There is a lot information that we might discuss about transportation after Doomsday. Some people think we may just go back to horses - but horses won't be available right away, and they are very slow for long distance travel. Fuel for railroads will be a problem - but it may be possible to build some relatively low powered steam engines. I have not provided resources to explore that possibility. They could be fueled by coal or wood.
There is another possible use of wood, rather than generating steam, that most people don't know about and there are directions for that below. These wood driven engines could have many applications other than powering tractors or trucks. They could power most any kind of machinery including electrical generators.
Here are another two unusual documents that may be apropos to the situation.
One is 186 pages on Bridge Inspection, Maintenance and Repair. There may be many miles of undamaged roads but the bridges are going to need be inspected.
And then this 207 pages on maintenance of trackage.