Back in May 2020, C&T Technology installed a trial of the Iteris VersiCam™ video traffic detector camera on a busy junction of the A38 Gloucester Road in Bristol. The aim was to replace a failed SCOOT detector and to make a long-term performance analysis, under a range of conditions.  Our Blog in July last year detailed the installation scenario and presented initial positive evidence that the VersiCam™ traffic detector was an effective replacement for a conventional SCOOT Loop system. As a new or repaired SCOOT detector would have required expensive, invasive and disruptive roadworks on a main arterial road into Bristol, the council were keen to investigate longer term performance of the video detector.

Five months later, the team at Bristol City Council carried out a manual count to assess the performance of the VersiCam™ in wet and twilight/dusky conditions. They concluded that the result had not changed since the initial installation, having found no-faults or glitches. 

Now at seven months, a further performance assessment, this time in night-time conditions, has delivered equally positive results. Following a manual count comparison test by Bristol Traffic Control Service’s Principal UTMC Engineer, Jackie Davies and her team, the VersiCam™ continues to deliver excellent performance.

VersiCam™ 7-Month Assessment Findings

The manual count results in dark conditions are detailed in the table below. The photograph illustrates the lighting conditions. The data was shown to be comparable with the equivalent positive count assessments in Wet/Twilight conditions in October and Sunny conditions shortly after the initial installation June.

VersiCam video traffic detector in Dark/Twilight Dec2020
Bristol Versicam traffic detector

The manual counts were found to be only very slightly different than the count site based on the detector.  A few discrepancies found included:

  • A parked car just upstream of the stop-line for a few minutes during the second segment of the count, which caused some of the vehicles to be passing through the junction in lane 2, so they were not in the detection zone.
  • There was some exit blocking (again due to parking issues) which caused vehicles to bunch together, reducing the headway between vehicles to less than 2m at some points. In this case, the detector was unable see the ‘gap’ between the vehicles.  

For comparison, it was concluded that neither of these discrepancies presented an issue as both incidents would have also occured with a conventional Loop detector.

The SCOOT detector was also checked for the time against the count site and the LPU conversion rate was very close, within 95% difference, with 354 vehicles counted via the SCOOT’s LPU conversion.

Previous VersiCam™ Assessment Data

* Detected 1 pedestrian
**Site exit blocked by downstream roadworks, so a lot of queuing

VersiCam traffic detector performance, Sunny/Dry, June2020

Our Case Study about the Bristol VersiCam™ trial can be found here

If you are interested in finding out more about the VersiCam™ video systems as a replacement for SCOOT Loop detection, please contact Chris Webb at C&T Technology on: 0161 443 4163 or email: