I was asked recently about a number of issues relating to the traffic calming measures on Holt Lane/Holt Road as to why we need them and what purpose they serve. Set out below is the response I received:
“Dear Cllr Anderson,
To provide you with some background, in 2010 following the determination by the then coalition government that all residential streets should have their speed limit reduced to 20mph, the Council initiated the development of a new programme for expanding the use of 20mph speed limits with trial projects focusing on the environs of schools. Subsequently this programme has been expanded and developed with the ultimate goal of the expanded provision of schemes in local neighbourhoods to incorporate all schools within the setting of a lower speed limit, to support the City Councils Child Friendly ambition. This approach and programme was endorsed by the Executive Board in February 2014 in response to a deputation from the 20s Plenty for Us campaign group. The ‘The Provision of 20mph speed limits in Leeds’ Scrutiny Board report dated 17th March 2015 highlights Leeds’ vision that all residential streets within its district will be governed by a 20mph speed limit by 2020.
More recently, the former Scrunity Board (Sustainable Economy and Culture) reviewed the programme and evidence in March 2015 noting the change in emphasis from a road casualty reduction programme to a more broad based approach, which also gives emphasis to the broader benefits for improved opportunities for walking, cycling and community cohesion. Endorsement was given to the continued delivery of this programme and the aim the majority of residential streets within the Leeds district will have a 20mph speed limit by 2020, concentrated around schools and their local residential areas.
Holt Lane/ Road as a route has been a regular source of complaint from local residents to Leeds City Council, specifically concerns regarding the speed of traffic along the route. The speed surveys undertaken prior to this scheme showed that whilst the mean speed varied between 28 and 29mph, we saw the percentage of traffic travelling above 30mph to range between 32% and 38%. This is significant. To offer some comparison, Green Lane in Cookridge which is a long and straight road, sees mean speeds similar to Holt Lane/ Road but only 22% of traffic travels above 30mph. Furthermore, Otley Old Road a route which I would expect to see higher speeds due to its nature as a distributor route actually sees lower mean speeds and only 15% of traffic travelling above 30mph. Examining Holt Road historical surveys from 2010 shows that, whilst the mean speeds remain the same, the percentage of traffic travelling above 30mph has in fact increased in some locations.
With regards to Weetwood Lane, Leeds City Council received a deputation from local residents along with other community representations to extend the extents of the 20mph speed limit on Weetwood Lane. This was deemed to be a reasonable request, and would result in the lowering of speeds along a route that the Council receives frequent concerns about.
The determination as to what roads should be and can be included within the reduced speed limit is based predominantly on the existing speeds on that road, its functionality and whether it is believed that those speeds can be reduced to a level acceptable to the new speed limit. Based on the DfT’s instruction, the Association of Chief Police Officers (ACPO) subsequently issued guidance that for their Police forces to accept and agree to the reduction of a speed limit on a road to 20mph, the post-implementation mean speed should be 24mph or below and Leeds City Council consequently designs its schemes with this figure in mind. Where roads achieve a mean speed of 24mph or below on a 20mph speed limit road, this is then seen to be ‘self-enforcing’.
For the Council to achieve the 24mph mean speed on Weetwood Lane, it has been determined that signage alone would not be sufficient to achieve this and further intervention is required. From experience, traffic calming features in the form of vertical speed cushions are an effective measure with regards reducing vehicle speeds along a route. Furthermore, the design of the cushions has been refined over time to allow the implementation of a feature that has a speed reducing impact, but when placed in a system as proposed, should encourage drivers to maintain one continuous speed as opposed to speeding up and slowing down between each set.
The potential effect traffic calming features have on vehicles’ components has been studied thoroughly and independently in the past. The Royal Society for the Prevention of Accidents notes in their ‘20mph Zones and Speed Limits’ factsheet (link: http://www.rospa.com/roadsafety/advice/highway/info/20-mph-zone-factsheet.pdf), on page 10, that studies have been undertaken and found no evidence that speed cushions caused vehicle damage, or permanent changes to the vehicles suspension systems. Further to that, it found that if the cushions were straddled at an appropriate speed, then there were no forces placed on the spine that could cause injury and those forces were smaller.
There is further evidence raised in the ‘Local Transport Note 1/07 ‘Traffic Calming’’ issued by the Department for Transport in March 2007, specifically mentioned in paragraphs 4.5.28 and 4.5.29. The study undertaken showed ‘No damage to any of the vehicles was seen, despite repeated passes at speeds up to 40mph.’ (Link: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/70662/ltn-1-07.pdf). Furthermore, to confirm, the emergency services and the West Yorkshire Combined Authority (formerly METRO) were formally consulted on the proposals, with no objections raised.”