Police Ward Panel meeting this evening

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Permalink Reply by John D on December 6, 2012 at 9:10

What happened to the promised enforcement of the 20 mph limit on Wightman ?

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Permalink Reply by Alan Stanton on December 6, 2012 at 12:03

You've written to Cllr Nilgun Canver to ask, yes? Did she acknowledge your email, John?

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Permalink Reply by John D on December 6, 2012 at 13:00

Karen asked for issues of concern and is going to speak directly to the SN police. I did raise it at a meeting of the Transport Forum at which Councillor Canver was in the Chair.

This was my submission:

Wightman Road has been restricted to 20 mph for some time but the restriction is widely ignored ( as is the 7.5 T limit )

This morning ( 22/9/11 ) I undertook a short survey using a video camera. There is a 20mph SID on the south-going side of Wightman.

 In 9 minutes, 98 vehicles passed the SID.

 The SID was triggered 34 times.

 But  one triggering can represent a bunch of several closely-spaced vehicles ;

 In fact, examination of the tape shows that  approximately 48 vehicles exceeded the 20 mph limit – just under 50%.

 The 20 mph limit was claimed to be self-enforcing. Plainly, it is not.

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Permalink Reply by HoL Site Admin on December 6, 2012 at 13:01

Via Twitter:

@harringayonline Please could u bring up the threatening behaviour and blatant drug dealing taking place in the betting shops ?

— Michael Whytock (@michael_whytock) December 6, 2012

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Permalink Reply by HoL Site Admin on December 6, 2012 at 18:15

From our local Bobby, Glyn:

Extracts from DfT Traffic Advisory Leaflet 09/99 and DfT Circular 01/2006 and TRL report 363:

20 mph speed limits without self-enforcing features have the attraction of being relatively inexpensive to implement. However, regard must be given to the 'before' speeds, because the higher they are the less likely speeds will be reduced to 20 mph. It will be important that the local police are consulted at the outset, to obtain an understanding of the level of enforcement that could be applied and how effective that might be in ensuring a significant reduction in speed. There will be some areas where speeds are relatively low already and the provision of a 20 mph speed limit indicated by terminal and repeater signs alone, without extensive police enforcement, will be sufficient to bring speeds down to 20 mph.

Research into 20 mph speed limits carried out by TRL (Mackie, 1998) showed that, where speed limits alone were introduced, reductions of only about 1-2 mph in 'before' speeds were achieved. 20 mph speed limits are, therefore, only suitable in areas where vehicle speeds are already low (the Department would suggest where mean vehicle speeds are 24 mph or below), or where additional traffic calming measures are planned as part of the strategy.'

In TRL report 363 Mackie concludes: ‘To sum up, where speeds of around 20mph are desired in urban areas, traffic calming remains the best option to achieve this. Where funding or other reasons preclude its use, the use of only static signs appears insufficiently effective to reduce speeds to 20mph or to achieve accident reductions. Where signs-only schemes are used, small speed reductions and accident savings can be achieved if associated publicity and enforcement campaigns are also used. However, speeds are still likely to remain well above 20mph.’

Mean speeds and 85th percentile speeds are the most commonly recorded characteristics of speed. Traffic authorities should continue to routinely collect and assess both, but mean speeds should be used as the basis for determining local speed limits. This is a change from the use of 85th percentile speed in Circular Roads 01/93 (DoT, 1993). The use of mean speeds is underpinned by extensive research demonstrating the well-proven relationship between speed and accident frequency and severity. They also reflect what the majority of drivers perceive as an appropriate speed to be driven for the road, and are felt to be easier for road users themselves to understand.

Consultation
The value of adequate consultation being undertaken cannot be over-emphasised. Without such consultation, schemes are likely to be subject to considerable opposition, both during and after implementation. The police need to be consulted about a scheme, particularly where a 20 mph speed limit is proposed. If sufficient measures to reduce and control speeds are not installed, then the zones or limits will not be self enforcing and the police could be faced with calls upon their time to enforce the 20 mph speed limit. Residents within the zone or limit would of course need to be consulted, and it might be advisable to consult with school communities occurring within the zone. School children have in the past provided designs for the bottom panel of 20 mph zone signs, to diagram 674. Consultation with the fire and ambulance services (TA Leaflet 3/94), and any bus operators will be necessary. Additionally, haulage operators may need to be approached depending on the land use of the area where the zone is to be installed. The views of users of agricultural equipment in more rural areas will need to be obtained.

Authorities should be prepared to modify schemes to meet valid concerns raised.
Successful 20mph zones and 20mph speed limits should be generally self-enforcing. Traffic authorities should take account of the level of police enforcement required before installing either of these measures. 20mph speed limits are unlikely to be complied with on roads where vehicle speeds are substantially higher than this and, unless such limits are accompanied by the introduction of traffic calming measures, police forces may find it difficult to routinely enforce the 20mph limit. Traffic authorities should therefore always consult the local police force when considering possible 20mph limits or zones, and thereafter as part of the formal consultation process.

Monitoring
The success of any 20 mph zone or limit will depend on the local authority being able to demonstrate that the measures introduced have shown a significant benefit. In the longer term this will generally be related to the reduction or the prevention of accidents, particularly to children. In the shorter term a good indication of whether a zone or limit has been successful is the reduction in vehicle speeds to 20 mph or below. An appropriate method of measurement for speeds in 20 mph zones would be to monitor the mean and 85th percentile speeds both at speed controlling features and at locations between them. The measurements should be taken in dry weather conditions at the position on a road where speeds are expected to be highest. For 20 mph speed limits, measurement should be made at the mid-point of a road. Not every road would need to be monitored and specific locations chosen could represent up to five other roads of similar characteristics and measures. Only speeds of light vehicles need be measured, taken at times when traffic is flowing freely. A sample size of 100 vehicles would normally be appropriate, but where traffic flows are low then measurement of light vehicles over a two hour period would be acceptable. If the results showed that the overall mean speeds at and between measures exceed 20 mph, then further speed controlling measures would need to be installed.

Monitoring can increase the overall cost of schemes. However, if it is not done demonstrating worthwhile benefits might prove difficult.

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