According to worldwide estimates, more than 50% of the global population are currently living in urban areas, and by 2050, this figure will rise to 68%, i.e., more than two-thirds of the global population [1
]. Trends in world population growth and distribution may play an essential role in achieving the United Nations’ Sustainable Development Goals, which aim to achieve decent lives on a healthy planet for all by 2030, while balancing the three dimensions of sustainable development: economic, social and environmental [2
In many countries, rise in urban density is accompanied by a growing use of public transport as a mobility mode [3
]. For example, a 2017 report [4
], using data from 39 countries, indicated an evolution in urban mobility patterns over the last decade, i.e., growth in the modal share of public transport, together with other sustainable modes like walking and cycling, and, complementing this trend, a marked decrease in car use. Moreover, urban mobility choices were strongly linked to density, with a higher propensity to travel by public transport observed in more densely populated areas. In line with recent developments, current policies for sustainable urban mobility focus on promoting public transport, walking and cycling [5
Ideally, public transportation should provide an efficient and equitable alternative for urban mobility, with associated benefits such as reduced traffic congestion, lower emissions and gains in individual and public health due to active travel [6
]. An equitable alternative implies that public transportation should ensure that all population segments and road users receive fair treatment, i.e., that transport facilities and services accommodate all users, including those with special needs, and that benefits are shared and no one is left behind [9
In addition, macro-evaluations suggest that public transport is a safer form of transportation compared with car travel. For example, in the European Union, only 3% of total road fatalities were observed in crashes involving buses and coaches [12
]. Estimates in terms of fatalities or serious injuries per billion person-kilometers travelled showed a substantially lower risk for a bus passenger than for a car occupant in the USA [13
], several European countries [14
], and in Israel [15
]. Moreover, studies showed that when public transit travel increases in a particular community, traffic casualty rates tend to decline. For example, Stimpson et al. [16
] analyzed traffic data for 100 U.S. cities over 29 years and found that increased use of mass transit was associated with fewer fatalities from road crashes after accounting for climate and the economic costs of driving. Similarly, Litman [13
] showed that U.S. cities with more annual transit trips per capita had a lower traffic fatality rate.
As the urban population and traffic grow, local and national governments in various countries frequently address the objective scarcity of space for traffic in urban areas by using bus priority systems to improve mobility and promote public transport use [17
]. Forms of bus priority systems include bus routes, bus priority lanes and Bus Rapid Transit (BRT). A bus route is a facility designed to physically separate public transport paths from general traffic lanes, so that a higher commercial speed is made possible, e.g., [18
]. Bus priority lanes allow a broader range of road layout strategies (e.g., curbside, median-side, etc.) and traffic management solutions (e.g., full-time vs. part-time, exclusive vs. mixed use, etc.). Physical separation from other lanes can be introduced, as well as some forms of signal priority at intersections. A BRT is the ultimate form of bus priority: it is an integrated system combining infrastructure facilities for the exclusive use of buses together with elements of an intelligent management system and services such as centralized operation control, off-board fare collection and level boarding [20
]. Arguably the most famous example of BRT in Curitiba, Brazil, but various forms of bus priority systems can be currently found in several South American countries, as well as in India, Turkey, Australia, China, USA and European countries [18
Regardless of their form, extensive evidence has shown that bus priority routes (BPRs) reduce passenger travel time and improve the reliability and attractiveness of public transport [21
]. However, less research has been dedicated to the road safety implications of such systems [25
], while available evidence of their safety impacts is limited and less consistent, sometimes indicating crash increases, particularly in terms of pedestrian crashes.
1.1. Previous Research Findings on the Safety Impacts of BPRs
Several studies have estimated the general safety impacts of BPR systems. For example, Bocarejo et al. [31
] found an overall reduction in injury crashes along the bus corridors in Bogota following the implementation of the TransMilenio BRT system, to the extent of 48–60%, compared with a 39% reduction in injury crashes in the whole city (as a comparison-group). However, an increase in crashes was observed around some areas, e.g., in the vicinity of stations, which was apparently related to the higher flows of pedestrians. Duduta et al. [20
] re-evaluated the data collected by other studies and reported positive impacts of BPR implementation on the safety levels of urban roads in South American countries and India, while in some cases, e.g., Belo Horizonte in Brazil and Delhi in India, an increase in crashes was observed. The summary evaluations of these cases showed that pedestrian injury was one of the major safety problems in BPR operation since pedestrians were involved in only 7% of the total crashes but represented over half of the fatalities from the bus routes [25
Goh et al. [26
] modeled bus crashes in Metropolitan Melbourne, Australia, based on the data of a large bus company and found that street segments with bus priority lanes were associated with a lower crash frequency relative to those without dedicated bus lanes. In a complementary study based on police records, Goh et al. [32
] found that the implementation of bus priority lanes in the city was associated with a 14% crash reduction on streets where BPRs were present. In another study, Goh et al. [33
] compared traffic conflict patterns in bus priority lanes with mixed traffic conditions and showed that bus lanes reduced conflict occurrences at intersection approaches and bus stop locations. Evidently, bus priority acts to remove bus movements from the general traffic flow and provides new and separate road space for bus traffic, thus reducing crash potential.
Studies of tram priority lanes in Melbourne [34
] also reported associated crash reductions, yet, an increase in the probability of fatal crashes was found for road sections with tram priorities compared with roads without the priority lanes. The latter was explained by higher speeds in sections with priority lanes, which increased the crash severity in a collision with other road users and, especially, pedestrians. Furthermore, Naznin et al. [36
] studied the safety effects of tram priority on 23 arterials in Melbourne, using before–after comparisons, and found a statistically significant adjusted crash reduction rate of 19.4% after the implementation of lane priority measures.
A study conducted in the metropolitan areas of Pittsburgh and Philadelphia examined the impact of non-isolated bus routes on the frequency of all crashes along road segments [37
]. It found that the presence of bus routes along roadway segments, i.e., bus lines in mixed traffic, increased the average crash frequency by 27% per year compared with segments with no bus line presence, thus leaving room for the positive safety potential of (separated) BPRs.
Tse et al. [27
] estimated the safety impacts of bus priority lanes in Hong Kong, showing decreasing trends in crashes involving public transport vehicles (with mean values of 17–21%) but increasing trends in other vehicle crashes (with mean values of 5–20%). More detailed evaluations in this and other studies [20
] showed that most crashes on streets with BPRs occurred outside the dedicated bus lanes. Hence, BPRs’ safety is a matter of their impact on general vehicle traffic and pedestrian safety, whereas infrastructure design solutions may be of high importance.
In particular, BPR configurations may have an impact on crash occurrences. The main forms of BPR configurations, as opposed to conventional mixed traffic, are center-lane/median busways, curbside bus lanes and counter-flow bus lanes. Using data on crashes involving pedestrians and vehicles of BPR systems in several South American cities, Duduta et al. [25
] found that center-lane configurations were safer compared with curbside systems, while counter-flow bus lanes were the least safe. In addition, the detailed models indicated [25
] that a higher number of lanes for general traffic and a higher number of legs at the intersections on bus routes were associated with higher crash figures. Duduta et al. [20
] investigated the effects of the introduction of median BPRs in three cities in Mexico, Columbia and India, highlighting a reduction in total crashes, as well as those with fatalities and injuries, compared with figures from the cities as a whole. However, the positive effects in these cases might well be related to an overall improvement in the urban road infrastructure that accompanied the systems’ construction, since basic urban infrastructure in developing countries is quite unsafe [38
In Israel, signalized intersections with median BPRs were characterized by higher figures of total and severe crashes and crashes involving pedestrians, relative to comparison sites where BPR was not present, when controlling for other road characteristics [39
In a study carried out in Hong Kong [27
], the safety impacts of curbside BPRs were estimated, but most results were not statistically significant. Chen et al. [40
] examined the safety impacts of curbside BPRs introduced in New York city and found significant increases in vehicle, pedestrian and all crashes, having controlled for changes in comparison-group sites.
A number of studies examined the safety impacts of signal priority measures for bus or tram traffic at intersections but reported mixed results. Shahla et al. [41
] modeled the relationships between transit facilities’ characteristics and road traffic crashes in Toronto, Canada, and found that the existence of transit signal priority was associated with a crash increase at signalized intersections, both in crashes involving buses/trams and in all crashes (an addition of 25–51%). In contrast, studies conducted in Melbourne reported crash reductions in before–after comparisons following the introduction of signal priority measures for bus or tram traffic [26
]; for example, the expected crash frequency lowered by 11.1% when bus signal priority was implemented at intersections [32
], and there was a reduction rate of 13.9% with tram signal priority [36
]. Song and Noyce [42
] carried out before–after analyses of data from eleven bus transit corridors in King County, Washington, and found reductions in corridor-level crashes with the implementation of bus signal priority, e.g., a 13% reduction in total crashes and a 5% reduction in fatal and injury crashes.
It should be noted in this context that BPR implementation is typically associated with tangible changes in urban infrastructure and traffic, thereby imposing additional demands on road user behavior and especially on pedestrians. Summaries of international experiences provide recommendations for how to integrate safety into the design and operation of bus routes [18
]. They usually emphasize the need for physical separation of the bus lanes, highlighting them by using a different aggregate color, fencing BRT street segments when applicable, and providing signalized intersections only, in order to reduce interactions between buses and other vehicles and prevent uncontrolled pedestrian crossings along the bus routes [39
In Israel over the past two decades, noticeable efforts have been undertaken to adopt the international recommendations for infrastructure design, as applied to the new BPRs. Despite efforts to reduce safety risks, BPR introduction has sometimes resulted in an increase in pedestrian crash figures [39
]. Higher crash frequencies can be attributed to the higher complexity of traffic settings on streets with BPRs, as opposed to regular urban roads and particularly at junctions, as BPRs create more complex crossing configurations and longer waiting times for crossing pedestrians.
1.2. The Current Study Motivation
Previous studies indicate that BPR operation has mixed effects on road safety and that further empirical research is needed to enrich knowledge on the relationship between BPR design and crash occurrences. Pedestrian safety is especially important in this context, since BPRs are intended to increase public transport use and, hence, to attract more pedestrians. In addition, in Israel, the development of BPRs is one of the main policies encouraged today by the Ministry of Transport. Currently, certain BPRs are available in the major cities of Tel Aviv, Jerusalem and Haifa. In the coming years, a rapid development of public transport is expected in many more cities, with ongoing planning for hundreds of BPR kilometers. Therefore, examining design and safety aspects of such systems is crucial in order to understand and address the risks that BPR systems may present.
Being aware of the discrepancy in international research findings and the importance of local context, this study was initiated to examine the safety impacts of the BPRs that have been implemented in Israel over the last decades. Such formal evaluations were not performed in the past, except for one study that examined crash changes on BRT routes in Haifa during the first two years of operation [43
]. The current study applied longer time periods than [43
] and also considered BPR safety impacts in additional cities. This study contributes to the literature by showing that, in general, negative safety impacts of BPRs can be expected on busy urban roads, yet the extent of the impact differs depending on BPR configurations. The current study compares three BPR configurations: curbside bus lanes, center-lane bus routes near two lanes for general traffic, and center-lane bus routes near a single traffic lane, indicating that the center-lane bus routes have less harmful safety impacts relative to the curbside. Moreover, center-lane bus routes adjacent to a single traffic lane appear to be most promising in moderating crash increases following BPR introduction on urban roads.
The remainder of the paper is structured as follows. Section 2
describes the study framework, data and methods. Section 3
shows the evaluation results. Section 4
provides a general discussion of the study’s findings in the context of international research and their implications for planning bus priority routes. Section 5
presents the main conclusions for local urban planners.