I think Sneaky used darn near a whole roll of masking tape making these roads in our living room. The roads start at the bottom of the staircase (where James would first see it) and extend all the way to the living room, winds around, goes into the kitchen, and then goes back to the hallway. I found a bunch of Jim's old matchbox cars (blew some dust off of those) and set up some traffic jams.
James liked it but has since used the roads for his McDonald's and lego cars :) The tape is still on the carpet. I hope to convince James to clean it up with me tonight.