All instructional designers go through this. We look at the material and say to ourselves, "OK this material, as is, is about as interesting as dusting a houseful of Venetian blinds." We doubt our chose profession and then we get on with making the content more interesting.
Begin by asking questions of it: why is transporting hazardous material important? What good occurs when it's done well? What bad occurs when it's done not well? What problems are currently occurring? I might make that my starting focus. Starting with real problems that your learners know our problems makes the course seem more important.
Scenarios of course will help. Maybe you have a few characters that run throughout the course, and they make different runs carrying different stuff. You could then ask questions about if they are carrying the loads in appropriate ways.
You could also just build a potential run and then pose questions to the learner--"OK so you are going to X and carrying Y. What do you need to do? Have them make a choice and provide the consequence of their actions. "Well, if you do and the cannister tips over, you had better hope your life insurance premium is paid, etc., etc.
Doing something interesting is a risk. And some managers abhor risk. Have a good conversation with the person who will approve this project to get a sense of what the boundaries are.
Theme: well, you could do a highway theme. There are a whole bunch of sites the provide blank road signs that you could put your on-screen text on. Truck sfx won't be hard to find either.
And know that, really, anything you do is better that what you've got now. Best of luck. --Daniel