Red Light Camera Validation

Richard Garratt, Senior Transport Analyst at Leicestershire County Council gives an overview of the project below and how the PhaseT saved time and resources to provide accurate, convenient traffic data to the Council.

What is the RoadPod PhaseT?

The RoadPod® PhaseT uses the same core technology as MetroCount’s world-trusted traffic counters, with the addition of a fibre optical interface that records changing signal phases in parallel with individual vehicle data.

This provides vehicle volumes, classification, speed, direction, gap, headway and more, categorised into either the green, amber or red signal phase.

(Right: Example of data available from the RoadPod PhaseT).

Why is accuracy so important when monitoring signalised intersections?

“We received a request from the Department to review a local red light camera site,” shares Richard Garratt. “We had a number of pieces of equipment at our disposal but nothing to easily link the optical output of the traffic lights to pneumatic tube traffic data without being labour intensive to analyse. 

The team was also concerned about introducing minor timing discrepancies in a process that has very little margin for error without having an influence on the results.

We looked at a number of suppliers websites and found the RoadPod® PhaseT which looked to meet our needs.  We spoke to the MetroCount team who presented the capabilities, answering any questions we had.

After 15 years of using MetroCount systems to gather the County’s traffic counts and speed data, we knew we could rely on the RoadPod PhaseT to provide the validation required with high accuracy and minimal manual intervention.

The support from MetroCount has continued throughout the project from meeting onsite to assisting with the initial set-up, liaising with the signal engineer for the installation of the optical cable in the signal head and running through the processing of the data in the MTE software.”

Triple checking data accuracy

“We added a camera to validate a sample of the results and to further understand what the vehicles were doing at the location i.e.

• slightly overrunning the stop line,
• emergency vehicles running red/amber lights,
• rolling over the stop line as the adjacent signals change anticipating their new phase.”

Red Light Camera Validation Outcomes

“Since having the equipment we have discussed using it to monitor potential sites as well as existing ones and appreciate its other potential use linked to signals/timing and risk.”

“We were impressed with the accuracy and would suggest a similar approach to anyone interested in analysing signalised intersections.

Richard Garratt, Senior Transport Analyst at Leicestershire County Council

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