America’s roads just keep getting wider. According to a Washington Post report, over a third of U.S. states spent more than $19 billion on expanding existing highways and road infrastructure in 2019. [1]

It’s a common way to attempt to curb the traffic congestion plaguing U.S. cities, but many transportation buffs say it’s the wrong approach. In fact, America’s road safety troubles may be directly related to its bloated urban corridors. The data appears to indicate that, in many cases, our roads don’t need to be fed more pavement — they need a diet.

The Federal Highway Administration (FHWA) points out that undivided four-lane roads — so ubiquitous in American cities — play host to a wide range of dangerous collisions, from lane-changing side swipes to bike and pedestrian crashes. These crashes are directly related to the volume and speed of traffic, but they’re also tied to the width and layout of the road. And, while it may seem counterintuitive, the path to increased safety without worsening congestion often lies in reducing lanes, rather than adding them, through a method called road diets. [2]

In this article, we’ll explore how road diets work to increase safety not only for vehicles, but also for pedestrians and cyclists. We’ll tackle the following:

• What is a road diet?
• Key safety considerations
• How effective is a road diet?
• Considering the alternatives
• Finding the best approach with big data

So, What Is a Road Diet?

A road diet, or lane reduction, is a type of traffic calming measure designed to reduce speed and traffic congestion on an existing undivided roadway. Instead of expanding the existing road width with additional lanes, planners reduce the number of standard traffic lanes to make room for other types of lanes or road features.

Road diets are most common on four-lane highways. Typically, planners exchange the existing four driving lanes for a center left-turn lane flanked by two standard driving lanes and bike or pedestrian lanes. Other road diet examples include replacing two lanes with a tree-lined median or adding parking on the sides and narrowing existing lanes.

Whatever the specific approach, the overarching goal of a road diet is simple: to lower traffic speed and thus reduce the number and severity of crashes. In the process, this measure can also enhance the overall quality of life and appeal of an urban area by making more room for cyclists and pedestrians, expanding common areas, and even adding more green space to popular thoroughfares.

Key Safety Considerations

Understanding the value of road diets first requires an appreciation of just how threatening many of our busy four-lane, undivided roadways are. These popular road layouts are riddled with safety concerns for drivers, passengers, pedestrians, and cyclists alike. Before making any change to an established roadway, it’s essential to understand the dangers of the existing layout.

For Vehicles

In urban and suburban areas, four-lane, undivided highways are hot zones for vehicle-to-vehicle crashes. There are simply too many potential collision points for drivers to track. Such corridors are commonly home to all sorts of collisions:

• Rear-end collisions from sudden stops or vehicles waiting to turn
• Sideswipe crashes during lane changes
• T-bone or angle collisions from cars turning left across oncoming traffic
• Multi-car crashes at intersections

These collisions occur due to a range of factors, many of which can be addressed through road diets. High speed differential between lanes or intersecting streets can lead to sudden stops or miscalculations that result in collisions. Left turns across multiple lanes are also inherently dangerous. [2]

The specific traffic patterns and risks vary by location. When assessing the potential benefits of lane reductions, planners need data that allows them to analyze metrics like average speed, speed differentials, average traffic volumes, and typical turn counts at intersections.

For Pedestrians

As problematic as four-lane roads are for vehicle-to-vehicle crashes, they’re even more hazardous for pedestrians. Drivers hit and killed more pedestrians in 2022 than in any year since 1981, and these types of roads are at the center of many such collisions. [3] As one recent study revealed, 97% of the hot spots for pedestrian deaths in the U.S. are multi-lane roads. [4]

Crashes on such roads occur for many reasons, from a lack of sidewalks to pedestrians misjudging oncoming vehicles when crossing multiple lanes. However, the central problem on wide urban streets is vehicle speed. Studies show that pedestrians are five times more likely to die from crashes when cars are traveling at 40 miles an hour than at 20 miles an hour.

Here again, data is crucial for determining the right solution. Understanding vehicle speeds, the volume of pedestrian traffic, and the frequency of pedestrian collisions can help planners assess whether a road diet — and which type — would provide an effective solution.

For Cyclists

According to the National Safety Council, more than 850 cyclists died in collisions with vehicles in 2021. [5] Many of these incidents were linked to unsafe road conditions. [6] The FHWA reports that the simple addition of a bike lane could reduce bike crashes by 49% on four-lane roads. [7]

Beyond being an argument for bike lane additions, this is a strong point in favor of considering road diets on cyclist-heavy city roadways. Road diets are designed to reduce traffic speed, and they can make room for more extensive road modifications such as protected bike lanes, which are physically separated from vehicle traffic.

How Effective Is a Road Diet?

Overall, the data shows that road diets are often highly effective at increasing safety. Based on broad studies, the FHWA states that road diets can reduce crashes by between 19% and 47%. [2] In Seattle, a 2008 road diet reduced pedestrian collisions by 80%. The same project saw a 35% increase in cyclist traffic without any increase in bicycle-involved crashes.

To project the impact in a specific area, planners must account for various factors, particularly existing traffic volume. Lane reductions tend to be most effective on roads with between 8,000 and 20,000 average daily vehicles. [8]

Despite these benefits, many people are skeptical of road diets. In Los Angeles, the firefighters union recently launched a campaign against proposed road diets, claiming they would hinder emergency vehicles by increasing congestion. [9] Others argue they would slow down public transportation or simply divert heavy traffic elsewhere. [8]

Broadly speaking, the evidence to support these claims is slim. Although lane-reduction projects occasionally get pulled back, research shows that these road diet failures often occur due to a disconnection between public perception and reality. In other words — the project accomplishes its goal, even if the public thinks it’s not working.

That’s not to say these tactics are the right solution for every safety or traffic congestion problem. However, the evidence does indicate that when planners closely evaluate the many variables of a situation and decide to implement a road diet, the resulting safety enhancements are usually significant. [10]

Finding the Best Approach With Big Data

As noted, road diet success is much more likely with a deep analysis of traffic patterns. Understanding metrics like turning movement counts, average daily traffic volume and speed, speed differentials, and stopping frequency is essential for an accurate assessment of any potential project.

Big data platforms like StreetLight InSight® can expedite data collection when evaluating a potential road diet, providing detailed visualizations of traffic patterns and trends to help planners conduct a thorough road safety audit before making any decisions. This approach also makes the data collection itself safer because agency staff need not put themselves at risk to take manual counts along dangerous roadways. Furthermore, big data can provide a more complete view of roadway conditions than manual counts, which are usually limited to a small snapshot of traffic during peak driving hours on a particular day or a few days.

Many agencies are already using big data to evaluate potential road diets, as well as the success of past road diets. As the video below explains, Maine’s Department of Transportation used Streetlight tools to conduct a detailed analysis of its Bangor Street road diet proposal, filling in critical data gaps to understand turning movement counts, side-road traffic, and complex roundabout traffic flows.

Similarly, a StreetLight analysis of roadway capacity, vehicle speeds, routing patterns, and pedestrian activity suggested that a road diet on Oakland’s Grand Avenue could help address safety concerns without causing major congestion.

After implementing a road diet, big data transportation analytics also allow planners to easily measure any changes in traffic volumes, routing, safety, and critical metrics like Vehicle Hours of Delay (VHD). These insights simplify the process of assessing project potential and outcomes so planners can do their work more effectively.

For more information on how big data can help you find the best safety solutions for your streets, check out our Safety Data Handbook.

1. The Washington Post. “Infrastructure plan calls for fixing the nation’s existing roads. Some states are still focused on expansion.” https://www.washingtonpost.com/transportation/2021/05/23/highway-funding-infrastructure/
2. U.S. Federal Highway Administration. “Road Diet Informational Guide.” https://safety.fhwa.dot.gov/road_diets/guidance/info_guide/ch1.cfm
3. Governors Highway Safety Administration. “Pedestrian Traffic Fatalities by State: 2022 Preliminary Data.” https://www.ghsa.org/resources/Pedestrians23
4. Journal of Transport and Land Use. “United States fatal pedestrian crash hot spot locations and characteristics.” https://jtlu.org/index.php/jtlu/article/view/1825
5. National Safety Council. “Bicycle Deaths.” https://injuryfacts.nsc.org/home-and-community/safety-topics/bicycle-deaths/#:~:text=In%202021%2C%20most%20deaths%20occurred,for%20Health%20Statistics%20mortality%20data
6. NPR. “More cyclists are being killed by cars. Advocates say U.S. streets are the problem.” https://www.npr.org/2022/05/25/1099566472/more-cyclists-are-being-killed-by-cars-advocates-say-u-s-streets-are-the-problem
7. U.S. Federal Highway Administration. “Bicycle Lanes.” https://highways.dot.gov/safety/proven-safety-countermeasures/bicycle-lanes
8. AARP. “Road Diets: A Livability Fact Sheet.” https://www.aarp.org/content/dam/aarp/livable-communities/livable-documents/documents-2014/Livability%20Fact%20Sheets/Road-Diets-Fact-Sheet.pdf
9. Los Angeles Times. “Firefighters launch campaign against Measure HLA, saying ‘road diets’ threaten safety.” https://www.latimes.com/california/story/2024-02-14/firefighters-launch-campaign-against-measure-hla
10. Scientific Research. “A Comprehensive Study of a Road Diet Implementation in the US and Abroad.” https://www.scirp.org/journal/paperinformation?paperid=127799#:~:text=The%20road%20diets%20were%20implemented,were%20implemented%20across%2066%20projects

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In our increasingly suburbanized North American landscape, stroads are a cornerstone of the car-centric transportation paradigm. These bare-bones high-speed roadways are often devoid of any pedestrian- or bike-friendly infrastructure, subjecting drivers and non-motorists alike to dangerous conditions when commuting, shopping, or accessing essential services.

The drawbacks of the stroad stem from its hybrid nature: it attempts to connect people with key destinations (goods, services, city amenities) while also getting people from point A to B as quickly as possible. Far from being the best of both worlds, stroads often fail to accomplish either of these goals particularly well.

So what exactly is a stroad, and how can we make them less dangerous? In this article, we’ll discuss:

• What is a stroad?
• The problem(s) with stroads
• How to fix stroads
• Data to improve safety on stroads

What is a stroad?

The term “stroad” was first coined in 2011 by Charles Marohn to describe a roadway that combines elements of a street and a road.¹ So what is the difference between a street and a road?

Streets are destinations — they provide access to goods, services, and recreation. They are often found in dense urban cores, especially downtowns, where shops, restaurants, parks, salons, doctors’ offices, and more dot every corner. These kinds of roadways typically have fewer lanes, slower traffic, and signalized crosswalks to accommodate plenty of foot traffic.

Roads, by contrast, connect destinations to one another, prioritizing efficient traffic flow to get people from point A to point B. Consider a highway between cities, or between a downtown core and a suburb or exurb. These types of roadways typically have more lanes, higher-speed traffic, and limited to no access for non-motorists like walkers and bikers.

Stroads combine elements of both, acting as both destination and thoroughfare, which results in wide, high-speed roadways with sparse walking and biking infrastructure that are nevertheless crucial access points for goods, services, and recreation. These kinds of roadways are common around malls, strip malls, and other suburban hubs, but also frequently cut through urban cores — many downtown Main Streets are also stroads. Wherever they crop up, they usually feature speed limits between 20 and 50 miles per hour.²

When stroads manifest in the suburbs, it’s often because roads that were once used to connect suburban residents to the downtown core become attractive places for new shopping centers, restaurants, movie theaters, and more, boasting plenty of cheap space for sprawling supercenters and parking lots. Thus, roads that become host to these kinds of destinations are often doomed to morph into the dangerous stroad hybrid.

Stroads are also common in urban cores, especially where priority is placed on accommodating the high vehicle throughput that is common in these areas.

The problem(s) with stroads

In addition to being dangerous, stroads also have other negative impacts on public health and the local economy.

Why are stroads dangerous?

As mentioned above, stroads lack many of the necessary features that make streets safe for walking and biking, such as signalized crosswalks, protected bike lanes, slow vehicle speeds, and short crossing distances.

But it’s not just Vulnerable Road Users who experience dangerous conditions on stroads. These roadways are also difficult for drivers to safely navigate due to high-speed traffic across multiple lanes with many entry and exit points from driveways and parking lots providing access to roadside destinations.

Stroads often subject drivers to unprotected left turns to cross multiple lanes of high-speed traffic, or right turns where they could easily collide with cyclists and pedestrians traveling in the same direction across unmarked driveway crossings.

How do stroads impact emissions?

Stroads incentivize vehicle travel over lower emission forms of transportation like walking and biking. This, compounded by the fact that high-speed travel produces more emissions than slower driving, makes stroads emissions hotspots.

This not only contributes to climate-harming greenhouse gases, but also worsens air quality for those who live near these hybrid roadways.

Are stroads bad for the economy?

Although stroads connect consumers with shopping centers and other businesses, many are also unattractive and costly, compromising their ability to support the local economy.

Vast, undifferentiated expanses of asphalt and concrete are common to stroads, multi-lane roadways and parking lots dominate the landscape. Coupled with poor safety, this creates an uninviting environment, disincentivizing frequent trips and extended visits.

These factors also make stroads costly. While these high-volume, high-speed roadways must undergo expensive maintenance due to considerable wear and tear, they also often generate less economic activity and property tax revenue than true streets do.³

How to fix stroads

Fixing a stroad isn’t always simple, because they represent a confluence of competing land use and transportation goals: promote efficient vehicle travel while also facilitating economic opportunity and access to goods, services, and recreation.

A stroad usually evolves because land use practices have already allowed for business developments along an existing roadway, at which point it is too late to prevent the evolution of a stroad, but not too late to fix it.

Can stroads be prevented?

But it is possible to prevent the creation of a stroad in the first place through intentional land use practices. This would involve restricting new development along existing roads and allowing for more dense development along more people-friendly streets. Restricting the expansion of existing roadways (through lane widening or added lanes) can also help prevent street-to-stroad evolutions.

Similarly, reducing or eliminating parking minimums can allow for denser, less car-dependent hubs of development while also incentivizing non-vehicle modes of travel.

Preventing stroads could also involve converting roads into streets when new developments are proposed along existing roads. Below, we’ll explore some strategies for turning roads or stroads into streets.

Turning stroads into roads

Because stroads already have businesses, services, and/or city amenities in residence, fixing a stroad usually means turning it into a proper street. Turning a stroad into a road is not always possible, because it might require removing existing destinations and potentially relocating them elsewhere — a costly, unpopular, and time-consuming prospect for businesses and residents alike.

In cases where stroads are converted into roads, this means prioritizing vehicle throughput, minimizing entrance and exit points along the road (e.g. reducing the number of driveways leading to shopping centers and other roadside destinations) and eliminating pedestrian and bike access to the road (potentially creating separated bikeways and pedestrians paths).

Turning stroads into streets

To make stroads safer, more sustainable, and better for the economy, cities can explore redesigning roadways to implement more street-like elements.

One powerful tool for turning stroads into streets is the road diet. Road diets remove or repurpose existing lanes of traffic in order to create safer, lower speed corridors. While this tactic is sometimes controversial due to concerns that removing lanes will increase congestion, careful traffic analysis often reveals that road diets do not create significant delays in travel time, especially if they make roadways safer for non-vehicle modes of travel or reroute a portion of traffic to other high-capacity roads.

Similarly, adding multimodal infrastructure, especially infrastructure focused on bike and pedestrian safety such as protected bike lanes, signalized crossings, and pedestrian islands can help eliminate the common dangers of stroads. A Complete Streets policy can establish helpful guidelines for turning stroads into streets that accommodate all road users.

In addition to road diets, other traffic calming tactics such as reducing speed limits, narrowing lanes, or adding street art and landscaping can protect vulnerable road users from one of the top factors contributing to high traffic fatality rates: dangerous vehicle speeds. While street art and landscaping have been shown to reduce average driving speeds, they also help beautify stroads, making them more inviting and better for business. Adding lighting and benches can also further these goals.

Reducing parking, especially in locations with vast parking lots such as shopping centers, also helps disincentivize vehicle use and encourage other modes of travel like public transit, walking, and biking. Furthermore, eliminating parking can also free up space for housing, parks, dining courts, or other developments that give people reasons to visit more frequently and for longer periods of time, boosting economic activity.

In any case, converting a stroad into a street often takes time and may involve multiple strategies, so cities should focus on incremental improvements.³

Data to improve safety on stroads

To find and fix stroads effectively, analyzing current traffic conditions is crucial. The following metrics can help planners and engineers understand where stroads are putting people at risk and determine the best strategies to address them:

• Vehicle speeds – to pinpoint which roadways may qualify as stroads and monitor risk for Vulnerable Road Users like pedestrians and cyclists
• Biking and Walking activity – to understand where Vulnerable Road Users contend with dangerous conditions and where to prioritize infrastructure to improve their safety and connectivity
• Vehicle volumes – to understand roadway capacity and help assess whether a stroad should be converted into a road or a street
• Routing and Origin-Destination patterns – to evaluate the potential for stroad-to-street conversions and where traffic could be rerouted or shifted to other modes like public transport
• Turning Movement Counts – to determine where traffic lights, signalized crosswalks, or signal retiming can keep traffic flowing while improving safety

For a comprehensive guide to transportation safety analytics, download our Practitioner’s Guide to Transportation Safety.

1. Ben Abramson. Strong Towns. “5 Telltale Signs You’re on the Stroad From Hell.” January 19, 2023. https://www.strongtowns.org/journal/2023/1/19/5-telltale-signs-youre-on-the-stroad-from-hell
2. Strong Towns. “What’s a STROAD and Why Does It Matter?” March 2, 2018. https://www.strongtowns.org/journal/2018/3/1/whats-a-stroad-and-why-does-it-matter
3. Reliance Foundry. “Bad Urban Design: How do you fix a stroad?” https://www.reliance-foundry.com/blog/how-to-fix-a-stroad

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