Traffic Management Schemes
Many traffic measures require the publication of a formal Notice. A three week period is allowed for objections to be received. Formal objections are considered, and schemes may need to be re-designed with further Notices being published, before a legally enforceable Traffic Order can be made and the scheme introduced. The Council, as Highway Authority, is responsible for introducing and maintaining the physical measures and for making any necessary Traffic Orders but with the exception of parking schemes, enforcement of Traffic Orders is the responsibility of Police.
Components of Schemes
There is no single solution to problems associated with traffic management. A variety of measures are used sometimes in combination.
Speed Control Humps
There is usually opposition from the Emergency Services and Bus Companies to the use of speed control humps. The Emergency Services object because humps increase their attendance times for emergency calls, and thus the risk to lives and property. The Ambulance Service and Bus Companies object because of the discomfort and possible injury that may be caused to their passengers and the increased wear and tear on vehicles, particularly buses going over speed tables every day.
There are regulations governing the layout of speed control humps. There must be a form of "slowing feature" - usually formed by a change of priority (traffic entering the system has to turn sharp left or right into the road, or has to "give way". Sometimes mini roundabouts are used at the start of a system of humps.
The shape of speed humps is strictly regulated. They must be 50mm to 100mm high, at least 2.75m long and extend over the full width of the road, except for a drainage channel at either end. They may have either flat or round tops.
Many local authorities have adopted the 75mm high hump as a standard. This is because it has been found to reduce traffic to around 22 mph. The 100 mm high humps reduce speeds to 17 mph on the hump but speeds rise to 35 mph between the humps, causing excessive acceleration, braking and increased pollution. Flat topped humps can be of any length and are often known as "speed tables". They are sometimes used to reduce the impact on long wheel base vehicles such as buses.
Speed control humps can lead to complaints of increased noise and vibration from traffic. They have however been proved to reduce traffic speed and have been installed in many locations.
"Pillow" or "Cushion" Humps
These are a form of speed control hump which are wide enough to allow a wide wheelbase vehicle to pass unhindered. Buses or a fire engines are not affected by them, whereas a smaller wheelbase vehicle, such as a car, would have to have at least one set of wheels on the hump. Thus cars are slowed, whereas other traffic is generally unaffected. These are intended to overcome the objections of the Emergency Services and Bus Companies.
They make possible speed reduction measures in roads that would otherwise not have them introduced.
"Chicanes" and "Throttles"
Chicanes and throttles are intended to reduce traffic speed by reducing the available carriageway width throughout a short length.
Chicanes introduce a physical deflection into the vehicles' horizontal path, thereby further reducing the vehicle speed.
Throttles narrow the road, frequently to provide a safe crossing point for pedestrians, sometimes in conjunction with a speed table.
Kerb Build Outs
At some road junctions visibility is often reduced because of the shape of the road or because of parked cars. Building out the kerb into the carriageway can help solve this problem. It provides protection for motorists emerging from a side road as they can safely pull further out to see, and be seen. Pedestrians are similarly protected, have more space to stand and can also see and be seen better. Cars are forced to park further from a junction or crossing point.
Width restriction are a self enforcing means of restricting access for large vehicles. Posts or bollards are placed in the road about 2.1 metres (7 feet) apart, such that vehicles wider than this cannot pass between them. There must be an alternative route available for large vehicles such as refuse collection vehicles and this sometimes limits their application in residential areas.
Sometimes a gate is provided for use of fire engines and other emergency vehicles. The gate is kept locked but emergency vehicles carry keys.
Many residents mistakenly ask for width restrictions to be introduced as a means of slowing down traffic. Width restrictions do not, and are not intended to, reduce traffic speed.
One Way Streets, Banned Turns and No Entry
These help control traffic movements, without completely restricting access. They can stop commuter "rat-runs" which occur.
One-way working may be for the whole length of a street, or in a short length at one end - a one-way plug.
A suitable alternative route must be identified and available for traffic travelling in the opposite direction to the one-way street, or for traffic needing to turn in the direction of the ban. This alternative would not normally be via a residential road.
One-way streets often lead to an increase in traffic speed. Short lengths are difficult to enforce if drivers are irresponsible and determined enough to drive against the one-way. This is dangerous and illegal.
Some residents find one-way streets and banned movements inconvenient as they may result in reduced levels access to their homes.
These are an effective, self-enforcing, means of stopping all through traffic movements. Roads are usually closed by a barrier with an emergency access gate for Police, Fire and Ambulance vehicles.
Near to a road closure, it is necessary to make provision, on either side, for large vehicles to turn round. That is why it is not used in many residential areas. It may also be inconvenient to some residents as Road Closures limit access.
Standard roundabouts are intended to assist at a junction where there is a heavy right turning movement. They work best where traffic flows on each arm are reasonably well balanced and they allow traffic to flow comparatively freely.
Mini roundabouts are introduced both as a means of reducing accidents, by slowing traffic, and to assist right turning movements. Their advantage over full size roundabouts is that they can often be accommodated within the existing road space, without expensive road widening.
As at a full size roundabout, the rule at a mini roundabout is "give way to traffic from the right".
The Council installs or upgrades several pedestrian crossings, (ie. zebra or signalled crossings) each year. Requests are often made by residents and each is examined on its individual merits. Many requests are not justified because of low levels of pedestrian movement.
The following factors are taken into consideration in assessing the need for a crossing :
- The record personal injury accidents involving pedestrians
- The volumes of vehicular and pedestrian traffic and the potential for conflict between pedestrians and vehicles
- The difficulty that pedestrians face from traffic speed and volumes
- The length of time pedestrians have to wait before they can cross
- Proximity of locations which attract pedestrian activity through the day , eg. proximity to stations
Pedestrian crossing do have shortcomings and are not the answer in every cases. Motorists who use the road regularly tend to ignore crossings if not often used. Similarly pedestrians can rely on the crossing and, rather than watching the traffic, assume that, because a "green man" is showing, the traffic will stop. Both of these problems can result in an increased risk to pedestrians rather than a decreased risk.
- Pelican Crossings
These signalled crossings are used on roads which have high traffic volumes, high traffic approach speeds or very high pedestrian flows. The time allocated for pedestrian crossing movement is dictated by DETR's guidelines and is based upon the width of the road.
- Zebra Crossings
These are used on roads of less importance, with lower pedestrian or traffic flows.
- Traffic Islands/Pedestrian Refuges
Where a formal pedestrian crossing is not justified these can be installed. They assist pedestrians by letting them cross the road in two stages. The restriction to the use of this measure is the width of the carriageway. It must be at least 7.8m wide to allow for the island and two lanes of traffic.
Facilities for the Disabled
Tactile paving is now used at all new zebra and pelican crossings to help people with impaired vision. Similar tactile paving is also used at many ramped crossing points. Many single pelican crossings have audible signals, as well as the green man signal, to indicate when it is safe to cross the road.
Some staggered two stage pelican crossings and some junction signals are fitted with a tactile knob on the pedestrian push-buttons, rather than an audible signal. This is so that visually impaired people can tell which part of the staggered crossing or junction is safe to cross.
- Junction Entry Treatments
A junction entry treatment is placed across the carriageway of the minor road at a road junction. The object is to show motorists that they are leaving a main road and entering a residential area and to raise the priority for pedestrians crossing the junction. This treatment often has a speed table, kerb build out and gateway features.
- White Carriageway Markings
Carriageway markings are a cheap and cost effective way of reducing accidents. At junctions they provide an indication of priorities, and as centre or lane lines, they indicate the best line for vehicles to follow. White markings are generally advisory.
Lane arrows are used on the approaches to traffic signalled junctions to indicate which lane should be used for turning and straight ahead movements. Lane arrows are generally not permitted on the approaches to roundabouts. SLOW markings are often used on the approach to a hazard.
Areas of central cross hatching, commonly called "ghost island" markings, are useful as a means of reducing accidents by separating on-coming traffic, reducing traffic speed and providing safe right turning areas. These, along with central traffic islands, have been shown to play a major part in reducing motor cycle accidents.
- Continuous White Lines
Continuous white centre line markings must not be crossed and are generally used to prevent overtaking and reduce speeds in roads with poor visibility due to bends or the crests of hills. These are also used sparingly so that they are more effective and have more impact when they are used. There are criteria for the introduction of these markings based upon the speed of traffic and the visibility distances.
It is also an offence to park in any section of road that is marked with a continuous white line. Continuous white lines may only be crossed by traffic that is turning right
- Road Junctions
There are a number of grades of Priority Junction throughout the Borough. Some junctions in residential areas may have no form of priority road marking. However, wherever possible, these are being marked under ongoing maintenance and upgrading programmes to show which arm of the junction should give way.
Other junctions may have a "give way" line, "give way line and triangle marking" "give way line, a triangle marking and a give way sign"
Some junctions may have a "Stop" sign and marking. These are used infrequently, in order to ensure that they have more impact on motorists. There are strict criteria, relating to visibility distances of approaching traffic, which must be met before "Stop" signs can be introduced.
- Traffic Signals and Control
Traffic signals are designed to optimise and control traffic at a junction by sharing out the time to different arms of the junction and to pedestrians. Traffic signals do not always solve accident problems.
Last Updated: 30 November 2017