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06 Apr 2021

California’s Experience with TACS Shows the Benefits go Beyond Tire Safety

Tom Der-VP ITS Solutions & Engineering
 Tom Der
Vice President, ITS Solutions & Engineering

When the State of California implemented IRD’s tire safety screening technology at their Cordelia enforcement facility, they got more than they expected from the system – identifying not only tire violations but other safety issues and violations as well.

Cordelia is one of 54 Commercial Vehicle Enforcement Facilities (CVEF) operated by the California Highway Patrol (CHP). Strategically located in the Bay Area’s busiest commercial corridor on Interstate 80, Cordelia runs 24/7 – 365 days/year. It is California’s first full implementation of e-screening from ramp to ramp. The project was a joint effort between CHP, Caltrans (California’s state DOT), and the County of Solano.

For Cordelia, IRD supplied a complex commercial vehicle screening system that uses high-technology solutions including Weigh-In-Motion (WIM), tire safety screening, machine vision, and automated database lookups. The technology at the site enables fast processing of commercial vehicles by sorting vehicles into different lanes at the weigh station based on the degree to which they meet inspection criteria. WIM and tire screening identify vehicles with potential weight and tire condition violations, while database screening identifies vehicles with safety or credential issues. The control system and software also offer a high degree of automation while ensuring transparency of operations and availability of manual overrides for crisis scenarios.

An unexpected benefit of adopting tire screening at the CVEF is that an increased incidence of out-of-service (OOS) violations related to non-tire-related safety issues was observed by CHP.

Weigh-In-Motion preclearance for efficiency and safety

With over 40,000 vehicles a year being inspected at Cordelia, screening technology plays an important role in optimizing resources. Preclearance ensures that time is not wasted on the static weighing of compliant vehicles and that the route does not become congested.

The Cordelia system was designed with highly accurate WIM, surpassing the ASTM Type III specifications typically required for most pre-clearance operations. The double-threshold SLC WIM scales on the ramp approaching the inspection station achieve accuracies of ±4% GVW for 95% of vehicles.

Tire safety screening

Tire safety screening is performed by IRD’s Tire Anomaly and Classification System (TACS™) which measures tire footprints using an array of sensors and identifies vehicles that have underinflated, flat, mismatched, or missing tires. Vehicles flagged by TACS or flagged as overweight by WIM on the ramp are identified as such in the vehicle records displayed through the operator software. Information sent to the operator's display from the pre-screening can also be sent to an inspector's terminal in the inspection bays.

TACS - Tire Anomaly and Classification System - Tire Safety Screening - Cordelia California
Tire anomaly screening using IRD TACS™ – Cordelia, California

The site incorporates iSINC® electronics to provide WIM screening and control other devices at the site. Vehicles are identified on the ramp using license plate and DOT Number reading cameras equipped with Optical Character Recognition (OCR). Cameras at the site also capture images of CVSA decals to screen for valid/expired inspection decals.

Credential and safety database screening

An Intelligent Roadside Operations Computer (iROC) enables rapid screening of identified vehicles against FMCSA and SAFER data sources for credential and safety screening. The iROC communicates with the iSINC® while also connecting with remote databases to enable screening for compliance with SAFER, intra-state vehicles, permit and tax violations. The iROC provides a data store for future analysis of commercial vehicle operations, something that may become a factor for future trend analysis of volumes and types of violations identified by the system.

Cordelia, California E-Screening Array - Cameras, WIM, Overheight Detection
E-screening array at Cordelia, California

Post-screening WIM system

Based on vehicle compliance, all commercial vehicles are directed into either the left or right lane. From these two lanes, they are sorted into one of the four low-speed WIM lanes downstream. Vehicles suspected of being non-compliant are directed to the two lanes closest to the station, whereas vehicles more likely to be compliant are directed to the two lanes to the left. All commercial vehicles are weighed again in the low-speed WIM lanes.

Cordelia, California Weigh In Motion (WIM) Lanes
Weigh-In-Motion (WIM) lane overview at the Cordelia weigh station

In the low-speed lanes, vehicles travel at 2-15 mph (3-24 kph) with double-threshold SLC WIM scales achieving accuracies of ±2%. Weight compliance is determined and signaled to a Programmable Logic Controller (PLC) that interprets iSINC® sign decisions to direct the flow of vehicles through the station using signs and signals. The PLC also plays an important role in backup detection and management. When it is determined that a vehicle is compliant, the system sets traffic signals directing the vehicle to leave the station. Non-compliant vehicles are held and directed by a station operator to an inspection bay or static scale for inspection.

Operator Software

IRD’s operator display software was customized to suit the Cordelia sorter system and site layout. The software displays commercial vehicle traffic entering the station, including potential weight and credential violations, and maintains a historical record of each vehicle that has passed through the station. Importantly, the system allows authorized inspection staff to adjust screening settings.

Outcome – TACS benefits exceeded expectations

The most important consideration for CHP is that commercial vehicles which travel through the Cordelia site will not pose a safety risk to the public. CHP inspectors closely examine vehicles that have been flagged by the e-screening system. The increase in tire violations identified in pre-screening since implementing TACS has provided significant added value through identifying out-of-service tire violations. The first six months of TACS saw a 30% increase in tire violations over the previous five-year average. As a percent of tire violations, TACS-identified violations included 39% of under-inflated tire violations and 62% of mismatched duals violations.

The identification of tire anomalies alone provides tremendous value, but in a recent Innovative Technology Deployment (ITD) Program Managers call, CHP revealed that vehicles with identified tire issues also tended to present with other violations at higher than typical rates. They tallied other types of commercial vehicle safety issues/violations found from TACS violation pull-ins and found that between January 1, 2020, and November 30, 2020, they accounted for:

  • 38% of general unsafe vehicle violations
  • 35% of single axle overweight violations
  • 29% of general maintenance violations
  • 20% of leaking brake hose violations
  • 18% of driving out of class violations
  • 17% of minimum tread depth violations
  • 17% of tandem axle overweight violations
  • 15% of worn brake hose violations
  • 13% of excessive oil/grease violations
  • 12% of kinked brake hose violations.
  • 12% of safety chain on towed vehicles violations
  • 11% of CA vehicle registration violations
  • 11% of general brake system violations
  • 11% of applied air loss violations
  • 9% of unapplied air loss violations
  • 8% of defective lighting violations
  • 6% of expired CA motor carrier permit violations

Indications, so far, are that those violation percentages will likely stay the same or not vary much.

California’s experience has shown that tire anomalies are correlated with other violations. This not only shows the value of adding tire safety screening to preclearance, it indicates that, even on its own, TACS also reveals significant numbers of safety violations that warrant OOS citations.


For more information on IRD’s tire screening, e-screening, and other automated commercial vehicle inspection technologies contact info@irdinc.com.

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