Strategy Behind the Standard
Pre-Greens (sometimes referred to as ‘cycle filter signals‘) provide cyclists with priority over motor traffic through an early release. A green cycle aspect can be used, either together with low level cycle signals (LLCS) or as an alternative, to provide cyclists with a few seconds head start before the main traffic flow. LLCS are generally used with an Advanced Stop Line (ASL), allowing cyclists to position themselves in front of the traffic queue and gain maximum advantage.

This enables cyclists to establish themselves within the junction ahead of the release of general traffic, in order to reduce the risk of potential conflicts between cyclists and turning traffic.

Best Practice Guidance to be used by Essex Highways
Cycle Infrastructure Design LTN 1/20 – Chapter 10.6.14
Cycle Infrastructure Design LTN 1/20 – Chapter 10.6.39 – Early Release

ECC Recommendations
At all signalised junction improvements, pre-greens should be considered.

How the Standard Should be Applied
The early release phase should be long enough to allow cyclists to travel beyond the left turn conflict point before other vehicles reach that point. Experience so far suggests an early start phase of 4 seconds gives cyclists good priority without unduly delaying traffic. Designers may start with this as a default value, but should confirm this is suitable through on-site observations once installed, and adjust if necessary.

A longer advance green time may tempt cyclists into turning right across oncoming traffic. An early start phase of less than 3 s is not recommended.

Green cycle aspects used should be in line with the TSRGD Diagram 3001.4.

Figure 1: TSRGD Diagram 3001.4 – Green cycle signal for inclusion in traffic light signals.

Examples of Best Practice

Queens St., York

Hills Rd, Cambridge