In a novel comparison, one of our BSc students used sustainable design of skyscrapers to rethink how bicycle tunnels in the Netherlands are constructed. Not only could this approach save money, but it can also determine how to save materials, use less concrete and thereby less emissions, or compare alternative materials. Different shapes of tunnels could allow for different weight distribution depending on the material types. You may assume this is already done automatically, and for standard designs this may be the case. However, for this case a partially open tunnel underneath a roundabout was designed, which is more common in a country like the Netherlands. Having an open roof changes the distribution of forces from a standard design. The link to the full thesis in the repository is here and the abstract can be found below.
Abstract
More and more bike tunnels are being developed in the Netherlands due to the rise in population numbers. Bike tunnels often provide safe road crossing for pedestrians and cyclists, promoting uninterrupted traffic flow. However, conventional bike tunnel designs are expensive and carbon-intensive due to the extensive use of overly designed concrete structures. Meanwhile, in the tall buildings sectors, many structural and sustainable innovations have been made. These innovations led to many modern buildings being created that are material efficient and climate resilient.
This research project started by investigating some of the most representative structural and sustainable developments in the recent decades. The follow-up of the investigation resulted in the creation of two structural design prototypes, specifically developed for a bike tunnel project in the Municipality of Ommen. The first prototype implements a topology optimization to structural members. The second prototype deploys a multi-functional centred V-brace system. Both of these prototypes had in focus two sustainable design elements: a composed concrete-timber floor and an open-air design. With the use of Dynamo, a parametric design automation program, the designs were modelled in Revit and transferred to Robot Structural Analysis for structural verification. While the first prototype is structurally not feasible, the second prototype successfully passes the Eurocode verification.
By using IBIS voor Infra and DuboCalc, prototype two is further evaluated for material costs and environmental impact. The evaluation returns a promising cost efficiency result and a significant reduction in environmental impact. The implementation of this type of multi-functional structural systems could sufficiently reduce structural material usage, when compared to conventional single-purposed structural systems. The results also suggest a 1+1>2 relationship between structural and sustainable optimization. While the first prototype is unfeasible, its modelling process sheds some light on how topology optimization could be realistically applied in practice.
Overall, this research project is proposing a promising structural system solution for future bike tunnels. At the same time, it provides insights on how project costs and environmental impact can be reduced by using parametric modelling automation during the design phase, and topology optimization in the manufacturing phase. This proposed approach can prove useful to future projects, and can further enrich the industry.
