What can I replace a railroad tie for a bumper on the driveway?

by Sheryl
My driveway is on a bit of a slope, and runs right to the grass lawn. I have 2 creosote railroad ties as a bumper to keep cars from running on the grass. It's decaying and time for a new 'bumper'. I need to come up something other than the ties, that will hold up to weather, watering and bumps from car tires, and still look nice. Ideas?
railroad tie 'bumper' on driveway
  9 answers