CONNECTING SOUTHAMPTON

We want to make Southampton a better and safer place to live, work, visit and play. Slower speeds are safer for all. Traffic speed is often too fast in our residential and local shopping streets. This can be a barrier to walking and cycling and increase the risk and severity of accidents. Reducing traffic speed helps people feel more confident about using their local streets. It is safer for children to walk to school, while older people feel more able to travel independently and safely. Calmer road speeds lead to better health, less noise, more social interaction and stronger communities.

There is evidence that 20mph speed limits bring down overall speeds where implemented. The Royal Society for the Prevention of Accidents (ROSPA) has put together a useful 20mph factsheet, explaining the need for lower speeds in bringing down casualty rates and the evidence behind 20mph zones/limits in reducing vehicle speeds. 

The latest evidence from a city-wide roll-out of 20mph speed limits, has been produced by the walking and cycling charity, Sustrans and The University of Edinburgh, which examined the effectiveness of the city’s 20mph speed limit programme.  Amongst the findings were a continued drop in speeds, with overall average speed down from 23.77mph in 2016, before the 20mph roll-out, to 21.92mph in 2021 across the streets surveyed, with the fastest drivers reducing their speeds most.  The proportion of streets surveyed with average speeds of 20mph or less had also increased from 25% to 37% in 2021. 

For every 1mph fall in speed research has shown a 5% reduction in accidents, while accidents that occur at lower speeds tend to result in less severe injuries, demonstrating the significance of the changes. Additionally, road traffic collisions have continued to fall since the 20mph roll-out. Analysis of data from the 36 months following the introduction of the 20mph network showed a 30% decrease in collisions compared to the 36 months before, resulting in a 31% reduction in casualties.  Click here for more info on the research carried out.

A change in law in 2016 made 20mph speed limits and zones very similar. 

A 20mph speed limit area is marked by a single 20mph sign on the entrance to the area. A 20mph zone requires two 20mph signs at the entrance plus at least one piece of physical traffic calming. 

Both limits and zones can then be enhanced with 20mph repeater signs or other traffic calming measures, such as crossing points, road narrowing, humps or chicanes to assist drivers in complying with the speed limit. 

A change in law in 2016 made 20mph speed limits and zones very similar. Since 20mph speed limits are slightly easier to implement, Southampton City Council can cover a wider area with 20mph for a similar cost. You will see new 20mph signs on entry to the areas and we will add repeater signs to remind drivers about the new limit. Once the schemes are in, we will review their effectiveness to see where we need to add more measures to help improve compliance. These measures might include more reminders (including new mobile Vehicle Activated Speed signs – VAS), or dependent on available funding, physical traffic calming measures such as crossing points, road narrowing, humps or chicanes. Any additional physical measures would be subject to funding and consultation with residents and Ward Councillors. 

An online request form was opened from October 2021 to January 2022. This has now closed and all requests received are now being reviewed.​

SCC e-petitions for any new 20mph schemes will be considered in line with the council's e-petition policy.

20mph speed limits are enforceable by police where the limit is clearly marked (i.e. meeting signage regulations) and any offenders may be prosecuted. The police have also developed the option of speed awareness courses for those exceeding 24mph in a 20mph limit and these may be an option in some forces. Fixed Penalty Notices and prosecutions can also be used as the police see fit. 

The design of 20mph limit areas will take a ‘signed only’ approach, consisting of 20mph entry signs at junctions with a 30mph boundary road, and the required 20mph repeater signs within the 20mph limit area, typically attached to lamp posts, spaced approximately 200 to 300m apart. This follows the latest DfT guidance on setting 20mph limits.

The design of 20mph limit areas will not include any physical traffic calming interventions, such as speed bumps or raised tables, unless this is part of an agreed programme of works for a particular street / area, such as an Active Travel Zone.

When designing the 20mph areas, other low-cost measures will be considered to complement the 20mph signage, such as 20mph painted road markings. Any road marking proposals will be assessed on a case-by-case basis when designing each area and will be subject to available funds. 

A 20mph limit area will be defined by a set of residential streets, bounded by main distributor roads – typically, but not exclusively, A-roads – which carry large volumes of cross-city traffic. These main roads will remain at 30mph limits, but this will be assessed on a case-by-case basis when designing a 20mph limit area.

The final design of a 20mph limit area will be consulted on with Ward Councillors before a final design – e.g. the streets to be included – is agreed upon. The final design of a 20mph limit area will be subject to a Traffic Regulation Order (TRO) and to the legally required 21-day consultation.

The advertising of the TRO will be through a local newspaper notice, street notices and the Southampton City Council 20mph webpage. Residents, businesses and the emergency services will be able to respond to the TRO through a link on the council webpage, or by post (address provided on the TRO notice). 

Objections to a proposed 20mph limit TRO will be considered in line with the TRO regulations. When considering objections to 20mph speed limits, the overarching policy to create safer streets for all users, as outlined in the Corporate Plan and Connected Southampton 2040 Local Transport Plan, will take precedence.

Available speed data on roads within each area will be used to determine pre-scheme average vehicle speeds. Post scheme speed data will be obtained after a minimum of one month following implementation of the 20mph limit. The council will also utilise its existing supply of mobile VAS units to be sited within newly implemented 20mph areas. As well as alerting drivers to the new speed limit, the VAS units can obtain speed data which can be used as part of the post-scheme monitoring.

Post scheme monitoring data will be made publicly available on the council's 20mph webpage and will help inform the need for any further interventions and / or continued monitoring.

Post scheme data which shows little or no reductions in average speeds, will not be deemed as a failure of the 20mph limit scheme. The council, as the highway authority, has a duty to set appropriate speed limits in line with its local transport strategy objectives and wider national policy objectives. Monitoring will be used primarily to understand where further measures / interventions are needed to bring speeds down. It will not be used to decide whether to reconsider the 20mph limit.

An online request form was opened from October 2021 to January 2022. This has now closed.  We are proceeding with the roll-out of 20mph speed limits across 14 areas in the city, as shown on the 20mph webpage.  We will review whether to open up the request form for other areas at a later date.

Research indicates that slower speeds encourage a smoother driving style with less stopping and starting which helps traffic to flow. Evidence from other 20mph areas shows that, over the longer term, slower speeds encourage more people to walk and cycle, easing congestion on the road.

Studies have so far not conclusively proven either a positive or negative effect on air quality: driving at 20mph causes some emissions to rise slightly if travelling over long distances and some to fall. Reduced acceleration and braking may help to reduce fuel consumption and associated emissions that are more associated with driving in urban areas.  Research reported in the Journal of Epidemiology and Community Health conducted into the possible impact of introducing a default 20mph speed limit in Wales, found that it could result in 12% reduction in gear changes, 14% reduction in braking and 12% reduction in fuel use, reducing transport emissions in residential areas by 12%. 

Some environmental benefit from the change is expected from helping to unlock the potential for walking or cycling short distances instead of driving.

20mph speed limits are in force in an increasing number of towns and cities across Europe and the UK. Bristol, Edinburgh, Portsmouth and Oxford have citywide 20mph limits on many roads. Birmingham City Council have committed to introduce 20mph on all urban roads by 2025.  Nearly all London Boroughs have introduced a 20mph limit on roads that they control, along with TfL introducing 20mph speed limits on key ‘red route’ corridor routes across London.  The Welsh government are introducing a nationwide 20mph default speed limit in urban areas by 2024.  The UN and World Health Organisation have called for 20mph (30kph) speed limits on all urban roads to reduce the high rate of serious injuries and fatalities caused by road traffic collisions globally.

Large 20mph signs mark the entrance and exit of a 20mph area where the speed limit changes. These signs are supplemented by smaller repeater signs or road markings with speed limit roundels.

The change in speed limit will be a change to some driving habits and it will take some conscious decision making as a driver to make a difference. It may take some time to become second nature. In reality we are rarely driving at a consistent speed, particularly in a city where we are constantly accelerating, decelerating, and braking to respond to current traffic speeds, traffic lights or junctions, and other road users.

Our aim is to balance the needs of people driving with the safety and environment of local residents and all other road users. By reducing collisions and the severity and casualty impact of collisions, 20mph creates a safer environment for everyone, including people driving.  The consequences of being involved in a road traffic collision can be deeply traumatic for all involved, including drivers and passengers.  Driving at 20mph will reduce the risk of collisions and the severity of a collision when they happen, thus reducing the trauma associated with road traffic collisions for all those unfortunate to be involved in one.