To make sure your tunnel can be safely and successfully adapted for trail use, obtain a certified report from a structural engineer describing the current condition of the tunnel. These will describe significant structural features of the tunnel that are not apparent from visual inspection. If possible, locate the tunnel’s original engineering drawings. If a corridor includes a tunnel, the first step is to determine its structural soundness. Tunnels are among the most striking physical features of a trail and are often the most memorable aspects of a trail experience, while underpasses offer safe crossings of roads or other barriers where an at-grade crossing would be dangerous. However, a tunnel or underpass on a trail can also present challenging structural, design and management issues. I will use the money to pay for travel costs and other expenses I have to make to create my articles and videos.Howard Tunnel on the York County Heritage Rail Trail - Photo CC Rob Carlson via Flickr If you would like to support my work for this site you could decide to donate any amount you can spare. And cycling under the water level on a cycle ‘bridge’ is a unique experience, even in the Netherlands. The city of Haarlem can be proud to have created one more barrier free cycle route in the Netherlands. In the video you can see that it is heavily used by all types of people cycling on a variety of bicycles. 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. It was shipped to Haarlem from the factory in Amsterdam in one piece. The steel bridge is 110 metres long, 6.5 metres wide and the steel alone weighs over 200 metric tons. 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 structure was opened to the public late June 2011. The design of the Haarlem bridge/underpass was formalised in August 2009. What all three have in common is the way the lights are fitted in the railings. Most notably the Hovenring in Eindhoven and a cycle bridge in Enschede. I have shown you other examples of their work before. The design was by IPV Delft creative engineers. ![]() The lowest point is almost 30 centimetres or a little less than a foot below the water level. A rendering of the bridge/underpass in Haarlem. The designers tackled all these challenges very successfully. ![]() A final and important challenge was making this underpass so attractive that people on their bicycles would want to use it. Two pumps take care of keeping the surface of the cycle path – below the water level of the river – rain water free and dry. The gutter and the rain water drainage are hidden in the box, all you see is a row of holes. The river water level can rise and fall without the box moving. 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 main difficulty was building a structure that wouldn’t start to float in the fluctuating water level of the river ’t Spaarne. ![]() One house boat had to be removed and there was a lot of paperwork involved because of the “building in open water”. The designers also faced some other challenges in building this bridge/underpass under the existing Buitenrustbruggen. A woman has just used the semi-submerged Haarlem cycle bridge. 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. 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 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. But there was no space for an overpass, and a tunnel right next to a river was not such a great idea either. 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.
0 Comments
Leave a Reply. |