Research and analysis

How additional road capacity affects travel demand

Explores the relationship between additional road capacity and travel demand, and the implications for transport appraisal.

• From: Department for Transport
• Published: 28 May 2026

Documents

The impact of induced demand on benefits: a think piece

PDF, 1.82 MB, 91 pages

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Details

This research assesses how additional road capacity affects travel demand and how induced demand alters:

• traffic forecasts
• appraisal
• value for money

It also explores whether, when and why new capacity generates extra travel, and the implications for benefits, costs and decision making.

Phil Goodwin completed this research on behalf of the Department for Transport (DfT).

Published 28 May 2026