Once you start this quest take the Railings with you and search the fence in the front of the Coal Trucks to fix the broken rails. You are given six Railings, so find the six spots in the fence by right clicking and selecting "search" on each piece of fence(1 per tile). If you fail to replace a railing, you will be hit for 2 damage. When you have repaired all 6, return to the Dwarf commander.