Safer road design: a field guide to the safety fixes on your street
How to spot common road safety fixes, which crashes they prevent and how to use them
Picture a street you drive every day, where one week crews shrink its 4 lanes to 2 plus a center turn lane. A curbed island appears in the crosswalk by the bus stop, with yellow lights that flash when someone pushes a button.
It can feel like a hassle. To a roadway design engineer, though, each change answers two questions. How do people get hurt here? How can that become survivable?
The Federal Highway Administration (FHWA) counts 12,036 deaths in intersection related crashes in 2022, about 28% of the total (our calculation) [1]. Roadway departures caused 51% of deaths from 2016 to 2018 [2]. In 2024, 73% of pedestrian deaths happened away from intersections and 76% in the dark [3]. Here is what each fix looks like, which crash it targets and what it asks of you.
How engineers match a fix to a crash
Our Safe System guide explains the big idea. People make mistakes. Bodies have limits. This guide is the street level version. It starts with the crash type.
- Angle: one vehicle hits the side of another, often during a left turn.
- Head on: a driver drifts or passes into oncoming traffic.
- Run off road: a vehicle leaves its lane and hits a tree, pole or ditch, or rolls over.
- Rear end: a driver hits a vehicle that is slowing to turn or stopped.
- Pedestrian and bicyclist: a driver strikes a person walking, rolling or riding.
FHWA’s Safe System guidance for intersections comes down to four moves [13]. Cut conflict points, lower speeds, improve visibility, and give people walking and biking protected space. Practitioners usually reach for them in that order, because removing a conflict beats warning drivers about it.
Spot it on your street: a quick reference table
Comparison compiled by Safety Behind the Wheel Foundation
| Treatment | What you’ll see | Crash type it targets | Your role |
|---|---|---|---|
| Roundabout | Circular center island, yield signs at every entry | Angle, left turn and head on | Slow down, yield to circulating traffic, pick your lane early |
| Mini roundabout | Small domed or painted center you can drive over | Angle and left turn on neighborhood streets | Drive around the center unless you are in a large vehicle |
| J turn (RCUT) | Side street traffic must turn right, then U-turn at a median opening | High speed angle crashes on divided highways | Turn right, move left, U-turn; never cut across the median |
| Turn lanes and raised medians | Separate turn lanes, curbed medians, fewer driveways | Rear end, left turn and driveway crashes | Slow in the turn lane; plan for a U-turn or the next intersection |
| Refuge island | Curbed island in the middle of a crosswalk | Pedestrian crashes on wide, busy roads | Expect people waiting in the middle of the street; walkers cross one direction at a time |
| Curb extension (bulb out) | Sidewalk corner pushed out into the parking lane | Pedestrian crashes from hidden walkers and long crossings | Watch the corner; never park in the cleared area |
| Raised crosswalk or speed table | Flat topped hump, often marked as a crosswalk | Pedestrian and speed related crashes | Slow before it and yield to people crossing |
| Speed hump or cushion | Rounded hump; cushions have gaps for wide vehicles | Speed related crashes on local streets | Cross slowly; don’t swerve to aim for the gaps |
| Crossing beacons (PHB, RRFB) | Overhead red signal, or yellow lights flashing under a crossing sign | Pedestrian crashes at midblock crossings | Stop on red; treat a flash as a person crossing |
| Protected bike lane | Bike lane set apart by posts, curbs, planters or parked cars | Bicyclist crashes with passing and turning vehicles | Never stop in it; look for riders at corners and driveways |
| Road diet | 4 lanes become 2 plus a center turn lane | Rear end, left turn, sideswipe and pedestrian crashes | Use the center lane only to turn |
| Rumble strips | Grooves along the centerline or shoulder | Head on and run off road crashes | Steer back gently; if drowsy, stop and rest |
| Median barrier | Cable, guardrail or concrete wall in the median | Cross median head on crashes | Stay centered; report damaged barrier |
| Forgiving roadside | Open roadside, breakaway posts, guardrail, sloped pavement edge | Run off road crashes and rollovers | If you drift off, ease off the gas and steer back gently |
| Lighting | Bright poles at crosswalks and intersections | Nighttime pedestrian and intersection crashes | Lit does not mean safe; keep your speed down |
Intersections: removing the most dangerous turns
Roundabouts force every driver to slow down, travel one way and yield on entry, which removes left turns across traffic and high speed right angle crashes. FHWA reports 82% fewer fatal and injury crashes when a roundabout replaces a two way stop, and 78% fewer when it replaces a signal [4]. Our roundabout guide shows how to drive one.
A mini roundabout fits inside an existing neighborhood intersection. Its center island is fully traversable, so large vehicles can roll over it [7]. FHWA’s traffic calming guide notes that speeds inside one run about 40% lower than 350 feet away [7].
J turns. On a rural four lane highway, crossing straight from a side road means judging gaps in fast traffic from both directions. A restricted crossing U-turn (RCUT), or J turn, removes that move: you turn right, merge left, then U-turn at a median opening. FHWA reports 54% fewer fatal and injury crashes when a two way stop becomes an RCUT (2013 source) [4]. A related design, the median U-turn, moves left turns from the main road to U-turn openings past the intersection [4].
Turn lanes give turning vehicles their own space, out of the through lane. FHWA reports that adding left turn lanes cut total crashes by 28% to 48% (2002 source), targeting rear end and left turn crashes [4].
Crossings: shorter, slower and easier to see
Because most pedestrian deaths happen away from intersections and after dark [3], engineers focus on midblock crossings, bus stops and lighting.
- Refuge island: a curbed island lets walkers cross one direction at a time. FHWA reports 56% fewer pedestrian crashes [6]. It suggests islands at least 4 feet wide on busy multilane roads, ideally 8 [6].
- Curb extension (bulb out): the corner juts into the parking lane, so walkers stand where drivers can see them and cross a shorter distance. A study in FHWA’s traffic calming guide found fewer cars passed a waiting walker before a driver yielded [7].
- Raised crosswalk: a flat topped table 3 to 6 inches high lifts walkers into view and slows drivers to about 20 to 30 mph [7].
- Advance yield lines: white triangles, called shark’s teeth, with a sign 20 to 50 feet before the crosswalk [6]. Stopping there keeps you from hiding the walker from the next lane. FHWA links them to up to 25% fewer pedestrian crashes [6].
- Crossing beacons: FHWA reports 55% fewer pedestrian crashes at pedestrian hybrid beacons (PHBs), which show red, and up to 47% fewer at rectangular rapid flashing beacons (RRFBs) [6]. Our pedestrian safety guide explains each signal phase.
Bike facilities: from paint to protection
A painted bike lane marks space but relies on drivers staying out. A buffered lane adds a striped gap. A separated or protected lane adds something physical: flexible posts, a curb, planters or a row of parked cars.
Separation targets the crashes riders fear most: being hit by a passing vehicle or an opening door. The weak spots are corners and driveways, where turning cars cross the lane. Engineers usually reserve full separation for faster or busier streets. Our bicycle and e-bike guide covers an FHWA study comparing lanes separated by posts with painted lanes.
Drivers: never stop or park in a bike lane. Check your mirror and shoulder before turning right. Riders: slow at driveways. Take speed humps gently, since FHWA warns that hitting a 3 inch hump at 20 mph may cost a rider control [7].
Corridor speed design: streets that ask for the right speed
FHWA links a 10% risk of death to about 20 mph for a person on foot and 30 mph for a side impact [15]. So on streets with crosswalks and driveways, engineers try to make the safe speed feel natural.
Road diets turn 4 undivided lanes into 2 travel lanes and a center turn lane [8]. Left turners wait out of the flow. Walkers cross fewer lanes. Leftover space often becomes bike lanes. FHWA reports crash reductions of 19% to 47% [8].
Street cues. FHWA’s traffic calming guide calls these tools self enforcing, because physical and visual cues do the slowing [7]. Narrower lanes, street trees and buildings near the curb make a street feel tighter. Parking on the street alone typically trims speeds by 1 to 5 mph [7].
Traffic calming on local streets, usually those posted at 30 mph or less [7]:
- Speed humps are about 3 inches high and 12 feet long, slowing drivers to about 15 to 20 mph as they cross [7]. Studies of 51 humps found 33% to 48% fewer crashes [7].
- Speed cushions leave gaps for fire trucks and buses, so they suit emergency routes where humps do not [7].
- Speed tables are longer and flat topped, with crossing speeds of 25 to 35 mph. Studies of 27 tables found 36% to 64% fewer crashes [7].
- Chicanes shift the lane side to side, cutting typical speeds by 3 to 9 mph [7].
Access management: fewer driveways, fewer surprises
Every driveway is a spot where someone may turn left across traffic, stop suddenly or pull out blind. Access management closes or combines driveways, limits some to right turns in and out, and adds raised medians and turn lanes [5]. It targets left turn, angle and driveway crashes, including those involving people walking and biking [5].
FHWA reports 25% to 31% fewer fatal and injury crashes on urban and suburban arterials (2004 source) and 5% to 23% fewer crashes on rural two lane roads [5]. A raised median may mean a U-turn or a loop around the block. So plan for it rather than turning illegally.
Forgiving roadsides and highways
On rural highways and freeways, engineers make leaving the lane survivable. Curves matter most, since FHWA says they account for 27% of fatal crashes [9]. Our roadway departure guide covers recovery if your wheels drop off the edge.
- Rumble strips: on rural two lane roads, FHWA reports 44% to 64% fewer head on fatal and injury crashes with centerline strips [9]. Shoulder strips bring 13% to 51% fewer run off road ones. FHWA recommends gaps for bicyclists [9].
- Median barriers: flexible cable, steel guardrail or rigid concrete [9]. On rural four lane freeways, FHWA reports 97% fewer cross median crashes [9].
- Clear zones: open, drivable land beside the road where a driver can stop or regain control [10]. Width depends on speed, traffic and slope [10]. FHWA cites research finding 22% fewer crashes when roadside objects sat about 17 feet from the road instead of about 3 feet [9].
- Breakaway posts: sign supports inside the clear zone must break away on impact or sit behind a barrier [10].
- SafetyEdge: the pavement edge is shaped at about 30 degrees, so a tire can climb back smoothly [9]. Rural crashes involving edge drop offs are 2 to 4 times as likely to include a death. FHWA reports 11% fewer fatal and injury crashes [9].
Lighting: designing for the dark
FHWA reports that the nighttime death rate is 3 times the daytime rate, since only 25% of driving happens at night [11]. Lighting can cut nighttime injury crashes involving pedestrians at intersections by up to 42% [11]. Good crosswalk lighting makes the walker stand out against a darker background instead of appearing as a dark silhouette [6]. A bright crosswalk helps you see, but your stopping distance still depends on your speed.
Layers on one corridor: a before and after example
Now picture a distracted driver who misses the flashing RRFB, so that layer fails. The single lane has already slowed her. The curb extension makes the walker easier to spot. The walker also has only 1 lane to clear, not 4.
Safety scientists compare this to slices of Swiss cheese: each layer has holes. But a serious crash needs the holes to line up. The 2026 National Roadway Safety Strategy calls for a system that expects mistakes and offers multiple layers of protection [14]. It also notes that over half of traffic deaths happen on arterial roads, about 10% of the network [14].
How to request a safety improvement
Engineers act faster on requests that name a crash pattern and a place. Our guides to local crash data and safety maps and using crash data to set priorities show how to find the numbers.
Frequently asked questions
What is a J turn intersection and how do I use it?
A J turn, or RCUT, blocks left turns and straight crossings from a side road. Turn right, move left, U-turn at the marked median opening, then continue.
Why did my city take away a lane on a busy street?
It is probably a road diet: 4 undivided lanes become 2 plus a center turn lane. Turning drivers wait out of the flow. Walkers cross fewer lanes. FHWA reports 19% to 47% fewer crashes [8].
What is the difference between a speed hump and a raised crosswalk?
A speed hump is a rounded bump that slows drivers to about 15 to 20 mph [7]. A raised crosswalk is a longer, flat topped crossing that slows drivers to about 20 to 30 mph and lifts walkers into view [7].
Are protected bike lanes safer than painted ones?
Separation keeps passing cars out of the rider’s space, which paint cannot do. Risk remains at corners and driveways, so look for riders before turning.
How do I get a crosswalk, speed hump or roundabout near me?
Contact the agency that owns the road with the location, the crash pattern and the fix you think fits. Ask whether a road safety audit or safety action plan covers the site [12].
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safer roads work best when you work with them. Read the design cues on your street and follow them even when they feel slower. Speak up with specifics where crashes keep happening.
Related articles
- Safe System approach: how road design protects you from human mistakes
- Right of way rules: four way stops, crosswalks and roundabouts explained
- Pedestrian safety for drivers: how to spot, yield to and protect walkers
- Bicycle, e-bike and scooter safety: how drivers and riders share the road
- Local crash data and safety maps: how to find and read your area’s data
Sources and further reading
- 1Federal Highway Administration (FHWA). About Intersection Safety. Updated July 28, 2026. highways.dot.gov/safety/intersection-safety/about
- 2Federal Highway Administration (FHWA). Roadway Departure Safety. Updated August 25, 2023. highways.dot.gov/safety/roadway-departure-safety
- 3National Highway Traffic Safety Administration (NHTSA). Pedestrians: 2024 Data. Traffic Safety Facts, DOT HS 813 818. June 2026. crashstats.nhtsa.dot.gov/…/813818
- 4Federal Highway Administration (FHWA). Proven Safety Countermeasures fact sheets: Roundabouts (FHWA-SA-21-042), Reduced Left-Turn Conflict Intersections (FHWA-SA-21-030) and Dedicated Left- and Right-Turn Lanes at Intersections (FHWA-SA-21-041). Accessed October 2026. highways.dot.gov/safety/proven-safety-countermeasures
- 5Federal Highway Administration (FHWA). Proven Safety Countermeasures: Corridor Access Management. FHWA-SA-21-040. Accessed October 2026. highways.dot.gov/…/corridor-access-management
- 6Federal Highway Administration (FHWA). Proven Safety Countermeasures fact sheets: Medians and Pedestrian Refuge Islands (FHWA-SA-21-044), Crosswalk Visibility Enhancements (FHWA-SA-21-049), Pedestrian Hybrid Beacons (FHWA-SA-21-045) and Rectangular Rapid Flashing Beacons (FHWA-SA-21-053). Accessed October 2026. highways.dot.gov/safety/proven-safety-countermeasures
- 7Federal Highway Administration (FHWA). Traffic Calming ePrimer, Modules 2, 3 and 6. Accessed October 2026. highways.dot.gov/safety/speed-management/traffic-calming-eprimer
- 8Federal Highway Administration (FHWA). Road Diets (Roadway Reconfiguration). Accessed October 2026. highways.dot.gov/safety/other/road-diets
- 9Federal Highway Administration (FHWA). Proven Safety Countermeasures fact sheets: Longitudinal Rumble Strips and Stripes on Two-Lane Roads (FHWA-SA-21-036), Median Barriers (FHWA-SA-21-037), Roadside Design Improvements at Curves (FHWA-SA-21-029) and SafetyEdge (FHWA-SA-21-038). Accessed October 2026. highways.dot.gov/safety/proven-safety-countermeasures
- 10Federal Highway Administration (FHWA). Clear Zones. Updated August 6, 2025. highways.dot.gov/…/clear-zones
- 11Federal Highway Administration (FHWA). Proven Safety Countermeasures: Lighting. FHWA-SA-21-050. Accessed October 2026. highways.dot.gov/…/lighting
- 12Federal Highway Administration (FHWA). Proven Safety Countermeasures fact sheets: Road Safety Audit (FHWA-SA-21-048) and Local Road Safety Plans (FHWA-SA-21-033). Accessed October 2026. highways.dot.gov/…/road-safety-audit
- 13Federal Highway Administration (FHWA). Safe System Intersections. Updated March 12, 2021. highways.dot.gov/safety/intersection-safety/safe-system-intersections
- 14U.S. Department of Transportation (USDOT). National Roadway Safety Strategy: Safer People. Safer Roads. Safer Vehicles. Posted August 2026. transportation.gov/…/USDOT-National-Roadway-Safety-Strategy-2026.pdf
- 15Federal Highway Administration (FHWA). Safe System Approach for Speed Management, Table 5. FHWA-SA-23-002. May 2023. highways.dot.gov/…/Safe_System_Approach_for_Speed_Management.pdf
This article reflects the safety priorities of transportation safety engineering, roadway design and the Safe System approach. It is general education, not engineering, legal or professional advice for any road or person. Crash reductions come from specific studies and settings, so local results vary. Laws, designs and data change, so verify details with official sources. Reviewed October 2026.
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