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Scrutiny Review - 20 mph Speed Limit »

Robert Mack
2011
London Borough of Haringey

Success has been achieved in reducing road casualties through the establishment of 20 mph zones.  These are self enforcing due to the use of physical calming measures. The most high risk or dangerous locations have been prioritised for action.  In London, many local authorities have already addressed most  of such areas. Some have been considering joining up all their 20 mph zones to form a borough wide 20 speed limit. Haringey has a long term strategy of increasing the number of 20 mph zones in the borough until most residential streets are covered.

Some local authorities, such as Portsmouth, Islington and Oxford, have taken the additional step of setting 20 mph as the default speed limit for their area, enforced by signage alone. The scheme in Portsmouth was independently evaluated and this showed that it had been associated with reduced traffic speeds and casualty figures. Islington Council has recently implemented a borough wide 20 mph speed limit which has been well supported amongst local residents. Whilst more evidence is needed on the long term effectiveness of default 20 mph speed limits, that which is available has demonstrated promising results.

The cost of establishing a default 20 mph speed limit enforced by signage alone is less than that of extending the number of 20 mph zones by physical calming measures and could also be established more quickly – in approximately two years as opposed for the Council’s current strategy which will take 10 – 15 years to complete.

The Panel was therefore of the view that there would be merit in introducing a default 20 mph speed limit for the borough in all side roads. This would be enforced by signage alone in areas not currently within 20 mph zones. It was felt essential that local residents were fully engaged in the process as the success of such a scheme would be dependent on their support. The Panel also believed that the Council should work with Transport for London to set up a pilot 20 mph speed limit in a town centre.

Realistic expectations should be built for the scheme. Whilst the Panel was of the view that it is likely to reduce average traffic seeds, it felt that the change was unlikely to be substantial, at least in the first instance. This is due in part to the fact that many of the side streets included in the new speed limit are likely to have low traffic speeds.   In addition, reductions in casualties may be modest due in part to the fact that many of the higher risk locations are already in 20 mph zones.

In addition to reducing road casualties, a 20 mph speed limit also has the potential to lead to a long term change in the behaviour of drivers, simplify the issue of speed limits and makes expectations clearer. Over time, drivers would become more familiar with the lower speed limit and therefore more sympathetic to it. There is also evidence that it increases the perception of safety and makes residents feel more positive about their area.

The Panel noted concerns about enforcement but is of the view that it should not necessarily be a major issue.  Where persistent problems do occur, ward panels could make the issue a priority for their Police Safer Neighbourhood team. Physical calming measures could be considered as a last resort in areas where problems prove to be difficult to resolve.

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