Group 2: Kathryn Berger, Jenna Bilsback, Anna Guidi, Stephen Mais, Annie Raftery, Darryl Michaud
Underpasses and Bridges
Both underpasses and bridges are useful to separate different forms of transportation. They provide a safe opportunity for pedestrians and bicycles to move uninterrupted, away from vehicular traffic. The drawbacks of incorporating these two features in a city plan is that they can be pricy, visually unappealing, and underutilized if they have too steep a gradient.
We analyzed the following three tunnels and bridges in Delft:
A1: Abstwoudsebrug
The bridge is 10.5 meters long, crossing over a narrow portion of the canal. The Abstwoudsebrug is 1.5 meters wide and can comfortably fit three bicyclists, and has space for more depending on the wobble of the riders. There is a wide pedestrian path on one side of the bridge and a narrow (barely can fit 1 person) on the other. Having the sidewalk only on one side creates traffic stress for pedestrians who have to cross over the busy bike path. The arc of the bridge is fairly steep. A higher arced bridge incorporates more materials, increasing the price of structure.
It provides a convenient connection between much of the student housing at TU Delft and the academic buildings. As a result, the bridge is very heavily utilized as there are 15,000 students that attend the university, most of whom cross over the bridge daily.
The bridge is not conveniently accessible by through car traffic. Cars that pass over the bridge have to turn to access a main road, and are blocked by the Abstwoudsetunnel from going directly to a main road. If the bridge was not there, bicyclists would have to ride out to the main road, adding 2.5 km onto their trip.
A2: Abstwoudsetunnel
The Abstowoudsetunnel has a similar function to the Abstwoudsebrug as it creates a region of connectivity from student housing to academic buildings. The tunnel and the surrounding area is currently undergoing some major reconstruction. Originally the tunnel ran under the train tracks. Now, it runs over the train, which was recently installed underground. In the future, the tunnel will be below large office and commercial buildings.
The underpass has a fairly slight angle from one direction, which allows it to be comfortable for both walkers and cyclists. However, on the other end of the tunnel, the side close to the university, has two sets of stairs. For bikers, this is a huge inconvenience because it is necessary to demount, and carry your bike up or down depending on your direction. Going toward the university there are two flights of stairs adjacent to one another, that lead into a single flight up another stretch. This creates a bottle neck affect because each of these sets has a very small rail that your bike can track on so bike travelers go from 2 rails to 1. The large gradient of the stairs make it extremely difficult to manage, even with the bike track. During rush hour, it will be necessary for some bikers to carry their bikes up the stairs, in order to keep traffic flowing.
The stairs are a large enough annoyance that I am sure a lot of cyclists take alternate routes in order to avoid demounting, and carrying their bike on the stairs. For the average biker, it would add approximately 4 minutes to the journey, in order to avoid this route.
The bike program should pay to make some alterations to this route because it is an extremely direct way for students to travel. The route is no longer to avoid railway traffic, so it should be charged to the bike program budget. It would be a good idea to extend the tunnel, taking out the stairs and making a ramp. The tunnel should be extended long enough to avoid the busy road that you must pass directly after exiting, in order to increase the flow of traffic and safety.
A3: Hoventunnel
The Hoventunnel stretches beneath a very busy 4 lane highway. It provides pedestrians and cyclists and safe alternative to crossing the main street. It would not be comfortable to cross the road above, and it would cause a backup since there is so much traffic. The entrance of the tunnel is quite small making it difficult to find initially. It was on the left side of the road of the photo included below. If you are not looking for it, it is very easy to miss.
Upon entry you can see the other end of the tunnel. This is a nice feature because people can be easily seen, making passing through a comfortable experience. One aspect we noticed was a build up of water on the tunnel floor. The upkeep and improvements should be a cost for the highway department, since they do not have space for non-motorized people to cross effectively or efficiently.
