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Purpose – Urban and suburban arterials carry a large share of urban traffic and contend with a relatively large proportion of transport network crashes. Road crashes and their consequent societal costs diminish the sustainability of transportation systems, highlighting the need to identify road safety problems and their corresponding solutions. This chapter briefly outlines problems and solutions associated with crash risk on urban and suburban arterials. In addition, this chapter studies and discusses several safety countermeasures – ranging from local treatments to integral frameworks – and their effectiveness on improving traffic safety of urban and suburban arterials.

Approach – Crash occurrence on urban and suburban arterials is affected by numerous contributing factors. This chapter pays attention primarily to the effects of traffic characteristics and road design features. In this regard, several pertinent variables which have been extensively examined in the literature are reviewed and their contributions to the safety of urban and suburban arterials are discussed.

Findings – A review of the literature identifies a number of variables as influential factors of crashes on urban and suburban arterials. Although the associations of some variables (e.g., traffic volume) are consistent with expectations, others (e.g., lane width and speed) show mixed and sometimes counterintuitive results. These findings signify that additional research is needed to reveal the correct functional form and magnitude of these relationships.

Practical implications – The results show that while the general direction and magnitude of effects of some engineering and management-related treatments are known, additional research is needed to consolidate the impact and effectiveness of integrated approaches.

Purpose – This chapter provides details of research that attempts to relate traffic operational conditions on uninterrupted flow facilities (e.g., freeways and expressways) with real-time crash likelihood. Unlike incident detection, the purpose of this line of work is to proactively assess crash likelihood and potentially reduce the likelihood through proactive traffic management techniques, including variable speed limit and ramp metering among others.

Methodology – The chapter distinguishes between the traditional aggregate crash frequency-based approach to safety evaluation and the approach needed for real-time crash risk estimation. Key references from the literature are summarised in terms of the reported effect of different traffic characteristics that can be derived in near real-time, including average speed, temporal variation in speed, volume and lane-occupancy, on crash occurrence.

Findings – Traffic and weather parameters are among the real-time crash-contributing factors. Among the most significant traffic parameters is speed particularly in the form of coefficient of variation of speed.

Research implications – In the traffic safety field, traditional data sources are infrastructure-based traffic detection systems. In the future, if automatic traffic detection systems could provide reliable data at the vehicle level, new variables such as headway could be introduced. Transferability of real-time crash prediction models is also of interest. Also, the potential effects of different management strategies to reduce real-time crash risk could be evaluated in a simulation environment.

Practical implications – This line of research has been at the forefront of bringing data mining and other machine-learning techniques into the traffic management arena. We expect these analysis techniques to play a more important role in real-time traffic management, not just for safety evaluation but also for congestion pricing and alternate routing.

Our commitment to the goal of zero traffic fatalities and serious injuries requires consideration of innovative traffic safety thinking. There is growing recognition that this goal requires a change in our culture as it relates to traffic safety (traffic safety culture). And yet, there is no consensus about a definition for traffic safety culture, no explicit theory-based model to predict the effect of traffic safety culture, and no practical guidance for applying these models to develop effective culture-based strategies. This chapter seeks to address these omissions from both an academic and practitioner perspective.

This chapter proposes a standard definition of traffic safety culture based on a model that integrates relevant theories of willful and intentional behavior. Importantly, a set of 10 principles are identified that provide the context and foundation from which the definition and model are derived. An understanding of these principles provides the logic and purpose for developing strategies that can transform traffic safety culture:

• (1)

  Traffic crashes are a significant public health concern.

• (2)

  Most traffic crashes are caused by human behavior, not the roadway, vehicle, or environment (e.g., weather).

• (3)

  Human behavior is influenced by beliefs.

• (4)

  Beliefs develop based on experience (actual and vicarious) and socialization.

• (5)

  Socialization is the process whereby an individual develops beliefs which align with the culture of a group with which the individual identifies (social identity).

• (6)

  Individuals can form an identity with many different groups in their social environment, each with a different degree of bonding.

• (7)

  A stronger bond results in greater conformity and motivation to abide with the group culture.

• (8)

  The shared beliefs of a group that affect behaviors related to traffic safety are called traffic safety culture.

• (9)

  The traffic safety culture of a group emerges from actions taken by stakeholders across the social ecology.

• (10)

  Traffic safety culture strategies increase actions by stakeholders across the social ecology to improve traffic safety culture among various groups.

Traffic crashes are a significant public health concern.

Most traffic crashes are caused by human behavior, not the roadway, vehicle, or environment (e.g., weather).

Human behavior is influenced by beliefs.

Beliefs develop based on experience (actual and vicarious) and socialization.

Socialization is the process whereby an individual develops beliefs which align with the culture of a group with which the individual identifies (social identity).

Individuals can form an identity with many different groups in their social environment, each with a different degree of bonding.

A stronger bond results in greater conformity and motivation to abide with the group culture.

The shared beliefs of a group that affect behaviors related to traffic safety are called traffic safety culture.

The traffic safety culture of a group emerges from actions taken by stakeholders across the social ecology.

Traffic safety culture strategies increase actions by stakeholders across the social ecology to improve traffic safety culture among various groups.

For the academic, these principles can also serve as hypotheses that can be explored to expand our knowledge about traffic safety culture. For the practitioner, these principles represent the basic logic and impetus for transforming traffic safety culture. By effectively communicating these principles and their connecting logic, we can express the importance of traffic safety culture and the need for supporting resources with other stakeholders.