The city of Haarlem wanted to create a barrier free passage where a main arterial route for motor traffic and a main cycle route along a river bank crossed each other’s paths. But there was no space for an overpass, and a tunnel right next to a river was not such a great idea either. So designers came up with the plan to lead the cycle route through the river under the approach span of the two existing drawbridges for the arterial road. A perfect idea, but there was just one small problem: there was not enough clearance, the bridges were almost 30 centimetres or a little under a foot too low. So what do you do? That was not so hard in a country full of civil engineers who specialize in dams, dikes and flood gates: you simply lower the cycle route below the water level so that there is enough head room for the people cycling there.
The designers also faced some other challenges in building this bridge/underpass under the existing Buitenrustbruggen. One house boat had to be removed and there was a lot of paperwork involved because of the “building in open water”. The main difficulty was building a structure that wouldn’t start to float in the fluctuating water level of the river ’t Spaarne. That is why the cycle path was built in a steel waterproof “box” with a height of just 50 centimetres, that is kept in its place with sufficient weight. The river water level can rise and fall without the box moving. The gutter and the rain water drainage are hidden in the box, all you see is a row of holes. Two pumps take care of keeping the surface of the cycle path – below the water level of the river – rain water free and dry. A final and important challenge was making this underpass so attractive that people on their bicycles would want to use it. The designers tackled all these challenges very successfully.
The design was by IPV Delft creative engineers. I have shown you other examples of their work before. Most notably the Hovenring in Eindhoven and a cycle bridge in Enschede. What all three have in common is the way the lights are fitted in the railings. The design of the Haarlem bridge/underpass was formalised in August 2009. The structure was opened to the public late June 2011.
The cost for this innovative bridge/underpass was 2.31 million Euros, paid for by the province of North-Holland (80%) and the city of Haarlem (20%). The steel bridge is 110 metres long, 6.5 metres wide and the steel alone weighs over 200 metric tons. It was shipped to Haarlem from the factory in Amsterdam in one piece. The extra weight to keep it in place was only added on the final position, which sank the bridge in position on the previously constructed foundation under water to which it was firmly connected.
In the video you can see that it is heavily used by all types of people cycling on a variety of bicycles. The city of Haarlem can be proud to have created one more barrier free cycle route in the Netherlands. And cycling under the water level on a cycle ‘bridge’ is a unique experience, even in the Netherlands.
Video showing the semi-submerged Haarlem bicycle bridge