This year's UN Road Safety Week (17-23 May) under the theme "Streets for Life" calls to implement a maximum vehicular speed of 30 kilometres per hour in streets used by a mix of pedestrians and vehicles around residential, school and hospital areas. A large body of research carried out in different countries found that 30kmh speed limits play decisive roles in reducing road crashes, saving lives and preventing damage. More than 80 cities across the world have experienced reduced numbers of fatal road crashes as well as less automotive air pollution and traffic congestion after this speed limit was enforced.
The political economy of speed limits has many curious facets. The conventional economics or business-centric approach for road communication wants both the roads and vehicles to be equipped with features allowing for speed in order to add pace to the economy and raise turnover. While such an approach requires the application of finer and often costly technologies, an accumulating body of evidence identifies speed as a major factor for road crash casualties, bringing long term impact on families and the national economy as well, contrary to the expectation that speed will benefit the national economy.
Dhaka is among the cities with an alarming number of casualties from road crashes. In 2018, a fatal crash gave rise to a student movement after Abdul Karim Rajib and Dia Khanam Mim, both students of Shahid Ramij Uddin Cantonment College, died after being hit by a bus on Airport Road on July 29 that year. Students occupied the streets waging an unprecedented agitation, demanding an end to the issues plaguing the country's roads.
In Bangladesh, where thousands of lives are lost every year on the roads, the UN's call for speed management through the Stockholm Declaration (February 19-20, 2020) can play a crucial role if executed with commitment. The call is based on solid evidence, a summary of which is given here.
Low-speed streets save lives: In Tanzania, 30kmh has been shown to cut road injuries by as much as 26 percent and has now been expanded to 50 high-risk school areas. In Toronto, Canada, road crashes fell by 28 percent since speed limits were reduced from 40kmh to 30kmh in 2015. Colombian capital Bogota has introduced 30kmh zones in its speed management plan, reducing traffic fatalities by 32 percent. A study from London found that 20mph zones were associated with a 42 percent reduction in road casualties, while in Bristol the introduction of 20mph limits was associated with a 63 percent reduction in fatal injuries between 2008 and 2016.
The World Health Organisation concludes that an increase in average speed of one kilometre per hour results in a three percent higher risk of a crash and a four to five percent increase in fatalities. Studies find that when hit by a vehicle driven above 30kmh speed, pedestrians are at considerably greater risk of death, bringing even greater risk for the young and elderly.
People want lower speed where they live: Surveys from around the world consistently show that the majority of people agree that 30kmh is the correct speed limit for residential roads. Low-speed streets help reduce congestion and are widely popular. A recent global poll in 11 countries from the Child Health Initiative found that 74 percent of respondents supported speed restrictions on streets around schools.
There are also significant health benefits from slowing traffic, including less noise and a supportive shift to active lifestyles through walking and cycling. The social interactions that people have on the street are important for building collective wellbeing.
Thirty km per hour will not decrease journey times: Studies further show that higher speed does not much help reduce the journey time due to the time consumed at intersections and traffic signals. It is found that in most typical urban journeys, the time difference between driving at a maximum of 30kmh and 50kmh is minimal.
Low-speed streets are effective for any country in any context: Although many of the countries that have pioneered the effective road safety approaches are high income countries, low-speed streets are possible for any country to implement, irrespective of their level of development or number of vehicles. Thirty kilometres per hour zones have been successfully set in neighbourhoods in Africa, North America, Asia and Latin America.
Thirty km per hour increases vehicle emission but any impacts on pollution are low while the safety benefits are significant: The relation between speed and emissions is complex, particularly at low speeds. It depends on many factors, including vehicle type, temperature and road layout. However, in low-speed streets, vehicles tend to move more smoothly, with fewer accelerations and decelerations, leading to lower pollution. A recent study of 20mph zones in London found no net negative impact, and an earlier study of a 30kmh zone from Belgium revealed the same findings.
Safer streets ensured through lower speed encourage a shift from vehicle use to walking and cycling. And fewer vehicles will mean a reduction in air pollution and CO2 emissions as well as wider health benefits from increased physical activity.
A World Bank study in 2017 found seven km per hour as the average speed of vehicles in Dhaka—a drop from 21kmh a decade ago. Transport specialist Robert Gallahar found in his study in 2016, sponsored by BRAC and the Copenhagen Consensus Centre, that the public transport spending by the Bangladesh government under the revised Strategic Transport Plan (STP), including the metro rail, will only improve the traffic flow to 13.7 kmh. However, vehicles show a tendency to drive in high speed in the intervals between traffic congestions, often inviting fatal crashes. Similar tendencies of speed driving are seen in other cities, roads and highways also, ignoring the traffic signpost alerts about frequent pedestrian movement.
Implementing the UN mandated and tested 30kmh speed limit in Dhaka city warrants urgent consideration, particularly in the Transport Regulations currently under formulation by the Bangladesh government. Furthermore, this speed limit, if notified by the mayors of Dhaka North and Dhaka South City Corporations, and aided by adequate public awareness campaigns and enforced by the Dhaka Metropolitan Police, in all probability will be effective in reducing deaths, injuries and other damages from road crashes.
Najmul A Hussain is Director of the Road Safety Programme at BRAC.