Mobility and Transport

Clean transport, Urban transport

1.4 Grade-separated crossings

1.4 Grade-separated crossings


Grade-separated crossings (GSCs), such as tunnels [1] and bridges, provide people who cycle with safe and efficient ways of crossing natural and artificial barriers. They may be a new piece of infrastructure or an upgrade to an existing piece of infrastructure. Often, they will be designed to cater for pedestrians as well.

Considerations for applicability 

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Level of cycling

Due to the costliness of these crossings, the number of expected people on bicycles potentially using the crossing is an important determinant of whether such a crossing is suitable. The crossing should be able to adapt to increased use.

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Urban layout/topography

Grade-separated crossings for cyclists should be considered when attempting to address physical obstructions, such as rivers, railway lines, and stretches of the major road network. 

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A crossing could improve access to city attractions or commercial areas, encouraging tourists to cycle. A grade-separated crossing could improve access to educational facilities and places of employment, reducing physical obstructions and encouraging local populations to cycle.

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Finance resources

The initial capital required can be significant, depending on whether the crossing is new or an upgrade to an existing crossing. Finance is required for ongoing maintenance.

In the UK’s Cycle City Ambition (CCA) initiative, new bridges have cost €1.2 million to €5.6 million and two upgraded bridges cost €0.1 million and €0.6 million [2]. The Bregenz cycling tunnel cost €300,000 to adapt.

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Time & human resources

Multiple planning, engineering and construction personnel will be needed. The number of personnel and the time required can be significant but will depend on the scale of the construction and whether the crossing is new or an upgrade. Personnel and time are required for ongoing maintenance.

Measure impact highlight

3 way arrow representing accessibilityAccessibility

Grade-separated crossings can significantly increase accessibility by offering a safe and direct route across barriers such as rivers, railway lines or busy roads. This will often result in the reduction of a cycling route’s detour factor, which is an effective way to increase the attractiveness of a cycle route. 

Note: An overview of the direct and indirect impacts resulting from correctly implemented cycling measures is available in Challenges that cities face and how cycling can address them

In-depth measure analysis, case studies and further guidance


[1] Also referred to as subways or underpasses

[2] Taylor I and Hiblin B (2017), Typical Costs of Cycling Interventions: Interim analysis of Cycle City Ambition schemes PDF icon typical_costs_of_cycling_interventions_interim_analysis_of_cycle_city_ambition_scheme

[3] A way of measuring directness is the detour factor, which is the distance between two points on the network, divided by the straight-line distance. As a guide, the detour factor should not exceed 1.4 and to make cycling attractive over short distances, the detour factor of the cycle network should be less than the detour factor for cars. CROW cites a detour factor of 1.1 as an aspiration.

[4] The Royal Society for the Prevention of Accidents, Road Safety Factsheet, November 2017 PDF icon rospa_cycling-accidents-factsheet