High traffic speeds are arguably the largest contributor to traffic deaths in the United States. High speeds contribute to crash occurrence and their direct influence on impact speeds determine crash severities (Aarts and van Schagen, 2006; Hussain et al, 2018). Moreover, specific populations, i.e., traditionally marginalized and underserved communities, bear a disproportionate burden of the collective traffic injury problem (Hamann, Peek-Asa, and Butcher, 2020). Despite the existence of isolated interventions to curtail higher speeds—e.g., speed safety cameras, traffic calming road design, concordance between land use and road classifications—few of them have been widely and equitably adopted. None get at the deeply rooted and interconnected causes of the problem, such as people’s harried lifestyles, thrill-seeking behaviors, the consumption of increasingly more powerful vehicles, prioritizing speed over competing values of concern for self and others, among many other interacting factors.
To manage traffic speeds proactively and over longer periods of time, professionals need to recognize the complexity of this public health issue and to broaden their repertoire of ways to address it. Relevant here are cross-sectoral partnerships and tools to help teams of partners to visualize the complex processes that could be driving an outcome of interest (Arnold and Wade, 2015). To ultimately develop integrated strategies to managing travel speeds in various contexts, teams will need to draw upon traditional data (e.g., crashes, roadway inventory, traffic speed and volume data, freight transport) and less traditional data (e.g., indicators of land use density and mix; perceiving those who speed as “cool”; in-vehicle feedback on drivers’ travel speeds; consumer trends privileging vehicles of increasing size, weight, and horsepower; and workplace and social group “culture” and policies surrounding high travel speeds) to consider the interacting elements of the system that influence high travel speeds. These integrated strategies should also be adaptable enough to contend with disruptions that could impact travel speeds, such as global pandemics, siloed funding of disconnected parts of the system, increased awareness of social injustices and inequities in transportation safety and access, natural disasters, and technological breakthroughs.
As mentioned, there are several efficacious speed-reducing tools (e.g., speed safety cameras, traffic calming road design, and concordance between land use and road classifications), yet these are often not widely or equitably applied, and none address the complex array of reasons people drive at high speeds. For example, traffic calmed streets can reduce operating speeds, however, they fail to make people feel less hurried in their lives. This research would build upon a foundation of work focused on speed limit setting (e.g., NCHRP Research Report 966; NCHRP Project 17-79), street redesign, traffic signal coordination, and automated speed enforcement toward enhancing pedestrian safety (e.g., NCHRP Synthesis 535) to examine the confluence of factors that influence travel speeds. This research would bring to bear a package of promising practices (e.g., speed limit setting, land use, workplace, congestion pricing), transportation investments (e.g., transit provision, speed-oriented school, and workplace practices), communications strategies (e.g., media framing of travel speeds and traffic congestion), and interventions (e.g., intelligent speed adaptation (ISA), speed safety cameras and their equitable placement, operation, and re-investment schemes) that can be incorporated into a unified, adaptable framework for managing high travel speeds. The research should also shed light on strategies that do not work, or that may have unintended consequences to help free agencies from defaulting to costly and ineffectual schemes and to encourage working with partners to improve outcomes.
The research approach could include the following tasks:
1. Synthesize a broad literature on speed reduction strategies, as well as community-based injury reduction interventions.
2. Generate insights on speed-related dynamics (e.g., workplace practices that knowingly or unknowingly incentivize high travel speeds among employees), feedbacks (e.g., sprawling land uses that incite high speeds to cover increasing distances), and potential leverage points for intervention (e.g., incorporating safe design speeds in traffic impact assessment (TIA) procedures).
3. Incorporate strategies into a prototype Integrated Strategies for Speed Management Framework for managing high travel speeds in an integrated manner.
4. Design prospective demonstration studies with local, regional, and state partners on the implementation of the Integrated Strategies for Speed Management Framework. It is anticipated that this prospective demonstration study would seek guidance on best practices for identifying partners, policies, practices, and interventions that, when used in appropriate contexts and in combination, can help manage travel speeds across various spatial and time scales.