Can firefighters and traffic safety advocates find a safe street width?
The City of Austin is contemplating raising the minimum street width from 20 ft. (which matches the International Fire Code) to 25 ft. at the request of the Austin Fire Department (AFT). There will be a community meeting on this issue September 17, 2018. To learn more about how street widths influence fire and traffic injury risk, dig into this report produced by the Los Angeles Public Health Department in 2013.
We’re in a trendy, well-lit micro-brewery in the college town of San Marcos, about halfway between Austin and San Antonio on the edge of the Texas hill country. Fire Chief Les Stephens has agreed to a public, informal debate on ideal road widths with his friend and colleague Matt Lewis, who for five years was the Director of Planning and Development for San Marcos.
Chief Stephens argues in favor of wider traffic lanes to fit his fire department’s trucks so they can respond to emergencies more quickly, and with the right equipment.
“While you’ve been talking, another person has died in a crash,” rebuts Lewis, referring to the far higher frequency of fatal crashes compared to fatal fires. From the 40 or so people in attendance, someone asks, “if Europe doesn’t need such big trucks on its old, narrow streets, why do we?”
While this is a casual setting and much of the debate features good-natured ribbing, the stakes are high for public safety and the risk incurred by everyone each time a street gets constructed or rebuilt in San Marcos.
What is the conflict?
In front of your home, you probably want people to drive slowly down the street so kids can play in the roadway and you can walk to your neighbor’s house or to the store. You also probably want and expect a fast response from the fire department the moment there is an emergency. These reasonable desires play out as a conflict between traffic safety advocates and fire departments when communities decide on the width of streets and traffic lanes. Both sides argue that small changes in width can have a huge impact: we might be talking 6 inches over a single lane, or a couple feet for a full road.
Traffic safety advocates focus on design speeds, the speed that drivers feel most comfortable traveling. They argue that lower design speeds reduce the likelihood of collisions occurring and reduce the severity when they do happen. Two factors that impact design speed are the width of the roadway and the width of the lane.
On the other hand, firefighters prefer wide open roadways so they can quickly arrive on scene and, when necessary, deploy their vehicles with stabilizers to hold the vehicle in place when they need a ladder in the air. For fire apparatus designs common in North America, that leads to neighborhood streets that are unblocked by curbs or parked vehicles for at least 20 feet from curb to curb.
Design speed and safety
On neighborhood streets in American communities, thousands of people are killed each year in traffic collisions. Many more are severely or permanently injured. When people drive faster, they are more likely to end up involved in a crash that leads to severe injury or death. Any way to encourage lower driving speeds can make a given street segment a bit safer to travel on or across.
Elements that influence design speeds include distractions that may exist alongside or in the roadway, as well as temporary environmental conditions like lighting and weather. Design speed is not much affected by legal speed limits, although posted speed limits are often determined by design speed. Design factors that encourage slower, and safer, driving behavior include narrow roadway widths, meaning the total drivable space from curb to curb, and narrower lane widths (between about 9’-2” and 10’-8”) which determine how much space a vehicle has apart from its neighbors.
In one study looking at suburban roadways, after accounting for multiple other factors, lane width explained 25% of variability in driver speeds. The researchers estimated that for every additional foot in lane width above about 10’, drivers drove 3 miles per hour faster – a speed change that begins to greatly affect the likelihood of survival for someone hit by a vehicle.
Road design and emergency vehicle response
For firefighters, the goal is to respond to emergencies as quickly as possible. Fire engines are beasts over eight feet wide, so firefighters who drive these vehicles want roads designed for quick speeds, with few obstacles. This preference translates into roads with large turn radii at intersections, wide travel lanes, and limited on-street parking. Once these first responders arrive on the site of an emergency, they prefer to have a wide, flat roadway to park their truck and deploy the stabilizers. Ideally, firefighters want to be able to drive past another truck parked in the other lane, and a truck with stabilizers deployed can be up to 20 feet wide.
Why use such big trucks? They allow for tall ladders to get firefighters up in elevation onto multi-story buildings, and to get water hoses above the fire in the case of shorter structures. In addition, the trucks store some water and include pumps to maintain high water pressure from distant hydrants.
Some of the attendees at the debate in San Marcos argued that such large vehicles aren’t necessary, that older cities in places like Europe have far narrower streets and smaller fire response vehicles. Chief Stephens pointed out several differences between those cities and what he’s seen in Texas: people in the U.S. typically have a higher expectation of fire department response, and materials in buildings in the United States have changed in recent decades leading to hotter fires requiring more intense equipment.
In addition, fire departments in the US receive an ISO (Insurance Services Office) rating based on various factors, including the quantity and size of fire engines. Because a community’s ISO rating greatly affects insurance rates for property owners, fire chiefs are heavily encouraged to follow ISO standards.
Total lives saved should be the bottom line
When considering public safety impact of street widths, it makes sense to consider the total number of lives that can be saved, or the total number of severe and permanent injuries that can be avoided, regardless of the source of injury. And there may be other, indirect safety and health effects that are influenced by road width.
Consider flooding. Road width has a major impact on how much land in a community is impervious to rainwater, which increases the likelihood and severity of downstream flooding during large rain events. According to Andrea Bates, an Environmental Program Coordinator for Watershed Protection at the City of Austin, about 30% of all impervious cover in the city is roadways. Since roads channel water away from an area and reduce upstream flooding, they do affect floodwaters. However, she says, “if we’re talking about designing new roads, wider wouldn’t necessarily be safer and would contribute more to potentially downstream flooding” by increasing the amount of land impervious to rainwater.
As well, she points out that roadways have limited space, so every extra foot of road width creates an opportunity cost in terms of the loss of other potential amenities: rain gardens and street trees, for example, which are alternatives for reducing water runoff and improving water quality. Wider roads can take up space otherwise used for housing, which can raise the cost of living in a community. Other missed opportunities include potential space for wide sidewalks, bike infrastructure, and benches, which all point to another health impact of street widths.
Road width can influence physical activity levels, by discouraging walking and bicycling if streets are uncomfortably wide to cross or the design speed makes traffic too fast for casual bike use. If reduced road widths lessen the distance it takes for people to walk across a road and reduce the speed at which cars travel past, these changes could encourage a bit more physical activity by all people in a neighborhood.
Comparing risks, apples to apples
To understand which risk factors might be most strongly influenced by road and lane width decisions, it’s important to understand the scale of each problem – and it turns out that each of the safety and health issues exist at different orders of magnitude. Flooding kills roughly 100 people in the US each year, so shaving a few feet off the width of a specific roadway will probably not affect the likelihood of drowning in a flood for anyone downstream – but since flooding leads to a significant amount of property damage, it is still good to consider flood mitigation in such a calculation.
Fires are a more serious threat, with 3,459 civilians and firefighters killed in structural and vehicular fires in this country in 2016. Similar to floods, fires also have a major impact on property damage which raises insurance costs and meaningfully impacts quality of life for many.
Traffic crashes kill about ten times the number of people killed in fires in the US. This does not mean that street or lane width has ten times the impact on crashes as do fires, since they occur in different areas and each has many other contributing factors. Still, it suggests that the risk of fires is less than that of crashes, so we should consider modifying our priorities accordingly.
The big wild card turns out to be physical activity levels, and how much street width influences those. In 2015, 1,359,371 people between the ages of 40 and 79 years died in the United States. According to physical activity researchers from the Lancet Physical Activity Series Working Group, about 10.8% of deaths in this age range could have been averted had physical inactivity not been an issue – almost 150,000 people per year. Even a small increase in overall physical activity levels could nudge the overall mortality rate down and save thousands of lives per year – perhaps preventing as many deaths as are caused by fires.
Deaths due to chronic health conditions like heart disease and cancer are less violent than fatalities from car crashes and fires, and they are perhaps less clearly connected to a specific road design choice. However, they are so common that even reducing a small percentage of such deaths can result in a meaningful improvement in health outcomes.
“It’s also important to recognize that there are other design issues that have a more significant impact on emergency vehicle movement and responses” than road or lane width, according to Simon Evans, an Austin paramedic. Some of his suggestions are to build a more resilient gridded street network and to give emergency vehicles preemption rights at traffic signals.
A solution he says could reduce EMS response time by several minutes per call in some situations would be to implement standardized address and building numbering systems for large housing complexes. In such residential areas, older developments built prior to accessibility reforms in the early 1990’s also lack elevators and ramps, which makes transporting patients much more challenging.
Similarly, Austin Firefighter Whitney Ford sees major issues in accessing fires on private property with extremely narrow and often clogged lanes, specifically in storage facilities and low-rise industrial and retail areas.
The San Francisco Fire Department has purchased specialized, smaller fire engines to respond to fires in denser parts of that city, and such context-specific solutions can help achieve safer traffic and better emergency response. In Milwaukee, trucks were bought specifically to handle sharp corners in older neighborhoods. Fire departments in many communities have found ways to make sure their engines work given the constraints they face.
A point of agreement for the debaters in San Marcos is the value of painted bike lanes, since they can encourage physical activity while giving firefighters extra pavement they can use in emergencies. Urban designer Heyden Black Walker, who attended the debate, further argues in favor of expanding bike lanes protected from vehicular traffic, which are safer than the painted variety because they better separate road users. As well, protected bike lanes could be designed in such a way so as to give firefighters the space they need to get the job done.
If you’re interested in digging into this issue further, the Los Angeles County Public Health Department contracted a guide of best practices for “Emergency Access in Healthy Streets” in 2013.
So who wins?
When each issue is addressed alone, the solutions can unintentionally lead to greater problems elsewhere. That’s why determining ‘how wide a street should be for emergency response’ or ‘how wide a street should be for pedestrian safety’ should really be combined to identify how wide a street should be to reduce the risk of injury, illness, or death, from all causes.
Both Matt Lewis and Chief Les Stephens were right that road width influences public safety. So who won the debate? I would argue that they both won in demonstrating the value of collaboration to solve tricky issues like road widths. If passionate and intelligent leaders in other communities can respect each other and work together like they do in San Marcos, then community safety wins everywhere.
Nic is a biostatistics student completing the Master of Public Health program at the University of Texas Health Science Center at Houston. He is passionate about shaping the built environment to improve health outcomes. Reach him on Twitter: @NicWillMoe.