Back in the 1980’s, the Greater London Council (which would become London Regional Transport in 1984 and then Transport for London in 2000) had it’s own plan for “smoothing traffic flow”, the introduction of a flashing amber arrow to light controller intersections.

In mainland Europe, many countries traffic rules allow for a combined vehicle turn and pedestrian crossing phase, where vehicles have to yield to pedestrians if there are any using the crossing. This allows for a shorter traffic light cycle, improved crossing times for pedestrians, and enables provision for separate cycle path flow not to be disrupted by the turning of motor vehicles.

In the UK we have a strict separation of pedestrian and motor traffic light phases, the green man on pedestrian crossings guarantees to pedestrians that there will be no conflict with motor traffic. Meaning that to signalise crossings for pedestrians, turning traffic either needs it’s own turning lane that can be individually controlled or an all way red light and green man phase is required. Not ideal for efficiency.

This is also a major problem for the provision of separate cycleways as it makes it impossible to provide a straight ahead cycleway in the same phase as vehicles due to the conflict with vehicles turning left unless a dedicated left turn lane is provided, an option which is often difficult in the limited space of the urban streetscape.

A typical light controlled crossroad might look something like this:

Pedestrians are given lots of room but have to wait a long time for the crossings. If central islands were provided as often they are, then the waiting time is doubled in the name of traffic flow. How might this look if we redistribute the road space in ways you see in Holland:

We’ve simplified the driving lanes, introducing predictability about where traffic will be going and removing the jostling for position that occurs when you have multiple straight ahead lanes (aka stacking). We’ve also added safe space for cyclists away from motor traffic at the junction, as well as resolved cyclist/pedestrian conflicts by providing a safe island for pedestrians to wait in for the crossing lights.

The problem comes with the left turns of motor traffic, they cut straight through the pedestrian and cyclist routes. In many countries, the road markings would be enough to provide pedestrians with safe passage, but even though the highway code ensures it in the UK, drivers are not used to giving way to pedestrians when shown a green light. The solution is to introduce the amber flashing filter arrow.

170: Take extra care at junctions. You should:

Watch out for pedestrians crossing a road into which you are turning. If they have started to cross they have priority, so give way.

Away from the junction on the more major (east/west) road, we’ve moved the cyclists from between the traffic and the parked cars, to between the parked cars and the pedestrians, and on the minor (north/south) road we provide a way for them to move from the road to the cycle path and back again.

So how does the amber arrow make this possible? Let’s look at the light phases in the following animation:

Phase 1: The main road has the green light. All traffic (motor, cycle and pedestrian) can flow east/west without hindrance. Right turning traffic is held at a red light and left turning motor traffic is shown a flashing amber light and must give way to cycles and pedestrians.

Phase 2: Right turns for motor traffic from the main road get the green light while all other directions are held at red. Cyclists and pedestrians can still turn left but are also held at red for going straight ahead and to the right.

Phase 3: The minor road has the green light, again all traffic can flow north/south with right turns limited by a red light and left turns given a flashing amber light.

Phase 4: Finally the right turns from the minor road get the green light. If right turns are limited by design, then cyclists and pedestrians can be given the green light for turning right in the remaining direction.

Without the amber arrow, a dedicated pedestrian and cyclist phase would be required, causing delays for all traffic in all directions (and making cyclists more likely to want to use the more efficient motor traffic lanes).

Alternatively, if traffic volume is suitably low, a Dutch style roundabout could be used instead without any change to current traffic law:

So is it time that we introduced what has been proved to work in many other European countries (including Ireland)?