Sophisticated software is used to predict the future impact that general growth or increased flows generated by a specific development will have on the highway network.

This software assists in identifying locations at which alterations are required to improve or maintain the flow of traffic and are usually introduced before predicted flows reach the point at which delays will be experienced.

Recognised methods that are considered where additional capacity is required on the highway network are:

  • Construction of additional lanes approaching a junction.
  • Installation of traffic signals.
  • Introduction of a priority controlled roundabout.
  • Installation of traffic signals on an existing roundabout.
  • Grade separation.

Traffic signals are installed for a number of different reasons including:

  • To allow the opportunity for minor roads with apparent flows to enter or cross heavy main roads.
  • A requirement for controlled pedestrian or cycle crossing facilities.
  • To control and assist safe traffic movements where visibility is restricted.
  • To reduce traffic related casualties at a site.
  • To accommodate a change/increase in traffic associated with an adjacent development.

It is our intention to use modes of operation such as MOVA, SCOOT and VA which are responsive to live traffic flows. These modes respond to vehicles approaching signals and provide a green signal to the necessary approach.

At different times of day or at sites that are not yet capable of running the modes of operation mentioned above the signals may run ‘fixed time plans' which is useful to operate on a number of closely situated junctions so that they can be be co-ordinated. This would usually run at peak times at sites when flows are predictable.

Alternatively, there may be a vehicle detector fault on the other approach causing it to call an approach unnecessarily and ‘extend’ the green time. This will be more noticeable at night or during the early hours of the morning.

These are known as right turn indicative arrows and are programmed to appear only when there is a sufficient queue of right turning vehicles waiting on a sensor loop in the road to trigger their appearance.

Junctions with this arrangement should be negotiated like any other junction, for example right turning vehicles should move forward of the stop line waiting in the junction for an adequate gap to appear in the opposing traffic.

If the green arrow does not appear and the lights turn to red there will be sufficient time complete the right turn manoeuvre if the stop line has been crossed.

The green man period is purely your invitation to cross at the crossing and is not meant to be long enough to complete the crossing manoeuvre. Depending on the type of crossing, time is given to allow you to clear before traffic gets a green. For example, the flashing green man at a pelican crossing gives ample time to clear.