Speed Management Interventions

Following the introduction of signs, repeaters and roundels when implementing 20 mph speed limits, if the desired reduction of speed is not being reached, speed management interventions can be considered.

Depending on the geographical area, the types and mix of road users, a mixture of interventions may be required to make speed management successful. Simple and sustainable road engineering measures such as lane-narrowing, refuge islands and medians are highly effective – especially for low to moderate speed environments in cities, towns, and villages. There are many interventions to reduce speeds and manage traffic as demonstrated in the City of Edinburgh Street Design Guidance

A mixture of examples are below:

Lane narrowing

Wider roads allow drivers to select higher travel speeds. This may be because the perceived margin for error is greater. So, narrower lane widths tend to slow traffic speeds  . Narrowing the roadway for vehicles will therefore assist speed reduction in a particular area. Even narrowing the perceived lane width can achieve slower speeds. This can be done with painted markings on the road.

Refuge islands and kerb extensions

Refuge islands and medians can provide a staged crossing point for pedestrians and simplifying decision-making. Kerb extensions can also improve pedestrian safety by reducing the crossing distance and the area and time in which pedestrians are at risk. This is particularly helpful for older or disabled pedestrians who may have difficulty choosing a safe gap in traffic at a crossing point. These interventions also result in narrower lanes, thereby contributing to lower speeds

Roundabouts

Roundabouts are effective in reducing the severity of crashes at an intersection because they require traffic to deviate from a straight path and therefore slow down to undertake the manoeuvre. The reduced speeds and direction of travel can result in reduced collision severity.

Repeater Signs

TSRGD 2016 removes the requirement for a minimum of one repeater sign to be placed within a 20 mph limit. It is for road authorities to decide how many repeater signs are needed and where they should be placed, taking cognisance of Chapter 3 of the Traffic Signs Manual ensuring there are sufficient repeater signs placed to inform road users of the speed limit in force.

Gateway treatments at entrances to towns and villages

Gateways are devices used to mark a threshold – usually to a village or higher risk location on the road – where lower speeds are required from drivers. Gateways rely on highly visible vertical treatments to capture driver/rider attention and usually include:

• large signs conveying the message that it is an entry to a location where pedestrians and other vulnerable road users are about to be encountered in greater numbers;
• pavement markings to narrow the perceived width of the carriageway, including painted central medians, for a short distance at least;
• large speed limit signs showing the lower speed limit that applies;
• other pavement markings to indicate clearly that a threshold is being crossed into a different environment;