Guidance

WebTAG: TAG unit A5-4 marginal external costs, December 2015

Information on the marginal external costs method in transport modelling and appraisal.

Document

Detail

Information on the marginal external costs method which is based on the change in various external costs such as congestion, air pollution, noise, infrastructure and accidents. The marginal external costs method is the used to estimate the benefits of reducing congestion in the absence of a multi-modal model.

This Transport Analysis Guidance (TAG) unit was updated in December 2015 to clarify the 3 sources of potential indirect tax impacts in rail appraisals. Further details of this change can be found in the forthcoming change document in unit A5.3 (PDF, 75KB).

The previous version of this unit was TAG unit A5-4 marginal external costs, January 2014.

WebTAG provides information on the role of transport modelling and appraisal, and how the transport appraisal process supports the development of investment decisions and business cases.