Portsmouth’s 20mph Scheme

The purpose of the scheme is to improve safety through Portsmouth’s residential streets and allow vehicles to drive at speeds appropriate to the conditions of the road without the pressure of other vehicles intimidating them to travel faster than they feel comfortable with.

Introducing a citywide 20mph limit enabled Portsmouth to use terminal and repeater signs as apposed to expensive engineering calming features such as speed cushions and build outs. There are more than 1,200 roads included in the scheme throughout Portsmouth.

Since July 1999 traffic authorities have had the powers to introduce 20 mph speed limits without obtaining the consent of the Secretary of State. This enabled Portsmouth City Council to implement a citywide 20mph limit across the residential roads in the council’s jurisdiction.

This was achieved by splitting the city into six sectors of roughly equal size to implement the scheme on a more manageable basis. The implementation included erecting gateway signs at the junctions of roads which were included in the scheme and roads that would remain 30mph. To comply with legislation, two signs were erected with the upper limit (in this case 30mph) and one sign with 20mph displayed. This was accompanied by 20 roundels painted at the junction and 300mm repeater signs that were attached to the lamp columns throughout the 20mph roads.

The scheme was completed in March 2008 and since then Portsmouth City Council has been working on the post scheme analysis which includes before and after speed analysis, and before and after KSI (Killed or Seriously Injured) data. This data has been produced into a report written by Atkins Consultancy on behalf of the Department for Transport which evaluates the implementation. One of the key findings from the report shows that vehicular speeds which were high have dropped considerably whereas there hasn’t been much change in speeds which were already low.

The council works alongside the emergency services to improve safety on the roads. Although a 20mph speed limit is self-enforcing due to the low speed, Portsmouth City Council and the Hampshire Constabulary work together to target specific roads that have a higher average speed.

This is achieved through education and enforcement days which work by the police giving any motorist caught speeding a choice of a fixed penalty notice and three points on their license, or to attend an education event carried out by Portsmouth City Council and Hampshire Fire & Rescue service. The education is through hard-hitting videos, practical demonstrations and talks. The average speed of roads that have been included on this programme have seen a slight drop.

There are many benefits of introducing a residential 20mph scheme that impact all users. Motorists feel safer travelling at appropriate speeds while cyclists can take advantage of contra-flow cycle lanes that have been implemented as a result of reducing the speed.

As part of the DfT report into the scheme a satisfaction survey was carried out for the residents of the city with the results showing that since implementation more children walk to school and more residents use their bikes.

Overall the 20mph scheme in Portsmouth has been a success and the majority of residents believe the scheme has benefited the city. There has been huge interest in the scheme from local authorities across the country as well as organisations carrying out events regarding the scheme. It is anticipated that more authorities will follow Portsmouth in creating a citywide 20mph limit across residential roads.