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Traffic Calming

20mph Zones and Speed Management

A major worry for pedestrians and cyclists is the speed of passing traffic. In some areas this is made worse by narrow or non-existent pavements which make the traffic seem too fast even if it isn't exceeding the speed limit.  As the severity of accidents increases in direct relation to vehicle speeds, a programme of speed reduction and rationalization is programmed for the city.  In order to reinforce low speed zones the following features can be expected to be encountered:

Gateway features

Designed to emphasise to drivers that they are entering an area where the needs of the local community are at least as important as the convenience of through traffic. They include things like:

• Red road surfacing with roundels
• Structures on the road verge such as gates or post and rail fences
• 20mph signs
• Countdown markers
• A central refuge
• Specially designed school signs

Build Outs and Chicanes

Build outs often narrow the road down to one carriageway – and make drivers slow down to drive through them as well as offering pedestrians space to see round parked cars. In a chicane, the road is narrowed on one side and then the other – drivers have to slow down to get round them.

Mini Roundabouts

Often used as part of traffic calming/speed reduction schemes. They are designed to make drivers slow down to go round them and to force them to look out for other vehicles entering the junction.

Coloured Road Surfacing

Coloured surface dressing that highlights traffic calmed features or used as part of a ‘Gateway’ treatment. A variety of colours can be used which visually segregates the road space. It is a cost effective measure which increases awareness of road/area conditions and enhances bus and cycle lanes.

Traffic Islands

Stop drivers overtaking other vehicles. Not very effective as a speed reduction measure on their own (2-3 mph reduction) but better as part of a more comprehensive scheme. Can be useful in providing pedestrian crossing facilities if correctly positioned. Can also help to enforce lane discipline.

Speed Humps

These force vehicles to slow down, since driving over them fast is very uncomfortable.

Speed Cushions

These are like speed humps but do not extend across the entire road. They are designed to be wide enough to slow down cars but not too wide to affect buses and emergency vehicles. They are usually installed in pairs arranged across the carriageway, but single cushions are sometimes put centrally between build outs. 'Three abreast' versions, and double pair arrangements have also been used.

Raised Tables

A raised table is a traffic calming feature that is placed across junctions in order to slow vehicle speeds – it raises and enhances the junction. This discourages through traffic and reduces vehicle speeds. The road appearance can be enhanced with discomfort being minimal at slow speeds.

20mph zones

Research has shown that the risk of a child being involved in an accident has reduced by about two-thirds where 20mph zones and speed limits have been installed. They can also help to protect the mobility impaired and other vulnerable road users including cyclists.  Consultation with resident within a proposed 20mph zone is paramount. In Portsmouth each area is considered for it's nature and a programme of consultation is developed. In ideal cases the residents are able to work with the engineering officers in designing a scheme which will be acceptable to all who live in an area and improve their environment as well as improve road safety.

Safer Routes to School Markings

Increasing driver awareness through the installation of road markings and signage in order to highlight an area surrounding a school. A variety of features can be implemented reducing vehicle speeds.
In Portsmouth, the Road Safety and Traffic Management Team are continually designing school safety zones as part of the Safer Routes to School Project. School safety zones already implemented in Portsmouth include: Allaway Avenue (for King Richard Secondary School, Westfield Junior School, and Saxon Shore Infant School), Fawcett Road (for Priory School), and Solent and Evelegh Road (for Solent Infant and Junior Schools).