You can see that the piece of 2 lane road in the sea is cleanly broken away from the other 2 lane road that it was next to. That is probably why it was not badly damaged. Now it might have some kind of heat damage on further study. The ball of fire moved upward to the rail road and set fuel tank cars on fire. There are 2 sets of rails, and apparently the other set is working at least for passenger trains. More study will probably be needed for heavy military loads.
Here are further old comments I made when the Kerch Bridge was first attacked in Oct. 22. I had done considerble research on the history of building the Bridge, and then a lot of commentary, videos and photos presented this past October.
In Jan. 23, I believe it was reported all 4 lanes of the roadway had been completely restored much ahead of schedule. The research I did then speculated the 2 rail tracks would not be restored until Sept. 23. I think one rail has been used for passenger trains since shortly after the tanker fire was cleaned up. However, heavy transport had to use the large ferries which could carry something like 500 autos at a trip. This would probably include items like tanks, and artillery. The ferries could be sunk and still allow the million people in Crimea to escape by auto and passenger train as Ukraine moves to regain Crimea. I suspect Ukraine Army would prefer not to have to take care of pro Russian civilians or risk collateral damage, so it is best to leave the roadway available for light transport. Thus not destroying the bridge, but preventing transport of heavy equipment.