Road pricing cuts traffic congestion, major Danish study confirms

A large-scale Danish trial with nearly 3,000 participants has demonstrated that road pricing “clearly reduces traffic” in congested areas, according to a new report by the Technical University of Denmark (DTU) and Sund & Bælt, published Tuesday.

The EU-funded study, conducted between November 2023 and July 2025, found that time- and location-based fees led to a 12–22% reduction in urban traffic and a 7–11% drop in suburban areas during peak periods. The largest effects were observed in Denmark’s four biggest cities—Copenhagen, Aarhus, Odense, and Aalborg—where congestion charges were roughly double during rush hours compared to off-peak times.

“The results unequivocally show that road pricing reduces traffic in the zones where it is introduced,” the report states. Ninette Pilegaard, DTU section head and lead researcher, noted that the trial confirmed expectations but also revealed the scale of the impact: “We see the greatest reductions in short trips within charged zones—trips that can more easily be replaced by cycling, walking, or public transport.”

The 44-week trial involved 2,900 volunteers who tracked their driving via a dedicated app, simulating payments from a virtual mobility budget. Fees ranged from DKK 0.50 to 3.25 per kilometer in outer zones and DKK 0.35 to 1.50 per minute in city and suburban areas during peak times. Survey data suggested some participants shifted to public transport or canceled non-essential trips.

The findings will inform a government-appointed expert group, tasked with recommending future car taxation policies by late 2026. While the report does not endorse a single model, Pilegaard emphasized that “the choice depends on political priorities”—whether the goal is maximizing congestion relief, revenue, or environmental benefits.

Denmark has previously debated road pricing, including a proposed 2012 congestion charge for Copenhagen that was never implemented. The new study provides the first localized evidence of its potential effectiveness in Danish cities.