Country: United Kingdom
Vehicles used: Private car, 3.5 tonne van
In the UK, roads are not usually restricted by vehicle type, but most commonly by width or height, and less commonly, by total train length. For example, most railway bridges have a height restriction.
Similar signs also exist for width, length or weight restrictions. Simply being able to create a profile of your own, whereby you set the gross weight of your vehicle, its length, width and height would be very useful. In the same way as the community edits and updates its mapping and road closures, the option to "add length/width/height/weight restriction" would prove very useful, and within a period of months, Waze mapping over here in the UK would contain most of these restrictions.
Moreover, most of this is also applicable to the rest of Europe, since signage is fairly standardised due to the EU.