Smaller vertical clearance margin
For passing under viaducts, a vertical clearance margin of at least 15 centimetres in respect of the actual height of the viaduct is used. This allows safe passage under viaducts. Under certain conditions, deviation from the applicable clearance margin may be allowed.
Application for passage with smaller vertical clearance margin
The conditions under which this can be approved are specified in the policy regulation for ‘issuing exceptional transport permits’. If you want to pass under a viaduct with a smaller clearance margin, you must therefore indicate in your application that the route meets the following requirements:
- there is no alternative route for reaching your destination
- there is no other mode of transport – for example, by water
- there are no other possible technical solutions – for example, using a low-loader.
In an application, you must substantiate why you want to pass under a viaduct with a smaller vertical clearance margin. Needless to say, we check to see whether an alternative route is possible. The road authority in question must always give permission to pass under a viaduct with a smaller vertical clearance margin.
Motorways and provincial roads
We are cautious about allowing passage under viaducts with a smaller vertical clearance margin on motorways and provincial roads. Vehicles travel at high speeds on these roads and there are limited possibilities for special manoeuvres.
Non-motorways and provincial roads
Along the remaining road network (non-motorways and provincial roads), in many cases the viaduct is located just after the starting point or just before the destination. Consequently, there is no alternative route or the road authority does not deem it advisable to take the alternative route. In cases like these, the RDW itself might assess whether the route meets the specified requirements.