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Mobility and Transport

Overview

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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Population

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

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Accessibility

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 http://ec.europa.eu/transport/node/6167{Challenges that cities face and how cycling can address them as Link}

In-depth measure analysis, case studies and further guidance

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Key features

Grade-separated crossings offer people who cycle a route across barriers such as rivers, busy roads, and railway lines. The crossing may be raised above or lowered below the level of the barrier and the two main types are cycle bridges and cycle tunnels. The advantages and disadvantages of each are summarised in the table below, which is taken from the PRESTO grade-separated crossing factsheet and adapted from CROW 2006, Design Manual for Bicycle Traffic:

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Function and objectives

The crossings provide an alternative route across a barrier that is safer and more direct for people who cycle. As cities grow and populations increase, roads are likely to get busier, which will create more barriers to cycling around a city. Grade-separated crossings are therefore an important solution to these changes which would otherwise reduce the cyclability of cities.

  • More direct – Rivers and railway lines can present barriers to mobility around cities, and so opportunities to cross these will increase accessibility and the directness of journeys.
  • Increased Safety – Busy or high-speed roads present a significant safety risk to cyclists attempting to cross.
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Cycle bridge in the Capital Region of Denmark,Supershighways The Capital Region

Range of alternatives

While there are no suitable alternatives for crossing rivers and railway lines, other cycling measures could be considered when crossing busy roads. Soft infrastructure measures at the level of the barrier, such as advanced stop lines, cycle lanes and other traffic restrictions giving people who cycle priority can contribute to increased safety for cyclists at crossings. Hard infrastructure measures such as signalised junctions and roundabouts can also be considered. The figure below provides an overview of types of road crossings and when they are appropriate. The figure is taken from the Sustrans Design Manual - Handbook for cycle-friendly design.

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Notes

1.Table provides guidance on appropriate crossing type, but individual locations should be assessed on a case-by-case basis.

2. Main cycle routes justify a higher level of service than other routes and so are likely to have greater priority at crossings and junctions.

Links with other measures

Grade-separated crossings often form part of regional and urban cycle networks (Copenhagen, Focus on Cycling), allowing continuous cycle routes that have reduced contact with other transport modes and are more direct. Cycle lanes are often used by lots of people cycling, so it is important to minimise the number of stops and contact with traffic. As highlighted by the cycle bridge in the City of Bregenz, connecting grade-separated crossings with existing cycling infrastructure contributes to the success of the measure.

Performance

Accessibility

Removing the physical barriers to cycling mobility will reduce the distances that cycling people have to travel and increase accessibility. Options to cross rivers and rail lines are not always frequent, and while it is easier to travel longer distances in motor vehicles, it can be a significant deterrent to cycling if the journey distance is increased because of a barrier. The CROW manual highlights ‘directness’ as a key requirement for a bicycle network [3]. Cycle bridges and tunnels are an effective way of reducing the detour factor of a journey.

The ‘De Snelbinder’ cycle bridge in Nijmegen is a very good example of how the measure can be used to successfully target a specific area or group of people that have reduced access within a city. Every day, 5,000 people use the route to travel between the northern part of the city and several important destinations, including the city centre, the university campus and train station. As a result, it has brought local communities together and public opinion is very positive.

Congestion

By increasing the efficiency and attractiveness of city cycle networks, this measure can contribute towards encouraging more motor vehicle drivers to switch to a bicycle. The Rijn Waal Pad is an efficient cycle network that expands outside of the city centre. It is used by many commuters, resulting in fewer vehicles on the roads during peak times.

This measure may also increase the efficiency of traffic flow by taking people who cycle away from busy roads. This is the case in Bregenz, where a new cycling tunnel allows people cycling to avoid a busy road.

Road safety

The vast majority of cycling accidents involve road traffic, and over two-thirds of reported cycling accidents happen at or near a road junction [4]. By removing the exposure of people who cycle to road traffic at crossings, safety will be increased.

Parameters of success or failure

This measure is generally applicable to any city where a barrier or busy road is hindering the accessibility of people who cycle.

As demonstrated in the Bregenz case study, the financial feasibility of the measure may rely on the ability to adapt a cycling bridge or tunnel, rather than build a new one. It may be necessary to seek support through national funding or sponsorship (Bregenz).

The scale of the projects means that early and effective communication with relevant authorities and stakeholders is important, as demonstrated by the Bregenz cycle bridge.

The use of tunnels by cycling people will decrease if people feel unsafe and so the design of the tunnel must include adequate lighting, sufficient space and shallow gradients. Lighting is especially important if the user cannot see all the way through to the other side. In the Eisenhower tunnel, which is part of the RijnWaalpad, there are three windows in the roof, allowing daylight to illuminate parts of the tunnel. The image below shows lighting in one of the tunnels along the Farum Route of the Cycle Superhighway in the Capital Region of Denmark. According to users, the lighting increased the feeling of safety. Depending on the volume of bicycle traffic, different widths and degrees of separation should be considered (London Cycling Design Standards).

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Tunnel lighting on the Farum route, SuperhighwaysThe Capital Region

Finally, demonstrating that the structures will contribute to improved access generally (e.g. pedestrians and people with reduced mobility) will contribute to the business plan. Since the structures are costly and require people who cycle to deal with gradients, a strong business case is often required.

Key lessons for transferability

In each case study presented on this page, the success of the grade-separated crossing was supported by its connection with existing cycling infrastructure, or the construction of complementary cycle infrastructure.

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[collapsed title=Infrastructure quality design guidance – Grade-separated crossing]

Overall recommendations

  • Steep slopes should be avoided and ideally, people who cycle should be able to keep riding on ground level.
    • Across natural barriers, ramps onto and off the crossing should have shallow gradients.
    • Across carriageways, it may be possible to raise (for a tunnel) or lower (for a bridge) the level of the carriageway, allowing the crossing to stay at the same level.
  • Use appropriate dimensions that consider the comfort of the user by providing enough space.
    • Tunnels should have sufficient headroom. PRESTO recommends a minimum height of 2.5m (PRESTO, Grade Separation, 2012).
    • Cycle paths of both crossing types should be sufficiently wide.
  • Tunnels can make people who cycle feel unsafe and so there are a number of design principles that can increase attractiveness:
    • Ensure the approaches to tunnels are open and unobstructed
    • Ideally, the exit of the tunnel should always be visible although this is not always possible if the tunnel needs to bend.
  • Lighting is very important, and this should be provided by adequate artificial lighting and gaps or windows in the tunnel roof allowing daylight to enter the tunnel. In one of the tunnels on the Rijn Waal Pad, there are coloured lights that can be changed by users via an app.
  • Bridges should also be well-lit.
  • Handrails or other barriers should be provided on bridges and a covering may be considered to provide protection from the weather.

City considerations

  • Adjusting the level of the carriageway to maximise the comfort for people who cycle is an expensive and complex activity. Therefore, the resources available and the expected level of cycling will influence whether it is appropriate. Furthermore, it is unlikely that engineering works of this level can be justified by the needs of people who cycle and so the solution should provide benefits for pedestrians and possibly public transport.
  • If space is not available for a ramp with a shallow gradient, stairs with a bicycle channel should be considered. Lifts or escalators can support this solution and improve accessibility.

City practitioners should consult national cycle infrastructure design standards or regulations (where available) regarding the appropriate implementation of cycle highways in respective Member States (including cycle track, materials, signage etc.).

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[collapsed title=Case studies]

[collapsed title='De Snelbinder' - Cycle bridge (Nijmegen, NL)]

  • Location: North, North West
  • Population: 175,000
  • Cycling Modal Share: 30%

In 2004, a cycling bridge was constructed in Nijmegen to provide a connection between a new housing development and the city. It connects the northern part of the city with many important destinations including the city centre, the university campus and central station.

Design features and considerations

The bridge was added to an existing railway bridge and was more expensive than budgeted. It has a total length of 2 km with a main span of 235 m.

Due to the high costs associated with implementing a cycle bridge, it is likely that national funding (large budgets) would be required. Furthermore, cooperation with other key stakeholders may be necessary, such as a railway company.

Impacts

5,000 cyclists use the bridge every day and it is expected that this will double. Public opinion was very positive as the cycling bridge removed an existing barrier. It also brought local communities together, in particular houses that were starting to feel cut off from the city.

The bridge is architecturally beautiful with a good view of the city. This makes the bridge attractive for other users of the bridge (e.g. joggers).

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[collapsed title=Rijn Waal Pad – bridges and tunnels (Nijmegen, NL)]

  • Location: North, North West
  • Population: 175,000
  • Cycling Modal Share: 30%

In Nijmegen, a fast cycling route (Rijn Waal Pad) has been developed as part of a network to increase regional connectivity. Where there are rivers and railways, under- and overpasses have been built. The figure below shows the Bike tunnel under the N325 along the RijnWaalPad.

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Eisenhower tunnel along the RijnWaalpad, Nijmegen

Design features and considerations:

  • Important to ensure that slopes are not too steep
  • Good lighting should be provided. In one of the tunnels, there are coloured lights that can be changed by users via an app.

The cycle route cost approximately €1 million per km, which includes any tunnels or bridges. (Total €17 million for 16 km route)

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[collapsed title=Cycling tunnel and bridge (Bregenz, AT)]

  • Location: North, North West
  • Population: 29,562
  • Cycling Modal Share: 20%

In Bregenz, a cycling tunnel and a cycling bridge have been constructed to remove geographical barriers and improve the cycling network. As well as providing safer and more convenient cycle routes, they are adding to the public profile of cycling and walking and have been positively received by the citizens.

Cycle tunnel

The 200 m tunnel makes use of a former railway connection that has been reopened for people who cycle and pedestrians, providing a safer, quicker and more convenient route. In particular, the tunnel connects the two city districts of Feldmoos and Vorkloste and provides people who cycle with an alternative to a busy road with a steep slope.

The tunnel cost €300,000 to adapt and the project was partly financed by sponsors. The ability to adapt an existing tunnel was important for the feasibility of the project as it would have been much more expensive to construct a new tunnel.

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Tunnel Sandgrubenweg Riedergasse, Bregenz

While no data has been collected, the use of the tunnel is much higher than expected for both people who cycle and pedestrians. The tunnel has been designed with bright lighting and visibility of both ends at all times, which has contributed to its popularity.

The transferability of this measure may be limited to the opportunity to adapt an existing tunnel, as constructing a new tunnel can be expensive. It is important to ensure good interior design of the tunnel so that people feel safe and comfortable. A key challenge to address when creating tunnels or underpasses is that people may feel unsafe.

Cycle bridge

The western edge of the city of Bregenz and the municipality of Hard are separated by the river Bregenz Ach. The cycling bridge was constructed to offer a route over the river and both municipalities took responsibility to connect the bridge to their existing cycling infrastructure, creating a continuous network. Including the bridge, the project created a 700 m long cycling track with a width of 4-5 m.

The quality of connection that the bridge provides through its location and link with existing cycle infrastructure, contributes significantly to its popularity. It was also important to have good collaboration with the relevant environmental authorities and the neighbouring municipality. Both sides of the bridge are near a Natura 2000 area and so it was important to begin cooperation with the respective nature protection authorities and water management authorities as early as possible, and maintaining the cooperation throughout the planning process.

The bridge cost €3.1 million.

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[collapsed title=Key guidance, further reading and references]

PRESTO / Rupprecht (2012) “Grade Separation"

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The Sustrans Handbook for cycle-friendly design (page 26-29)

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(8.34 MB - PDF)
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London Cycling Design Standards, 2016 (chapter 7, page 23)

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(1.33 MB - PDF)
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Transport for London’s ‘International Cycling Infrastructure Best Practice Study’

tfl-international_cycling_infrastructure_best_practice_study
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(5.08 MB - PDF)
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CROW (2017) Design manual for bicycle traffic. Chapter 6

The Sustrans Design Manual ‘Principles and processes for cycle-friendly design’, Chapter 8

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(2.28 MB - PDF)
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Mobile 2020 ‘More biking in small and medium sized towns of Central and Eastern Europe by 2020’ handbook on cycling inclusive planning and promotion, pages 106 on cycle bridges and tunnels

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Copenhagen’s guidelines for the design of road cycling projects - Focus on Cycling

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(17.53 MB - PDF)
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Footnotes

[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

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[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

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