Alternative Work Zone Intrusion Alarm (WZIA) Systems in California Range in Cost from $4,630 to $11,100 per Half-Mile.

State Evaluation Report Examines Work Zone Safety.

Made Public Date

A work zone intrusion alarm (WZIA) system was tested to improve the safety of the current Caltrans Standard Plans for traffic control in work zones in Sacramento, California. The objective of this study was to evaluate the effectiveness of four WZIA systems and readiness for deployment in California work zones. The pilot testing took place at the Caltrans Maintenance Equipment Training Academy (META) testing facility in November 2018. The testing consisted of a trip hose used for vehicle detection, an alarm unit attached to the vehicle, and Personal Safety Devices (PSDs) for work zone workers. In this pilot, data and information were collected and documented to evaluate sound level and distance, operation, and functional characteristics. In addition, worker reaction time depending on vehicle speed when it passed the trip hose was studied.

he WAS system cost was estimated on a hypothetical half-mile closure which included ten PSDs, three alarm units, six 33-foot trip hoses with chargers, and a single hand-held remote trigger. The exact cost of the Intellicone system was assumed from the insurance value of the system during shipping by the manufacturer because it is not currently in the market for purchase. The cost of the SonoBlaster system included the cost of only one CO2 cartridge per SonoBlaster unit. The number of SonoBlaster and Intellicone units required for a hypothetical half-mile closure were both assumed to be 63. Intellicone’s is in addition to two PSA units. The costs of work zone intrusion alarm systems are listed in Table 1. It is worth noting that the cost difference should be considered in view of the different level of coverage and safety features offered by each system.

Table 1: WZIA Cost Estimation Based on a Hypothetical Half-Mile Closure

Work Zone Intrusion Alarm System


Worker Alert System (WAS)






System Cost

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