Global Street Design Guide Defining Streets Safe Streets Save Lives

Global Street Design Guide

Safe Streets Save Lives

More than 1.2 million people die on roads around the world every year. That is equivalent to roughly one person dying every 30 seconds, or over 3,400 people dying every single day of the year.¹ Many of these deaths occur on urban roads and are preventable crashes caused by behavior induced by street design.

Creating safe streets is a critical responsibility shared by designers, engineers, regulators, and civic leaders. Even in the cities with the best safety records, the threat of traffic violence makes movement around the city a potentially dangerous daily activity. Highway-like street designs that prioritize automobiles over vulnerable users and encourage high speeds fail to provide safe environments.

A New Paradigm for Safety

The new paradigm for safety is built on human limits. The human body is fragile and can only survive certain forces. This means:

- Reducing exposure to the risk of conflict
- Reduce crash numbers and the severity of impact by
- Reducing speed
- Shaping streets that are safe for vulnerable users

When vehicles move at or below 40 km/h, potential conflicts take place at lower speeds, dramatically increasing the chances of survival in the case of a crash.

Studies from around the globe have shown that most traffic deaths, especially the easily preventable pedestrian deaths, occur on a small percentage of arterial streets.² These streets are rendered dangerous by design. They contain the following characteristics:

Wide streets that invite speeding and lack safe crossings.
Streets that act as front yards but allow aggressive behavior by those passing through.
Highway-like surface streets where motorcyclists and public transport passengers are at risk from large speed differentials, and where sidewalks are missing or substandard.

The combination of high traffic speeds and volumes, long crossings, and large distances between marked crossings make them fatal corridors for vulnerable users.

Speed is the single most important factor in the safety of a street, and is directly proportional to the risk of pedestrian fatality in cases of conflict.

The relationship between impact speed and risk of pedestrian death.
Several recent studies (Pasanen 1993, DETR 1998, Rosen and Sanders 2009, and Tefft 2011) show the existence of a clear relationship between vehicular speeds and pedestrian casualties, supporting the idea that speeds over 40 km/h should not be permitted in urban streets. However, most of these studies were conducted in high-income countries and there are reasons to believe this relationship might be even more extreme in low- and middle-income countries.³

The relationship between speed and stopping distance. The graphic above depicts minimum stopping distances, including perception, reaction, and braking times. They are based on dry conditions and assume perfect visibility.⁴

Common Causes of Traffic Fatalities

Many traffic injuries are directly related to design. Conditions become more dangerous with the addition of speed. Common causes for traffic fatalities include the following:

Lack of Sidewalks: When the sidewalk is blocked, narrow, or nonexistent, pedestrians are forced into the roadbed. This presents a particular threat when the street is designed for fast-moving vehicles, and not designed to accommodate all users safely.
Lack of Accessible Crossings: Pedestrians are at risk of being struck when accessible crossings are not provided or are inaccessible. Mid-block pedestrian crashes are very common on large streets, where vehicle volumes and speeds are prioritized over sufficient opportunities for safe crossing.
Lack of Protection: Wide, multi-lane streets without refuge spaces expose pedestrians to moving vehicles for longer distances as they cross the street. This is particularly unsafe for the elderly or those who move at a slower pace.
Lack of Predictability: When signals and countdown clocks are not provided, or when signal cycle lengths result in a long wait time, pedestrians are unable to safely judge the time they have and are more likely to cross unsafely.
Lack of Cycle Facilities: Cyclists are at risk of rear-end and overtaking crashes when mixing with motor vehicles at moderately high speeds, especially on multi-lane streets.
Poor Intersection Design: Large intersections are often designed for dangerous, high-speed turning. Lack of visibility results in poor navigation and assessment of different users’ movements.
Unsafe Boarding Areas: Transit riders are at risk when boarding and alighting vehicles in traffic, especially if no safe facilities are provided. Higher-speed streets and poor intersection design near boarding areas increase chances for severe crashes and put vulnerable users at risk.
Surface Hazards: Obstacles and surface degradation, including potholes, can present hazards to pedestrians and cyclists.

Safe Design Supports Education and Enforcement

Regulations and education are critical to creating a culture of safety. However, a street cannot be made safe if it has been designed to prevent people from making safe decisions. Most road safety agendas focus on reducing probability of human error through education and enforcement, without emphasizing the design of safe streets. Design can ensure that a crash or conflict caused by human error will be limited in its severity. The design of a street is often far outside the scope of a safety project, but it can have direct and indirect impact on the safety
of street users.

Vision Zero and Sustainable Safety Programs

The Vision Zero (initiated in Sweden) and Sustainable Safety (initiated in the Netherlands) programs are proactive safety programs being adopted by an increasing number of cities around the world. The premise of such programs is that loss of life is unacceptable, and their goal is preventing all serious road crashes. These initiatives place the burden of safety on the system design, not the road user. Innovative street designs that reduce speed, strict enforcement against traffic violations, legislative ordinances that lower speed limits, and public awareness campaigns have proven to be impactful strategies adopted by these programs.

According to the World Health Organization, over 3,400 people die on the world’s roads every day and tens of millions of people are injured or disabled every year. Children, pedestrians, cyclists, and older people are among the most vulnerable of road users.

Footnotes

^{1. World Health Organization, Road Traffic Injuries (Geneva: WHO, 2015).}

^{2. World Health Organization, Global status report on road safety (Geneva: WHO, 2015), 9.}

^{3. Ben Welle et al. Cities Safer by Design: Guidance and Examples to Promote Traffic Safety through Urban and Street Design (Washington, DC: World Resource Institute, 2015). Erik Rosén and Ulrich Sander, “Pedestrian fatality risk as a function of car impact speed,” Accident Analysis and Prevention 41, No. 3 (2009).}

^{4. “Stopping distances,” Department of Transport and Main Roads, Government of Queensland, accessed June 7, 2016, http://www.tmr.qld.gov.au/Safety/Driver-guide/Speeding/Stopping-distances.aspx.}

Adapted by Global Street Design Guide published by Island Press.

Global Designing Cities Initiative