Connecting Transportation Operations and Safety in Arizona

NHTSA · 2023 · ROSA P / United States. Department of Transportation. Federal Highway Administration. Office of Operations

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Summary

This case study examines how the Arizona Department of Transportation (ADOT) and the Maricopa Association of Governments (MAG) integrate transportation operations and safety to improve roadway reliability and reduce crashes. Motivated by ADOT’s vision to become the nation’s most reliable transportation system and its commitment to the "Toward Zero Deaths" initiative, the agency sought to move beyond traditional highway expansion toward operations-focused improvements. The primary objective was to institutionalize a connection between safety and mobility, ensuring that operational strategies enhance safety outcomes and vice versa. The study details ADOT’s organizational and procedural methods for achieving this integration. In 2015, ADOT reorganized its structure by creating a Transportation System Management and Operations (TSMO) Division that houses both safety and operations functions, including traffic engineering, incident management, and intelligent transportation systems (ITS). This division utilizes the Arizona Management System, incorporating Lean and Six Sigma techniques, to foster continuous improvement and mutual problem-solving. ADOT also employs a data-driven approach, overlaying crash data with traffic volume, speed, and incident data to identify high-risk bottlenecks. Furthermore, the agency’s Planning to Programming (P2P) process mandates a safety score for nearly all projects, ensuring safety is a primary criterion in project prioritization and funding eligibility, particularly for the Highway Safety Improvement Program. The paper highlights several specific operational strategies implemented to combine safety and mobility. Adaptive ramp metering on State Route 51 increased traffic flow by 152 vehicles per hour per lane and raised average speeds by 4.8 mph, while reducing delay costs by over $1 million annually. A dust detection and warning system on Interstate 10 uses variable speed limits to mitigate risks during sudden dust storms, addressing a historical cause of 40 fatalities. Additionally, a wrong-way driver detection system using thermal cameras has identified over 45 wrong-way vehicles, allowing for rapid law enforcement response and self-correction. An Incident Response Unit has responded to over 10,400 incidents in its first year, improving clearance times and reducing secondary crashes. MAG and local cities like Peoria and Tempe also integrate these disciplines through joint planning, traffic signal optimization, and the use of video analytics for near-miss detection. The significance of this approach lies in the demonstrated benefits of institutionalizing the link between operations and safety. By combining these functions within a single division and using integrated data and planning processes, ADOT has achieved greater safety, improved mobility, and more efficient resource utilization. The case study concludes that this coordinated structure facilitates timely identification of needs, streamlines project advancement, and ensures that operational designs do not compromise safety. This model serves as an example for other agencies seeking to align operational efficiency with the critical goal of reducing roadway fatalities and serious injuries.

Key finding

Integrating safety and operations functions within a single organizational division and coordinating planning processes enables transportation agencies to effectively combine mobility and safety objectives, resulting in improved road safety and operational efficiency.

Methodology

review

Provenance

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• regulatory evaluation

Information type

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• Applied Guidance: countermeasure evaluation
• Empirical Findings: crash risk outcomes
• Methodological Resource: dataset resource