To get to the bike co-op from my house I have to cross a steel draw bridge. The surface consists of open squares 2 inches across. The builders were thoughtfull enough to scallop the edges of the steel squares to add traction. The only cool part is riding across and being able to look down to the river below. On dry days you can ride across and feel the bike shimmy side to side as the tires try to follow the steel squares. On wet or snowy days the steel bridge becomes the largest human cheese grater in the world. The scalloped edges of the steel make nice parallel lines in even the toughest muscle tissue. There have been so many bike accidents that the co-op has instructed its members to walk across or ride on the sidewalk (illegal in Cleveland) when crossing. (hope you are not eating lunch when you read this)
Enjoy