Road Safety Impact of 20mph Scheme & additional Roads to be included

Filename: Road Safety Impact of 20mph Scheme & additional Roads, 2019

Source: Paper 19-32, for OSC on 12 Feb. 2019.

Comments on this Paper:

There is much data about what has happened since the speed limit on most residential roads in our borough was reduced to 20mph. And Wandsworth Living Streets welcomes the evidence that has emerged. However 2 general points are important to note and to ask Officers to provide more information on:

  1. Are there really only 4 roads among the borough’s 1,627 20mph where average speeds exceed 24mph? Since the traffic survey covered only 5% of these roads, the real number could in fact be as much as 20 times larger. Officers should be asked to carry out a rolling programme over the next 2 years to identify these roads.
  2. Road Safety on the 38 borough-managed 30mph A and B Roads is still a huge problem, even if all 12 of the roads identified in the Paper become 20mph:
  • 26 Borough-managed Roads would still remain 30mph. As well as all TLRN Red Routes.
  • These A & B roads, and TLRN Red Routes, together,are responsible for 80% of all people injuredin traffic collisions on roads in Wandsworth Borough and 83% of all people Killed or Seriously Injured.
  • ROAD SAFETY: This means that we in Wandsworth will not significantly reduce the numbers of people killed or injured in traffic collisions until we make BOTH Wandsworth Council’s A and B Roads and TfL’s TLRN roads safe. That means a 20mph speed limit, among other measures.

Key findings re Speed and Road Safety on Wandsworth’s 20mph Roads as a whole:

  • Speed reduction: Average speeds fallen by 1mph.
  • Accident rates:fallen by 9% in first 12 months of operation of 20mph scheme compared to 3 year average (2013-15)
  • Vulnerable Road User accident rates: fell by 19%. (Vulnerable Road Users are Pedestrians, Cyclists, Motor cyclists)
  • A handful of roads did not achieve an average speed of 24mph (ie the Police custom of taking no action re drivers who exceed the speed limit by 10% plus 2mph). The 4 offending roads are: Wimbledon Park Road in Southfields; Keswick Road in Putney, Priory Lane in Roehampton, and Battersea Church Road. All are long straight roads.
  • Compliance: involves Community Road Watch; and Re-deployable Vehicle-activated Signs.
  • Enforcement: Council will explore possible additional actions – enforcement, speed awareness courses.
  • Annual evaluations of impact of 20mph scheme will be undertaken.

Accuracy of the Paper’s findings:

There is a lot of detail in the Paper. I am not entirely convinced as to how reliable this data is.

  • Automatic traffic counters were installed covering 5%of the 1.627 unclassified (ie not A or B) roads. So there may be many more than just 4 roads where average speeds exceed 24mph.
  • The average speed reduction of 1mph seems to be only 0.6mph (from 21.1mph to 20.5 mph) on residential roads (Para 6).

Likely Effectiveness of Measures Council proposes to take:

  • No questioning of effectiveness of Vehicle-activated Signs (VAS): e.g. Wimbledon Park Road already has a VAS installed.
  • Vagueness as to remedial measures to be taken on the four offending 20mph roads: notably that where average speeds on a residential road exceed 24mph, ‘it will be addressed in accordance with Traffic Management Policy’. Not clear for ordinary Councillors, let alone the public at large. And the measures on the 4 offending roads are vague in the extreme – Wimbledon Park Road – ‘further monitoring’; Keswick Road – a junction with Keswick Road to be ‘under investigation for minor safety improvements’ and a VAS to be installed; Battersea Church Road – a ‘corridor study with aim of reducing speeds’ and ‘improving walking and cycling facilities’; Priory Lane – ‘investigation with aim of reducing speeds & improving cycle facilities’.


  • No assessment of Casualties on Wandsworth’s A and B Roads: That is deeply regrettable since these 38 roads (still with a 30mph speed limit) are the sites of significantly more collisions than on all 1,627 unclassified ‘residential’ roads. 28% of all injured people; and 29% of total number of KSIs are located on these 38 A & B roads, compared to only 19% of all injured people; and 17% of total no. of KSIs on 1,627 residential roads.
  • No definition of what is a ‘residential road’: Our view in Wandsworth Living Streets is that most of the Borough’s 38 A and B roads are ‘mixed use’ roads, ie with extensive residential areas on long stretches of most of them, as well as many clusters of shops, and nearly 30 schools.


A handful of Wandsworth’s 38 A and B Roads to be considered for 20mph treatment:

Wandsworth Living Streets welcomes the proposed reduction to 20mph of the speed limit on a small number of these currently 30mph A and B roads. But this can only be a start.

But 4 conditions have to be met for Officers to consider reduction in speed limit to 20mph:

  1. Where existing average speed is already below 24mph: COMMENT: This is extraordinary. You might have thought that priority roads ought to be those roads were the average speed was excessive – ie above 24mph or above 35mph.
  2. No additional traffic calming needed.
  3. There is an additional benefit – e.g. busy shopping parade.
  4. Ward Councillors & residents already support.

6 Candidate A & B Roads for this Phase 2:

  • Northcote Road in south Battersea (petition received, & wanted by Ward Councillors)
  • Bolingbroke Grove in south Battersea (petition received, & wanted by Ward Councillors)
  • Bellevue Road, Balham (petition received)
  • Putney High Street (already agreed to as part of Council’s PHS scheme, Phase 1)
  • Rectory Lane in Tooting (recommended in this Paper subject to consultation)
  • Silverthorne Road in north Battersea (southern section in Lambeth already 20mph)

6 more A & B Roads recommended for ‘further study’:

  • Mitcham Lane
  • Mitcham Road (scheduled already to be 20mph as part of Tooting Broadway Pedestrian Town Centre Project)
  • Lombard Road, in Battersea
  • Vicarage Crescent, in Battersea
  • Bedford Hill (north section, presumably from Station Road, Balham)
  • Burntwood Lane (Burntwood School section principally).


Prepared by Robert Molteno, Secretary, Wandsworth Living Streets, 10 February 2019