect on (a) car journeys and congestion, (b) value added tax receipts, (c) fuel duty receipts, (d) carbon emissions, (e) air pollution and (f) reliability of journey times when assessing the costs and benefits of a light rail scheme.
The Department uses a framework called the New Approach to Appraisal (NATA) to undertake cost-benefit analysis of schemes relating to all transport modes including light rail. The Department aims to consider all impacts of transport schemes, including those listed, when undertaking cost-benefit analysis. No definitive set of weights are applied within this framework, with the contribution of each of these factors varying according to the specific circumstances of the scheme. For example, the significance of congestion relief to the assessment of schemes in areas experiencing high delays will tend to be greater than schemes in areas experiencing few delays.
To ensure consistency across schemes, where possible, impacts are converted into monetary equivalents using a common set of values. This allows a variety of impacts to be aggregated and compared. In practise, the weight attached will depend on the size of impact that a scheme will have on each factor and the value attached to these impacts. Where available, standard values are used to value impacts, e.g. carbon emissions are valued at the standard cost of carbon issued by DEFRA.