Quick connection at BRU
 

I have a 55 minute connection at BRU coming up. I've done a bunch of research and determined that my United Flight from ORD will be arriving at a B gate at 9:05am (if on time) and my Brussels Airlines flight to MRS will leaving from an A gate at 10am. Would it be quicker to take the bus transfer between B and A gates, or to walk between the gates? I'm assuming I go through passport control at BRU and not my final destination, MRS.

Thanks.

You have to go through passport control and security. I would walk. It's about a 10-15 min walk + 10 min security check. You should make it on time.