Evaluation of Automated License Plate Recognition for Improving British Columbia's Green Light Program
This analysis evaluates the marginal benefits of adding an automated license plate recognition system (APLRS) for commercial motor vehicles (CMVs) to the British Columbia Ministry of Transportation's (BCMOT) Green Light Transportation System (GLTS), which was launched in the spring of 2009. At the time of publication, GLTS was a voluntary program for CMVs to increase mobility by collecting data for CMVs at highway speeds using weigh-in-motion (WIM) and automatic vehicle identification (AVI) technologies. GLTS utilizes an in-vehicle transponder that electronically relays vehicle registration and other pertinent information to the inspection station as the vehicle approaches WIM scales. The GLTS allows vehicles that have been pre-screened to bypass physical inspection unless they are selected randomly for inspection. The APLRS functions similarly to the GLTS because it interfaces with the multiple databases for credentialing and enforcement purposes, but relies on photographing the front and rear license plates instead of using a transponder to relay information to the system.
Because of the voluntary nature of the GLTS program, the BCMOT estimate for penetration is approximately 15 percent in five years. Because the ALPRS system would not require registration of CMVs, penetration is at the level of accurate plate reading, which according to tests is nearly 90 percent, and can be achieved in a shorter period of time. However, the GLTS system transponders provide a stop/do not stop for inspection indication up to 15 minutes before the CMV arrives at an inspection station, while the ALPRS system would require high accuracy of information passed to CMV drivers through variable message signs (VMS) and drivers following those directions. The resulting conservatively estimated APLR penetration rate is 60 percent.
The authors estimate that the low penetration rate of 5 percent for GLTS in the first year would have minimal or no impact on the number of vehicles receiving out of service (OOS) orders, which was 27 percent in 2007. However, based on the capture rate of 60 to 88 percent for license plate data and a one day test project, the authors estimate that 57 percent would be a conservative estimate of the OOS rate, with less non-violation vehicles getting physically inspected. Along with OOS orders come $580 fines. The increase in the number of OOS orders issued due to ALPR technology would bring in an additional $1.13 million (CAN) beyond the $3.78 million (CAN) from GLTS.
Inspector Productivity & Efficiency
An increase in the OOS rate from 27 percent with GLTS to at least 57 percent with ALPR would increase inspector productivity at least 2.11 times. The ALPR technology also reduces inspector workload by reducing the number of CMVs required to pull into inspection stations. With the GLTS system, 97 percent of CMVs will still have to pull into inspection stations, but the sample ALPR project limited that to only 49 percent of CMVs. The number of vehicles that need to pull into the inspection stations would be reduced by 48 percent.
Vehicle Travel Time
A microscopic simulation was used to estimate CMV travel time savings, based on a 10 percent GLTS penetration rate and 60 percent ALPR penetration rate. Total travel time savings include both trucks that bypass the inspections, as well as trucks that do not bypass inspections, but benefit from reduced queue sizes at the stations. GLTS would save commercial vehicles 10,670 hours, while ALPR would save 54,863 hours for commercial vehicles. Based on the BCMOT's default value of $46.94 (CAN) per hour for value of time, the monetary savings would be $500,850 (CAN) and $2,575,259 (CAN) for GLTS and ALPR respectively.
Fuel Savings & Emissions Reductions
Based on the same simulation mentioned above, for three inspection stations, the GLTS and ALPR systems would save 109,291 and 588,279 liters (28,872 and 155,406 gallons) of fuel respectively. These fuel savings translate to emissions reductions of 308 and 1,657 metric tonnes, respectively.
Potential Reduction of Collisions
The estimated benefit of fewer collisions is the result of the higher OOS rate at inspection stations. With respect to injuries the model estimates a reduction is 69 and 145 collisions due to with GLTS and ALPR respectively. With respect to fatalities, the reduction is 5 and 9 respectively. The resulting number of fewer collisions translates to an estimated $7,372,000 (CAN) in injury costs and $16,680,000 (CAN) in fatality costs avoided when ALPR is used in addition to GLTS.