Originally Posted by
Gunnar Alquist
Robert,
A bollard is required, but it is to protect the gas piping from vehicle damage. This would be true for any gas piping if it is in a location that it could be hit by a vehicle.
Actually, gas piping be damned!

, it is to protect the water heater, and any appliance.
And it does not need a "bollard", just "vehicle protection".
From the 2006 IRC. (underlining is mine)
- P2801.4 Prohibited locations.
Water heaters shall be located in accordance with Chapter 20.
- M2005.1 General.
Water heaters shall be installed in accordance with the manufacturer’s installation instructions and the requirements of this code.Water heaters installed in an attic shall conform to the requirements of Section M1305.1.3. Gas-fired water heaters shall conform to the requirements in Chapter 24. Domestic electric water heaters shall conform to UL 174 or UL 1453. Commercial electric water heaters shall conform to UL 1453. Oiled-fired water heaters shall conform to UL 732.
- M2005.3 Electric water heaters. Electric water heaters shall
also be installed in accordance with the applicable provisions of Chapters 33 through 42.
"manufacturer’s installation instructions" will tell you to protect it from vehicle damage if installed in a garage.