Infrastructure designs and traffic safety: the road to vision zero

This volume presents studies which have focused on the impact of infrastructure designs. This includes evaluating the impact of roundabouts in Ghana, spatial analysis of traffic crashes in three different locations – Galle, Sri Lanka, Shanghai, China and Moshi, Tanzania. The authors have applied geo spatial techniques to identify high crash locations and focus on the local built environment features contributing to Road traffic crashes.

I am encouraged to report these studies. These studies show the interest amongst the researchers in investigating the impact of infrastructure designs on traffic crashes. This is in contrast to earlier emphasis on legislations, education and enforcement strategies in Low- and Middle-Income countries (LMICs) to improve traffic safety. A recent study (Staton et al., 2016) published a systematic review and a meta summary of effectiveness of road traffic injury measures in LMICs. The study included a search of 8560 articles and out of that 18 met all the inclusion criteria. More than 90% of studies selected by the authors to evaluate the effectiveness of legislation and educational strategies reflects the safety focus in these countries. This also implies that standards used for designing and constructing roads will ensure safety, therefore, only appropriate legislation regarding seat belt use, speed limits and alcohol control are required to improve traffic safety in LMICs. We must question the lack of interest and efforts to investigate safety impact of alternate design features on road user behaviour and traffic safety.

Bawa and Damesere-Derry present an evaluation of traffic crashes at recently implemented roundabouts in Kumasi, Ghana. The study reported slight increase in traffic crashes on one of the round-about and noted to revisit the designs to improve safety performance. In recent years, large number of studies have shown the benefit of round-about in reducing fatal crashes. Roundabouts have also been recommended in place of signalized junctions by researchers who promote vision zero. Perhaps in mixed traffic conditions as prevailing in Kumasi, Ghana further research is required to improve the designs of roundabouts rather than abandoning them for signalized junctions which do not meet the principles of vision zero.

Besharati and Kashani have applied clustering and association rules technique to explain pedestrian crashes in Iran. The study reports increased fatality risk in locations having poor illumination and increased risk of being hit by trucks along vacant land or agriculture fields. Clearly the presence of pedestrians on highways poses a major challenge in terms of design an appropriate speed adaptation by vehicles. Strategies such as driver training and telling people not to jaywalk have been proven to be very ineffective in inducing safety behaviour.

Spatial analysis techniques to understand the pattern of high risk locations have been applied by De Silva, Thannda, Vissoci et al. in Galle, Sri Lanka. The analysis is based on the crash information available from police records. Similarly Chen, Huang, Zhu and Jin have applied Network Kernel Density techniques to investigate hotspots of Road traffic Crashes in Shanghai. Waldon, Mnibaga, Vissoci et al. have presented hot spot analysis in Moshi Tanzania. All three studies show the strength of spatial techniques in identifying the spots which require further attention in terms of conducting safety audit for improving infrastructure shortcomings. The researchers must understand the short comings of police data and exercise caution in suggesting recommendations based on ‘cause’ of traffic crash listed in the police records.

Kim and Park from Korea Research Institute for Human Settlements have investigated safety features of freeway weaving segments with a buffer separated HOV lane. The results are counterintuitive-weaving segments with an access points tend to show lower crash rates. The authors have recommended further research.

Getting counterintuitive results in traffic safety research is not uncommon. In last three decades several researchers have discussed the application of systems theory to traffic safety to explain some of the counter intuitive results. Systems theory facilitates in structuring a complex reality. Researchers have highlighted that a decomposition in elements, components, aspects and relations provides oversight and coherence across levels and entities that interact with each other. Putting events in the context of systems in which they operate, requires a distinction between event and system, similar to a patient and the health system or a convict and the judicial system. While accidents should be prevented for the sake of their unacceptable consequences, the object of research for safety interventions is at the systems level (ESReDA 2009; Stoop, 2015).

Perrow (1984) has discussed some fundamental properties of complex systems in terms of tight and loose coupling between different elements and non-linear interactions between elements, and therefore, the need for building systems which do not depend on user or operator alone to ensure safety. Traffic crashes present an excellent example of complex systems, uncertainties and nonlinear interactions between human beings, vehicles and the road environment. This makes a strong case for moving away from focusing on the errors that road users make to concentrating on road and vehicle designs that can reduce the propensity and severity of crashes. Safety science has had a major influence on the traffic safety theories in the last 50 years.

Many traffic safety theories can be explained based on the engineering and behavioural theories. For instance, drivers can modify their behaviour based on what they see on the road ahead of them (e.g. increasing speed or reducing attention), especially when the lower risk is brought about by a road design countermeasure (Assum, Bjørnskau, Fosser, & Sagberg, 1999). Physiological theory may be related to both engineering and behavioural theory to some extent. For instance it was suggested that drivers are more likely to fall asleep or feel bored on straight, monotonous, dual carriageway roads with little traffic (Sagberg, 1999). In this case, drivers changed their behaviour on certain types of road (e.g. straight and monotonous roads); and on the other hand, road engineers could alter the road environment in order to reduce driver boredom.

It is in this context that the studies focusing on impact of built environment features and infrastructure design features on road user behaviour and traffic safety acquire utmost importance.

As we move towards the next phase of decade of safety action from 2020 to 2030, traditional interventions dealing with reducing relatively high risks are in the process of coming to the end of their life cycle, suggesting that they may be subject to the law of diminishing returns. Realization of vision zero requires generation of new knowledge and establishing a process which enables generation of new knowledge to ensure safe transport systems in LMICs. Given the complexity of traffic safety science and its implementation in field, continuous experimentation is required in LMICs to develop safe highways based on the principles of safe systems approach. We invite young researchers to meet this challenge.