These grid systems are very versatile. They can keep gravel in place or grow grass that you can drive on. These sturdy tiles that can be driven on without fill make the most sense to me. One type recommends topsoil be mixed with the gravel base 50/50 to help the grass be successful. These are easy to install and repair and best of all provide a porous surface: eliminating all sorts of problems requiring resurfacing, drains, or complete demolition. Obviously, this type of paving drastically reduces the main source of urban water pollution: runoff from lawns.