Personally, I would be very leary about giving someone in his situation a ride anywhere... I just know that every time my mom would give my sister a ride somewhere after she got out of jail, they would never end back up where ras had promised she would go (rehab, home, whereever...or if they did go where they were supposed to, it was only so she could acquire drugs right under mom's nose) I don't know much about work release, so things might be different... but I do know that if he tried to run after being released, they would have to find him before they could do anything about it, which can be very hard with an addict. Besides, if he was to dip out on going back to work release after you came and got him, is there a chance you could get in trouble as an accomplice? Or even be accused of it?
Sorry if I sound too negative, I just don't have a lot of trust for an addict who is not in active recovery. I would hate for his actions to further inhibit your recovery... it sounds like you're doing so well already, and I worry that this might be a step backwards.
Just my opinion though... and bare in mind that my addict is my sister, not my child. So my perspective may be a little different.
*hugs and prayers*