Given the tens of billions of pounds we give the Ministry of Defence each year I would have thought they could have provided a vehicular bridge by now.
The R.E's have the means to provide vehicular bridges very quickly. They are like giant mecano sets and can be built on one bank and cantilevered across the gap, the Sappers then balance across the structure carrying the 'bank set' for the other side. When this is quickly built the bridge is pushed further across to land and rest upon it. Ramps and decking is added and is then ready for use. These bridges can carry tanks etc so road vehicles are no problem.
The only problem as I see it are the lengh of spans. For long spans across rivers, pontoon bridges can be assembled. These are literally a series of floats linked together and decking added. The army have some very technical amphibious bridging units too, but these are only for short term crossings. The problem with some of the bridges that are affected is that the rivers they span are tidal, rising and falling, narrowing and widening a couple of times daily, this makes pontoons difficult to manage.
No doubt they are going to take some months to replace.
Dave.