Published on 02 November 2020
Boerenverdriet drawbridge replacement and renovation contract
The Willemsoord area in Den Helder will be given a new boost, which will also change existing traffic routes. The development company Zeestad will be investigating options for putting the Boerenverdriet drawbridge, constructed by the Ministry of Defence in 1956, back into operation. Witteveen+Bos will be identifying the different options, including feasibility and costs, for achieving this aim.
The bridge crosses the Boerenverdriet lock, which will temporarily be used as the main shipping route while the Koopvaarder navigation lock, located to the south, is closed for renovation. This requires the safe operation of the bridge. Because it has not been used or maintained in recent years, the steel drawbridge is in a dilapidated condition.
For reasons of sustainability, Witteveen+Bos is focusing on renovating rather than replacing the existing bridge. Several inspections have been carried out to accommodate this. The foundation has been checked by means of an underwater inspection and appears to be in good condition. The foundation can be reused, provided that the load does not exceed capacity.
The wooden road surface is in very poor shape and will be replaced in its entirety. Steel, wood and composite materials will be considered for this purpose. The use of wood or composite is advisable in order to keep the weight down. The majority of the steel can be renovated and a few steel girders need to be replaced. Conserving all the steel requires closer inspection to check for the presence of substances such as chromium 6. The existing operating mechanism still works; however, given the age of the bridge and the lock’s function as an alternate shipping route, it is recommended that the operating mechanism be replaced. This will also increase the reliability of operating the bridge in the future.