Gates could be installed on small roads with sporadic use, e.g. service roads, and those which provide access to a fenced road. The possibility of entry by small animals under the base of the gate should be limited using a concrete threshold accompanied by a rubber base skirt (Figure 5.2.26). There are different type of bar or mesh gates. Spacing between bars must be adapted to target species.
Cattle grids are an alternative to gates (Figure 5.2.27). They are a 2 to 3 m wide device consisting of a pit at least 30 to 50 cm deep covered with a metal structure consisting of a series of steel bars spaced about 5 cm apart. No gaps between fencing and the grid should be left. The pit should allow all small animals that fall into it to escape. This can be achieved by sloped lateral walls (Figure 5.2.28), lateral openings or ramps angled at 30-45º (see Chapter 7 – Maintenance). National traffic regulations should be checked as installation is forbidden in some particular conditions and countries. In areas with longer duration snow cover, cattle grids are not suitable as animals are at risk of harm through slippage when attempting to cross.