Keeping the OCR Software on the Dulles Toll Road Up to Speed

In August 2017, TransCore selected Perceptics to provide optical character recognition (OCR) software for a Violation Enforcement System (VES) for the Dulles Toll Road (DTR) in Northern Virginia. The DTR is a commuter-based, 14-mile portion of Virginia Route 267, with four primary travel lanes in each direction. Perceptics provided two Fault-Tolerant OCR Servers–one primary and one backup–to process the estimated 14 million images per year captured by the VES.

The requirements detailed in the RFP issued by Metropolitan Washington Airports Authority (MWAA) were for an OCR system that would return correct OCR results on 80% of human readable plates including plate number, type, and jurisdiction for plates issued by 16 East Coast states.

The VES was designed to be scalable, adaptable, and capable of processing a higher volume of license plate images in the event the Authority transitioned to all electronic tolling in the future. In June 2022, MWAA announced it planned to make that transition to AET starting in January 2023.

The Challenge:

Perceptics’ OCR system had been meeting or exceeding the required specification of returning a correct OCR result on 80% of human readable images since the system was accepted in 2018. However, in late April 2022, TransCore discovered a change of license plate types was causing the OCR read rate to fall below spec.

As MWAA was in the process of evaluating the impact the transition to AET would have on the Agency, the need to bring the OCR read rates up was of even greater urgency than normal.

The Solution:

Following the notification in the dip in OCR performance from TransCore, Perceptics’ engineers immediately began the ground truthing process to create updated configuration files.

Ground truthing is a practice in which Perceptics’ experienced image reviewers validate the OCR interpretation of the images. This process teaches the system to recognize changes in license plates and new license plate designs. Once these reviewers examine a set of images and identify areas of potential improvement, Perceptics engineers upgrade the OCR software files.

Within days, new files were delivered to TransCore.

After TransCore engineers uploaded the new configuration files to the servers at Dulles Toll Road, they noticed the read rates were still slightly below specification. Perceptics performed another round of ground truthing and supplied new configuration files. Within just over four weeks, Perceptics and TransCore were able to once again exceed the OCR requirements set out by MWAA and provide them with accurate data with which to make informed decisions about their transition to AET.

If you want the ability to resolve issues quickly with a dedicated and experienced customer service team, reach out today for more information on switching your OCR to Perceptics.