It is at least 30 years old, the cycle bridge over the A28, the motorway from Utrecht to Groningen. This part of that motorway was opened in 1985, but a 1983 picture shows the cycle bridge is already finished over the motorway under construction. It re-connects an old road (Bunnikseweg) that was cut in two by the new motorway, right at the municipal border between Utrecht and De Bilt. Today, the bridge makes it possible for people on a bicycle to cross 10 lanes of traffic of which 4 are slip roads. They are the access to and from the motorway for the Utrecht University area with the university hospital and the faculty buildings.
Just 700 metres to the west of the cycle bridge there is a cycle tunnel. That tunnel is in the shortest route from De Bilt to the Utrecht University area. It is part of the north-south high-speed cycle route to the east of Utrecht. (The red line on the map). That is where all the through cycle traffic goes, and that is also the reason why the bridge is relatively quiet. On weekends it must be busier on the bridge, because the route over the bridge is part of the so-called “Knooppunten Netwerk” (numbered junction network) a network of beautiful recreational routes. From junction 88 in the municipality of De Bilt to junction number 87 in Zeist, you pass the bridge via the green line on the map.
The bridge is clearly narrower than modern bridges that were more recently built. What makes the bridge special are the two circular ramps that give access to the actual bridge. The inclines become a lot longer with these spirals, a good thing because that decreases the gradient. The north-entrance has a gradient of 3.26%, the south-inline is only slightly less steep, 3.12% but as a cyclist you do not notice that difference. These figures are from a study that investigated the (artificial) inclines in cycle routes in the Netherlands.
Also from that study: the total length of the bridge is 400 metres and the highest point is at 6.47 metres. Pedestrians have stairs as an alternative access to the bridge. They do not have to use the much longer spiral ramps. But on the actual bridge pedestrians have to share the space with the people on bicycles. With the number of both these traffic users passing here, that is no problem at all.
The bridge serves as a clear example that even in the early 1980s, cycling infrastructure like this was built. A piece of infrastructure that must have been planned in the late 1970s. An era in which cycling was at an all time low in the Netherlands.
For some time it looked like the south spiral would disappear. The city of Utrecht planned a tram line from the centre to the University Hospital. The end of the line would exactly reach the place of the south spiral. The entrance to the bridge would then have to be replaced by a straight incline. The tram line was planned to end exactly there, so it could later be extended to Zeist, directly parallel to the motorway. But the plans have been altered to save money and the bridge will remain the way it is. That fortunately also means 45 old oaks along the country road to the south can stay.
Video showing the cycle bridge. Many of the people passing by on their bicycles seem to be recreational cyclists.