Speed Cushions
A General Guide
Introduction
The extensive use of road
humps as speed control measures during the 1980s raised many
concerns about discomfort and delay being suffered by bus companies
and emergency services.
Speed Cushions which have been used elsewhere in Europe for a
number of years were introduced in this country during the early
1990's to provide an alternative
speed control measure which avoids some of the problems
associated with road
humps.
Description
Speed Cushions are a raised section of the carriageway which
smaller vehicles have to drive over but can be straddled by larger
vehicles such as buses and fire engines. In a similar way to road
humps, cushions are installed at regular intervals along the
carriageway to ensure that low speeds are maintained.
There are three main types of speed cushion layout:
- A series of single cushions combined with carriageway
narrowings or hatch
markings.
- Pairs of cushions (allowing two way working, suitable for
higher flow roads).
- Groups of cushions three abreast (also allowing two way
working), used on wider carriageways avoiding the need to use road
narrowing measures.
Advantages
Speed Cushions offer a number of benefits as a speed reduction
measure:
- They can contribute to the reduction in the number and severity
of accidents.
- They can reduce the volume of through
traffic.
- They do not adversely affect buses and emergency vehicles in
the same way as road humps.
- Cyclists and motorcyclists can pass between the
cushions.
Disadvantages
However, there are a number of inherent disadvantages:
- Overall, they are less effective as a speed reducing measure
than road humps, particularly where lorry flows are
significant.
- It maybe necessary to prohibit parking on approaches to the
cushions.
- They are generally difficult and expensive to
construct.
- They can generate noise and vibration although it is less of a
problem than with road humps.
- They can be considered visually intrusive due to the use of
colours that contrast with the normal road colour.
- They cannot be used at pedestrian crossing places because they
can constitute a trip hazard.
- They generate additional highway maintenance
costs.
- They can only be used on roads subject to a speed limit of
30mph or lower.
Legal Status
Although the introduction of Speed Cushions does not require the
making of a
Traffic Regulation Order, a statutory process needs to be
followed which involves consultation and public
advertisement.
This information has been reproduced by kind permission of
Bristol City Council
