A bicycle underpass is a well established possibility to build grade-separated crossings for pedestrians and cyclist to cross tram tracks or major roads. It is not only safer but also ensures a significant higher operation capacity for the major infrastructure line as well as for the people crossing. Compared to the other main option a bridge, the underpass has two crucial advantages. Firstly it can be constructed with less height difference between the two grades, because the path with lower minimum height requirement is the bottom part. The second crucial advantage is that cyclist can use the momentum gained while riding downhill to ascend on the other side, compared to a bridge where they need to climb without momentum and then need to brake on the descent.
Image 1 exemplary bicycle underpass with angeled concrete side panels [1]
The design of an underpass is influenced by the available space and the dimensions of the track crossed. Nevertheless materials often used are concrete or reinforced concrete elements for the sidewalls and ceiling as seen in the picture. Also common is a typical sewer system to ensure no puddle at the lowest point. In contrast the material used for the road surface of the underpass differs. Often the typical surface for cycle path and pavements at the building location is also used for the underpass e.g. red asphalt in the Netherlands, tiles in Germany or concrete in some instances. An exception is that for gravel or earth paths the surface in the underpass is usually still asphalt, tiles or concrete. Therefore these three design options are examined in this project and how they influence maintenance planning and lifecycle costs. Two sentences conclusion. It is important to note that in the comparison in this project the user satisfaction with the surface is not internalized and in reality the option with higher LCC could be implemented due to a more pleasant ride. Policy decisions are not based entirely on factors that can be easily added to a model.
[1] https://commons.wikimedia.org/wiki/File:Eisenhower_Tunnel_.jpg