The need for a scheme can be identified in a variety of ways. It may, for example, be a bad accident record or the concerns of residents that prompts an investigation. Sometimes the council adopts an area wide approach to traffic problems, for example, where there is a demand from several residential roads for speed humps. To deal with this, priority is given to the worst problems first.
Potential schemes are assessed against the following policies:
- to achieve safe movement by reducing accident levels
- to promote and accommodate the maintenance and improvement of public transport
- to restrain traffic and safeguard the environment
- to seek high levels of mobility for all groups of people, especially for those who may have some kind of disability
- to reduce the impact of commuter parking
- to improve pedestrian safety, accessibility and convenience
- to promote cycling
The council consults residents for their views before the introduction of any new traffic measures. In addition, many traffic measures require the publication of a formal notice in the newspapers. A three week period is allowed for objections to be received. Formal objections are considered, and schemes may then be redesigned before they are introduced. The council, as highway authority, is responsible for making any relevant traffic orders and introducing and maintaining the physical measures. Enforcement of traffic orders relating to the movement of vehicles is the responsibility of the police, with the exception of bus lane enforcement, which is the responsibility of the local authority. Enforcement of all parking and waiting restrictions is the responsibility of the local authority.
Components of schemes
A variety of measures are used within traffic schemes, some of these include:
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.
Chicanes and priority measures
Chicanes are intended to reduce traffic speed by reducing the available carriageway width throughout a short length.
Chicanes present a physical barrier to a vehicles path, thereby further reducing speed.
Priority measures or narrowings, narrow the road, frequently to provide a safe crossing point for pedestrians.
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.
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.
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.
These are an effective, self-enforcing, means of stopping all through traffic movements. Roads are usually closed by a barrier and may have an emergency 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 around. 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 are relatively well balanced.
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.
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, or kerb build out.
White carriageway markings
Carriageway markings are a cheap and cost effective way of reducing accidents. At junctions they indicate 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 not normally permitted on the approaches to roundabouts. SLOW markings are often used on the approach to a hazard.
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 brows 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.
There are a number of grades of priority junction throughout the city. Some junctions in residential areas may have no form of priority road marking.
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 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.
For further information about traffic schemes within the city, contact the Road Safety Team:
- E-mail: email@example.com