Express road structures are important for vehicles running on sludgy soils. The main structures of express roads and the corresponding terramechanics behavior were discussed in this paper. The energy method used to evaluate the mobility of different express roads was suggested, and the terramechanics of pin-jointed beam-type roads was analyzed. The influence of the tractive coefficient and the sinkage on the mobility of express roads was discussed. The method and results in this paper are useful to engineering applications for other structures.