Rethinking Traffic Conflicts Technique - a breakthrough for the field?

Fay Patterson

University of Adelaide, South Australia

This presentation was delivered at the 2021 Online Conference Series and until October 2022 is only available to registered delegates and Content Access Pass holders via Interchange. For information on accessing this and other presentations please review the Content Access Pass options.

ABSTRACT

The use of crash-based data in safety assessments is subject to a number of well-documented limitations. Traffic Conflicts Technique (TCT) proposes using traffic interactions as a surrogate for crashes, enabling many or most of these limitations to be overcome. A significant amount of work has been invested into the field over some fifty plus years, with papers appearing with regularity in all of the major traffic engineering and road safety journals.

But while conflict studies are used in some areas of road safety practice, no single indicator proposed for TCT has been found to capture all aspects of a traffic encounter. There is no agreed method for undertaking TCT studies, with different countries adopting different standardised approaches. Additionally, TCT does not apply to single-vehicle crashes and produces poor results for mixed traffic. Even within the standardised approaches, TCT has not been operationalised such that conflicts can be used as a surrogate for crashes without recourse to an historic crash record, which reintroduces many of the crash data issues. As such, the potential of TCT has not been realised.

Due to its long history, a firm theoretical framework has been developed for TCT. However, issues in TCT theory remain, notably about ‘conflict’, ‘severity’, whether and how conflict is related to collision, the role of evasive manoeuvres, and how indicators used in TCT relate to fundamental definitions. And while some studies have shown correlation between TCT indicators and crash risk, there is a high degree of inconsistency. TCT currently cannot be used to calculate crash risk independently of an historic crash record and a major aim of TCT has not been realised.

My recently examined doctoral thesis, “The Adverse Effects of Paradigm and Pragmatism on Road Safety”, re-considers TCT by deliberately excluding the existing theoretical framework and re-thinking TCT from first principles. The implications are potentially profound

Author

Fay Patterson | University of Adelaide

Fay Patterson is an experienced traffic engineer who has specialised in walking and cycling for over 20 years. She is well known and respected in Adelaide for her design skills, being responsible for a number of innovative cycle infrastructure designs as well as planning, design, road safety assessment and feasibility studies. Fay has been awarded both an Excellence Award and the Janet Brash Memorial Prize by the Australian Institute of Traffic Planning and Management for her work in transport planning for pedestrians and cyclists, while her research has informed Austroads and NSW RMS technical guidance. She is a previous convening committee member for the Australian Walking and Cycling Conference series, current member of CWANZ (Cycling and Walking Australia and New Zealand) and has recently been awarded a PhD from the University of Adelaide for a cross-disciplinary thesis in the areas of Social Sciences and Engineering.