Today, we had an interesting lecture with Bertus Fortuijn, a Traffic Consultant and a Senior Lecturer at TU Delft. He talked about roundabouts for the whole morning, here are a few key things I took away from this lecture:
- Self enforcing/educating design is important to consider when designing roundabouts and traffic systems
- Statistically speaking, roundabouts are a lot safer for vehicles compared to four way intersections. However they are less safe for bicyclists.
- In order to make roundabouts safer for cyclists, there are three different methods a cyclist potentially use the roundabout: mixed traffic through the roundabout, bike lanes in the roundabout, or separate bike paths by the roundabout.
- The basic turbo roundabout design (arguably the most efficient design) can accommodate 3500 pcu/hr.
There were a lot of dimensions and figures in the 3 hour lecture, it was very technical and after a while, it became quite dry. What I enjoyed was the animations, so much better to see how these roundabouts work with vehicles in them!
We then biked down to a turbo roundabout which was about a 5 minute ride away from the uni. It was cool to actually see a real life turbo roundabout in action. The flow into it from the south was regulated by sensors and traffic lights. They do this to prevent an excess of vehicles into the roundabout. Specifically at this roundabout intersection, there were a significant amount of heavy trucks entering from the south, so it is easy to see why this would be regulated. Another interesting observation I made was that the lights were located a little bit away from the actual roundabout. Bertus Fortuijn in his lecture, had stated that this is done to make sure that vehicles still yield when entering the intersection because if they were to have the signals right at the intersection, once they turned green, the drivers may not think to yield to the traffic in the roundabout. The dutch have very precise traffic signal operations, always trying to minimize conflicts. I think it would be interesting to learn more about how their traffic signals are programmed. Below are a few pictures of the roundabout
