for their precast concrete barrier walls. The department has marked all compliant precast concrete barrier walls with "350", indicating that they adhere to the requirements laid out in the National Cooperative Highway Research Program's Report 350. Without this marking, a barrier wall is not approved for use in Ohio. Variations Modern variations include the constant-slope barrier and the F-shape barrier. The F-shape is generally similar to the Jersey barrier in appearance, but is taller, with somewhat different angles. The UK equivalent is the concrete step barrier. First tested in 1968 by the then Department of Highways in Ontario, Canada, the Ontario Tall Wall is a variant of the Jersey barrier. Standing at , it is taller than the standard Jersey barrier. Ontario's Ministry of Transportation is replacing guiderails (steel guardrail and steel box-beam) with these tall wall barriers on 400-series highways since the early 1990s, while the City of Toronto is doing likewise on portions of the Gardiner Expressway and Don Valley Parkway. Plastic Jersey barriers Hollow polyethylene barriers have been developed for short-term applications where portability is important. These plastic barriers are normally filled with water after placement on-site to provide a moderate level of crash protection, then emptied prior to removal. They are not designed to deflect vehicles, so vehicles may penetrate the barriers. These barriers can also be filled with sand at the cost of reduced portability. See also Barrier transfer machine Bremer wall Cable barrier Concrete step barrier Constant-slope barrier F-shape barrier Impact attenuator Median strip Traffic barrier Traffic bollard References External links American inventions Anti-tank obstacles Fortification (architectural elements) Protective barriers Road safety Road traffic management