For routing a single shipment containing multiple hazmat classes, the following procedures are suggested:

First, determine the weight of each commodity and check the U.S. DOT (PHMSA) rule to see if that combination is permissible and if so, which placard(s) are to be used. 

Then, for each placard, look up the PC*MILER Hazmat routing options.  

a. If all the placards correspond to one routing option, use that option.  

b. If the placards correspond to multiple routing options, then run the route for each option, and:   

    i.  If all the routes are the same, that common route is the route to be used.   

    ii. If the routes are different, then there may or may not exist a legal route for that combination of commodities for the specified origin/destination (this will occur only rarely).