Speed

Key messages

• Limiting the speed that vehicles move around the workplace is an important part of controlling traffic.
• The best way to do this is to use fixed features that mean drivers cannot move too quickly.
• Speed limits are also used widely, but they are not always appropriate or enforceable

Questions to ask

Your risk assessment should include answers to these questions:

• What is the safest speed for vehicles to move around our workplace?
• What can we do to slow down the traffic?
• How can we set and enforce speed limits?

Traffic calming features

Examples of fixed traffic calming measures include:

• Speed humps;
• passing places;
• narrowed routes (using, for example bollards, raised kerbs, chicanes, built-in routeside features, sometimes called 'pinch points'); and
• 'rumble' devices (such as rumble strips, rumble areas or jiggle bars).

Traffic-calming measures should be signed and clearly visible. Many features can be lit or made reflective. Take care when you are deciding where to use traffic-calming features, because they can sometimes increase risks (for example, by affecting the stability of vehicles or less secure loads).

Speed humps

Speed humps are a proven way to limit the speed that vehicles move around a traffic system. Speed humps normally slow vehicles to an average of around 15 miles per hour. Individual humps should not be used on their own. Humps should be repeated at intervals along a route and should not be used within 15 m of a junction or bend. Humps are only suitable for routes where vehicles can go over the humps safely.

Speed hump warning signs should be clearly visible, and should be far enough away from the hump to allow drivers to change their speed safely. The humps themselves should also be clearly marked. See an example of the type of sign you should use.

Some vehicles may not be able to go over speed humps safely (for example, most industrial lift trucks or some caravans). Also, some emergency vehicles need to avoid speed humps (for example, ambulances carrying patients with spinal injuries). However, it is often possible to include some type of bypass to allow these vehicles to avoid going over the hump.

Sometimes speed cushions are used instead of speed humps. Speed cushions work in a similar way as speed humps, but do not stretch across the whole road. Instead, they leave some space clear for certain types of vehicle to drive through or straddle the raised areas (for example, cyclists or larger emergency vehicles).

Chicanes may also be used, but some vehicles (for example, some lift trucks) may have trouble passing through them safely, especially if they are carrying stacked loads.

Speed limits

Speed limits are also used widely, but they need to be used sensibly. Speed limits have to be practical, otherwise drivers will be tempted to break them. Common problems with speed limits are that:

• they are poorly signed;
• they are not appropriate (they are often set by guessing, but this can result in an unreasonable limit that is very difficult to enforce);
• they are not enforced;
• speedometers often do not work effectively at low speeds; and
• some internal site transport vehicles do not have speedometers.

It is common for sites to set the same speed limit across a whole site. This is not usually effective, and can be difficult to enforce. Often, you will need to decide on individual speed limits for different routes, because the types of traffic and task are different.

Speed limits need to be appropriate for:

• the vehicles using the route;
• the types of load they carry and how they carry them;
• the driving surface;
• the layout of the route, including how tight the bends are and visibility at junctions;
• hazards along the way; and
• work that takes place on or near the route.

Setting a limit

To decide an appropriate limit, you should measure the speeds that vehicles travel at various locations along the route. The limit you decide on should be sensible considering these speeds. The limit should be a safe speed, but if it is unreasonably slow, drivers will be tempted to ignore it completely.

When assessing the appropriate speed limit for a particular place, you may need professional advice based on the route layout and character of the site.

Speed limit signs may need to be repeated around the factory roads instead of just one sign being put up at the entrance to a limit area. This will depend on the size of the limit area, and whether drivers are likely to know (or need reminding) about the speed limit.

Sensors

Some systems involve controls that interact between the site and vehicles that use it. As well as information signals that sense speed and react to tell drivers that they should slow down, some systems now activate speed limiters on vehicles in response to radio signals broadcast at area boundaries.

Resources

Find out more about signs, signals and markings.