In an earlier article (May 2017), I stated that traffic calming seems to me to be the most effective strategy that we can use to protect one of our most vulnerable road user groups: children. The intention then was to have a follow up article but this was overtaken by events and I had to write about Regulation 250. I would therefore like to revisit the issue of traffic calming and put forward a case for accelerating the implementation of traffic calming on local streets across urban areas in South Africa. One often hears of the need to keep children off the streets as a way of keeping them safe. This is understandable given the high traffic danger and high number of crimes against children currently being experienced in South Africa. However, in my opinion this is an unfortunate sentiment given the already limited opportunity for both outdoor play and independent mobility by children nowadays. Instead of striving to keep children away from the streets, we should rather be reclaiming our local streets through traffic calming so that they become safe places for our children to play and walk.
This is informed by the fact that most crash fatalities occur in residential neighbourhoods (a fact sometimes masked by the high media coverage given to crashes that occur on the higher-order roads) and I believe this is where our greatest focus should be with regard to road safety improvements. The main caveats obviously are that firstly everyone (including communities) should be aware that traffic calming is not the panacea to all problems (for indeed it has to be complimented by other measures) and secondly that if not well thought-out, traffic calming (particularly spot treatments as opposed to area-wide schemes) can generate opposition from residents of neighbouring areas who may fear that the traffic problems of one area will spill over into their streets.
What is traffic calming and why promote it so much
According to Litman (1999)[1], traffic calming is the name for road design strategies to reduce vehicle speeds and volume. Both vehicular volume and speed have an impact on the vulnerability of children to road crashes. Generally higher volumes and higher speed entail higher traffic risk for children and other pedestrians. Traffic calming programmes may be reactive or proactive[2] with the former responding to citizen requests for action (e.g. through resident petitions) while the latter involves staff identifying problems (e.g. through crash mapping or local area analysis) and initiating action. The former approach can however be problematic because communities sometimes unrealistically view traffic calming as the panacea to all their traffic problems. With this caveat in mind, resident petitions do allow communities and other interested role players to be proactive regarding traffic calming.
As stated by Ewing (1999), a traffic calming programme may make spot improvements, street by street, or it may plan and implement improvements on an area-wide basis, with multiple streets treated at the same time. Traffic calming forms the first E of the 3 Es of any good traffic safety programme: Engineering (the other being Education and Enforcement). While the other two Es are important, I feel that the engineering aspect goes a long way in reducing child road deaths and injuries. This is informed by two main factors, namely: the vulnerability of children to road traffic crashes as well as the relationship between vehicular speed and crash severity. These two factors are discussed in some greater detail below.
- Vulnerability of children to crashes
According to the World Health Organisation (WHO) road traffic injuries are the leading cause of death among 15-19 year olds and the second leading cause among 5-14 year olds. This makes children one of the most vulnerable. This vulnerability emanates from two main reasons namely:
- Small physical size
- Undeveloped skills or abilities for dealing with traffic situations
With regard to child pedestrian skills, the following five factors have been identified as limiting child pedestrian skills:[3]
- Young children may lack the physical ability to cross the street within normal signal times, and their short stature limits their visibility to drivers in conditions that may be fine for adults
- Children are likely to choose the shortest route, rather than the safest route, across streets, often darting out mid-block or entering the roadway between parked cars
- Children normally disregard peripheral vision, have reduced attentiveness, localise sounds poorly and lack sufficient impulse control
- Young children do not evaluate potential traffic threats effectively. They cannot anticipate driver behaviour, have less acute sensory perception, and process information more slowly than adults
- Children may engage in ‘magical thinking’ that leads them to believe, for example that they are protected within the confines of a painted crosswalk
We can acknowledge the reality of children’s limited pedestrian skills by making our roads more forgiving of children’s ‘mistakes’ on the road. We can use education to teach road safety to children and they take it to heart however this might be of little help when a car comes hurtling towards them at 80km/h on a local road. We can improve on enforcement but municipalities only have so many dedicated traffic police officers and the reality is that we cannot have a traffic officer on each section of our roads. It is therefore imperative to have measures that force drivers to slow down, particularly on the local roads where children share the road with vehicular traffic.
2. Relationship between speed and probability of death
A second compelling reason is the relationship between speed and crash severity as shown in the first graph below. Reducing speed therefore increases chances of pedestrians surviving a crash and traffic calming has been proven to be an effective tool of reducing speed. For instance, studies reported in Litman (1999) indicated reductions in vehicle accident rates because of traffic calming as shown in the second graph below.
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| The graph illustrates that the probability that a pedestrian will be killed by a motor vehicle increases dramatically with speed. It indicates that while most vulnerable road users survive if hit by a car travelling at 30km/h, the majority are killed if hit by a car travelling at 60km/h | This figure illustrates changes in vehicle accident rates from traffic calming programs reported in fifteen international studies, indicating that most show significant reductions. The vertical axis shows % Reported Reduction in Accidents Due to Traffic calming |
What are the engineering options?
- Speed control measures
- Vertical deflection which entail raising a portion of a road surface to create discomfort for drivers travelling at high speed. Examples of vertical deflection include: speed bumps, speed tables, raised crosswalks, raised intersections and rumble strips
- Horizontal deflection meant to make vehicles swerve slightly thereby forcing drivers to slow down. These include: traffic circles, roundabouts, chicanes
- Horizontal narrowing e.g. neckdowns, centre island narrowing, chokers, ‘road diets’ and bike lanes
- Speed limits, warning signs
- Volume measures
These include among others measures the following:
- Full closure of certain streets or street sections
- Half closure
- Median barriers etc
Potential downside of traffic calming
Admittedly, traffic calming can have some unintended negative impacts including: higher fuel consumption, increased noise and air pollution due to increased stops and use of lower gears as well as impacts over the wider area not covered by a traffic calming scheme. However, in my opinion the benefits to communities in the form of lives saved far outweigh the inconvenience to motorists. What is clear to me is that most of our local streets need to be retrofitted with traffic calming measures to make them safer for children. As put across neatly in a report by the Bronx Safe Routes to School Programme, the idea behind traffic calming is that neighbourhood streets we walk with our children are part of our everyday lives and should be shared with, but not exploited by motorists who often use them as speed ways and short cuts.
Notes
[1] Litman, T. 1999: Traffic calming: benefits, costs and equity impacts. Victoria Transport Policy Institute (VTPI) 7 December 1999
[2] Ewing R. 1999: Traffic calming: State of the practice, FHWA-RD-99-135, Institute of Transportation Engineers, Washington.
[3] The Centre for Disease Control 1996
[4] Global Road Safety Partnership 2008: Speed management: A road safety manual for decision-makers and practitioners,
