Do I get paid my hourly rate for business travel?

I am an hourly contractor for my employer, and employer wants to send me on a business trip that will involve traveling during and after normal work hours. I don't want to rip anybody off, including myself -- just want top be fair. Are they expecting me or not expecting me to list the travel hours on my time sheet? Might they think I should take some hours off before getting on a plane at 6 pm? What is customary?