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 used to estimate the benefits of reducing congestion in the absence of a multi-modal model.
The previous version of this guidance was published in November 2021.
TAG provides information on the role of transport modelling and appraisal, and how the transport appraisal process supports the development of investment decisions to support a business case.
