Modal shift helps not only to reduce greenhouse gas but also to mitigate labor shortage problem because transportation means used in modal shift can carry more cargos with fewer people. Recently shortage of truck driver becomes more and more serious. Among various factors, problems of long work hours and low wage are significant. It can be observed that some cargos shift their routes to marine transport for retention of drivers and improvement of their treatment. We add new functions to the existing cargo transportation simulation system which uses generalized cost model expanded with correction terms to estimate cargo transportation route and achieved highly accurate transportation reproduction although the simulation model is precise. The new functions are driver operation scheduling, detailed truck cost evaluation, considering backhaul cargo, automatic parameter tuning and so on. With the system, we analyze how the improvement of truck driver treatment (pay increase and improvement of labor hours) effects on modal shift. The result shows that there is possibility of noticeable modal shift progress on large lot size cargos.