Scene cones, protective vehicles and incident barriers: how crews protect a roadway scene
How crews layer warnings, blocking vehicles and barriers, and how drivers can help
Safety Behind the Wheel Foundation built this guide from Federal Highway Administration (FHWA) traffic incident management guidance, National Institute for Occupational Safety and Health (NIOSH) data, Occupational Safety and Health Administration (OSHA) guidance and published research on responder safety. Every source is listed at the end.
Why the roadside is a workplace
A collision scene on a busy road has two hazards. One is the wreck. The other is the stream of traffic still coming toward it. Responders must work in the thin space between the two.
Federal highway officials call the whole effort traffic incident management, or TIM. It is a planned process, shared by many agencies, to detect incidents, respond to them and clear them so traffic can move again as safely and quickly as possible [1]. Done well, it also cuts the number of secondary crashes [1]. A secondary crash is a new collision set off by the first one.
The risk to crews is real. From 2014 through 2023, 154 officers died in line of duty events where a vehicle struck them. That was 9% of all officer line of duty deaths in those years [11]. Add collisions in patrol cars, and motor vehicle events caused 496 officer deaths, or 29% of the total [11].
Tow operators face high risk too. A 2019 safety study notes that national fatality rates for tow operators exceed those of other first responders who do traffic incident work [13]. In the OSHA case files the researchers reviewed, about nine in ten cases fit one of two patterns. Either the worker was struck, mostly by traffic or rolling vehicles, or the worker was caught in or between vehicles and equipment [13].
A 2023 study of 5,113 news reports about responder incidents points the same way. Tow truck drivers were more likely than other responders to appear in a report of a line of duty death [12]. Drunk or drugged driving was a major cause, and the deaths were more likely in the early morning [12]. News reports are not a full count, so treat these as patterns, not totals. OSHA also lists struck by events among the common hazards for highway workers [10].
Every unprotected scene also raises the chance of another collision that could hurt survivors waiting for help. Our guides to work zone and move over safety and post crash care cover what drivers and survivors should do. This guide covers the gear and methods crews use.
Three layers: warn, block, separate
No single device keeps people safe. Crews stack layers so that when one fails, another still helps. Each layer has its own job.
Comparison compiled by Safety Behind the Wheel Foundation
Three layers of protection at a roadway scene
| Layer | What it does | Typical tools | Main limit |
|---|---|---|---|
| Warn | Tells drivers early that something is ahead and guides them around it | Cones and advance warning signs [6] | Does not stop a vehicle |
| Block | Puts a heavy vehicle between traffic and the people working | Fire, police, tow or patrol vehicles, some with arrow boards [5] | Works only if placed well and left in place |
| Separate | Absorbs or redirects a vehicle that gets through | Truck mounted crash cushions and temporary barriers [9] | Needs space, crash testing and correct setup |
The national manual for traffic control devices says crews should manage traffic incidents by following the principles in its own chapter on the topic [9]. That manual is the Manual on Uniform Traffic Control Devices, or MUTCD. Warning lights and scene lighting are covered separately.
Scene cones and advance warning
Cones are the most familiar tool. They are also the most misunderstood. A cone does not protect anyone. It tells drivers what to do and where to go.
Crews use cones and signs to build a taper. A taper is a slanted line of devices that guides traffic out of a closed lane. The national TIM course teaches responders how to set one up and how to choose devices for advance warning [4]. A dedicated response vehicle can make sure enough cones and advance warning signs are on hand when a crew arrives [6].
Three habits matter most:
- Give drivers distance. Warning has to start well before the wreck so drivers can slow and merge.
- Keep devices clean and bright. A faded or dirty cone is easy to miss.
- Pick everything up. Cones left behind after the scene clears confuse the next driver.
Follow your agency’s traffic control plan for the size, spacing and number of devices.
Cones also have a hard limit. They are light. A car at highway speed will scatter them and keep going. A row of cones is a message, not a wall. That is why people on foot should work behind a protected position, never behind cones alone.
Protective vehicles: using mass as a shield
FHWA notes that strategically positioned vehicles protect responders by acting as a barrier between them and approaching traffic [5]. Crews call these protective or blocking vehicles. Fire apparatus, police units, tow trucks and highway service patrol trucks all do this job.
The MUTCD describes a similar idea for moving road work. It calls it a shadow vehicle. This is a vehicle with lights and warning signs that can protect workers from errant vehicles, and it may carry a rear mounted impact attenuator [9]. An attenuator is a crash cushion built to absorb the energy of a hit.
One Texas fire department turned two surplus fire apparatuses into blocking vehicles for freeway incidents. It fitted them with truck mounted attenuators and arrow boards [5]. The example shows how an agency can set aside a vehicle just for this job.
The national TIM course also covers “Lane +1” blocking, which is a way of positioning the blocking vehicle, and the difference between “Move It” and “Work It” incidents [4]. Ask your local TIM trainer how crews in your area apply both.
A first arriving crew’s routine
Here is a typical order. Your agency’s training and procedures always come first.
- Size up the scene on approach. Note traffic speed, blocked lanes, injuries and hazards [3].
- Park the protective vehicle upstream of the wreck and the crew, so it shields the work area.
- Put on high visibility apparel before stepping out.
- Set warning devices from the protected side, following the traffic control plan.
- Decide whether vehicles can be cleared from the lanes quickly or the crew must work in the road for longer.
- Keep the protective vehicle in place until the crew and gear are out of the road. Then reopen the lanes.
Barriers and crash cushions: separation for longer jobs
A truck mounted attenuator is a crash cushion fixed to the back of a heavy truck. Researchers describe the truck as a vehicle placed to absorb the impact of errant vehicles [15]. The cushion is meant to soften a hit, which protects both the crew and the driver who strikes it.
Temporary barriers are the other tool. These are sturdy walls placed along a work space. The MUTCD says planners should weigh several factors when placing them [9]. These include how close workers are to traffic, how fast traffic moves, how long the work will last, the time of day and the traffic volume [9]. The same manual says normal curbing is not a substitute for a temporary barrier when one is needed [9].
Setting a barrier takes time and equipment. It fits a long closure better than a quick fender bender. Crews should still ask early whether a scene will run long, because a major crash investigation can turn a short call into hours.
What “crash tested” means
FHWA says hardware such as barriers, sign supports and work zone devices is commonly used to reduce the severity of roadside collisions [8]. FHWA also keeps a public list of eligibility letters for this hardware. The list has a column for test criteria, and recent entries name MASH [8]. MASH is short for Manual for Assessing Safety Hardware. Ask for proof of testing before you buy or approve any attenuator or barrier.
Limits of barriers and cushions
- They work only when set up as the maker and the agency specify.
- They need room. A cushion with no space to slow a vehicle cannot do its job.
- They guard against drivers who drift into the work area. They do not protect a crew member who steps out from behind them.
- After any hit, the maker’s instructions control inspection and reuse.
Training, apparel and staffing
The gear is only half the answer. FHWA describes its national course for the people who use it as free [2]. The four hour National TIM Responder Training covers scene size up, safe vehicle positioning, scene safety, command, traffic management, special cases and clearing the scene [3].
It is meant for every kind of responder, including fire and rescue, EMS, law enforcement, public works, towing and recovery, highway service patrols, traffic management centers and dispatchers [3]. As of October 2025, more than 800,000 people had finished it, and the national goal is 1.3 million [3]. FHWA lists state contacts for local training [3].
Does training pay off? A review of emergency service vehicle incidents linked enhanced driver training to 19% to 50% fewer incidents and risk management programs to 19% to 58% fewer [14]. These incidents include collisions, rollovers and roadside struck by events. The review warned that few studies had solid outcome data, so treat the numbers as rough [14]. A tow safety study also urged initial and refresher training for tow companies [13]. Safety Behind the Wheel Foundation encourages every responder agency and tow company to make that training routine.
Be seen
The MUTCD sets a standard for workers in a temporary traffic control zone, including emergency responders. They must wear high visibility apparel that meets Performance Class 2 or 3 of the ANSI/ISEA 107 standard [9]. The national TIM course also covers apparel for responders [4].
Small and rural agencies
Manual traffic control takes more people, and some rural response teams rely on volunteers [7]. Local agencies can learn from a Florida city that set up a dedicated response vehicle. In its first six months, the vehicle handled 193 lane blocking events. It saved nearly 5,000 minutes of lane blockage on arterial roads [6].
Who chooses and buys the gear
Fire departments, EMS agencies, towing companies, road agencies and trained workplace responders such as plant emergency teams are the usual buyers. They buy from professional emergency equipment suppliers and authorized dealers. Common channels include fire apparatus dealers, traffic safety equipment distributors and truck equipment dealers that install lights and attenuators.
On a public road, the agency in charge chooses, designs and installs the devices. Employers choose gear for their own trained teams. Neither job belongs to a resident, a parent group or a school board. Do not put cones, barrels or barriers on a public road yourself. Ask the agency to review a trouble spot instead.
Care, inspection and common mistakes
Protection gear wears out in quiet ways. Inspect it on a schedule, not just after trouble.
- Cones and signs: Look for cracks, fading, lost reflective bands and dirt. Count them back onto the truck after every call.
- Blocking vehicles: Test arrow boards and lights at the start of each shift.
- Crash cushions: Check mounts and latches. After any hit, take the unit out of service until it is inspected under the maker’s instructions.
- Apparel: Wash it as directed and retire vests that are faded or torn.
Comparison compiled by Safety Behind the Wheel Foundation
Common scene protection mistakes and better habits
| Common mistake | Why it matters | Better habit |
|---|---|---|
| Setting cones before the protective vehicle is in place | A crew member stands unprotected in a live lane | Position the vehicle first |
| Treating cones as a barrier | A cone will not stop a car | Keep people behind the vehicle |
| Staying longer than needed | Each extra minute adds exposure and delay [1] | Clear lanes as soon as it is safe |
| Leaving devices behind | Drivers meet a warning with no hazard | Pick up everything and count it |
| Using worn out gear | Faded devices are easy to miss | Inspect and replace on a schedule |
What drivers and neighbors can do
When you see cones, an arrow board or a vehicle across a lane, slow down early. Merge when it is safe, and obey hand signals from officers and flaggers. Keep your phone down and do not stop to look. Move over laws differ by state, so see our guide to move over laws by state.
If you are the one in a car accident, crews may block lanes around your car. They may ask you to stay put or to move to a safe spot. Follow their directions. Their placement protects you as well as them.
Community members can help in calm, practical ways:
- Ask your fire chief, sheriff or state DOT TIM coordinator whether local responders have taken the national course [3].
- Ask whether the area has a protective vehicle, and who pays for training and gear.
- Report damaged or abandoned devices to the road agency. Do not move them into traffic yourself.
- Small employers with trained response teams should align their procedures with local agencies and the MUTCD [9].
Frequently asked questions
What is the difference between a protective vehicle and a barrier?
A protective vehicle is a truck or other vehicle parked to shield the crew. A barrier is a purpose built wall or cushion made to absorb or redirect a hit. Many crews use the first. Longer jobs may add the second. A protective vehicle fitted with a truck mounted attenuator does both jobs [5, 15].
Should I put out cones or triangles if I stop at a wreck?
Walking into the road is dangerous. For most drivers, the safest steps are to get clear of traffic, use hazard lights and call 911. Cones are tools for trained crews with a protective vehicle. Our roadside breakdown guide covers what to do if your own car is stopped.
Why do emergency vehicles block a lane when the collision is on the shoulder?
The blocking vehicle gives the crew a buffer. FHWA notes that well placed vehicles act as a barrier between responders and approaching traffic [5]. The crew may park across a lane even when the wreck is on the shoulder. Slow down, merge when you can and follow directions.
Who is allowed to place devices on a public road?
Authorized agencies and trained responders do this work under traffic control plans. Residents, school groups and businesses should not place cones, barrels or barriers on public roads. If you see a hazard, call the road agency, or 911 in an emergency.
What does “crash tested” mean for incident gear?
It means the device was put through crash tests against a set standard. FHWA’s public list of eligibility letters shows the test criteria for each listed device, and recent entries name MASH [8]. Ask the supplier for the letter or test report. Do not accept a general claim that a device is “tough.”
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation urges every response crew to use layered protection backed by training, and asks drivers to slow down and move over near any scene. Cones, protective vehicles and barriers do different work. Cones guide drivers. Vehicles shield people. Barriers and crash cushions absorb the force when a driver does not stop. Crews need all three, plus training and visible apparel, to stay safe in the road.
For drivers, the lesson is simple. When you see these devices, slow down, move over when it is safe and follow directions. The crew ahead is working close to moving traffic so that the people in the collision can get help.
Related articles
Sources and further reading
- 1Federal Highway Administration, Office of Operations. Welcome to Traffic Incident Management (TIM). Updated date not stated on page. ops.fhwa.dot.gov/tim
- 2Federal Highway Administration. Introduction to Traffic Incident Management: Saving Lives, Time, and Money (FHWA-HOP-22-14). Published 2022. ops.fhwa.dot.gov/…/IntroductiontoTIM_v2_508.pdf
- 3Federal Highway Administration, Office of Operations. National TIM Responder Training. Updated date not stated on page. Data year: training counts as of October 2025. ops.fhwa.dot.gov/tim/training/index.htm
- 4Federal Highway Administration (SHRP2). National Traffic Incident Management (TIM) Responder Training Program Train-the-Trainer Program Overview. Last updated September 16, 2013. fhwa.dot.gov/…/TIM_TtT_Course_Overview.pdf
- 5Federal Highway Administration. TIM Postcrash Care Factsheet (Next-Generation Traffic Incident Management: Technology for Saving Lives, FHWA-HOP-24-064). Published 2024. ops.fhwa.dot.gov/…/fhwahop24064.pdf
- 6Federal Highway Administration. Next-Generation Traffic Incident Management on Local Roads (FHWA-HOP-21-036). Published 2021. Data year: first six months of one Florida city’s program (year not stated). ops.fhwa.dot.gov/…/EDC-6_Factsheet_TIM_LocalRoads_v2_508.…
- 7Federal Highway Administration. Rural TIM Factsheet. Publication date not stated. ops.fhwa.dot.gov/…/Rural_TIM_Factsheet.pdf
- 8Federal Highway Administration. Hardware Eligibility Letters. Updated date not stated on page (lists 2026 letters). highways.dot.gov/…/hardware-eligibility-letters
- 9Federal Highway Administration. Manual on Uniform Traffic Control Devices, 11th Edition, Part 6: Temporary Traffic Control. The current edition is the 11th Edition with Revision 1, dated December 2025. mutcd.fhwa.dot.gov/pdfs/11th_Edition/part6.pdf
- 10Occupational Safety and Health Administration. Highway Work Zones and Signs, Signals, and Barricades – Overview. Updated date not stated on page. osha.gov/highway-workzones
- 11CDC, National Institute for Occupational Safety and Health. Law Enforcement Officer Motor Vehicle Safety. Updated July 25, 2024. Data year: 2014 to 2023. cdc.gov/…/index.html
- 12Yang C, Liu J, Li X, Barnett T. Analysis of first responder-involved traffic incidents by mining news reports. Accident Analysis and Prevention. Published August 2023. Data year: 5,113 news reports (years not stated in the abstract). pubmed.ncbi.nlm.nih.gov/37572424
- 13Chandler MD, Bunn TL. Motor vehicle towing: An analysis of injuries in a high-risk yet understudied industry. Journal of Safety Research. Published 2019. Data year: OSHA investigation files (years not stated in the abstract). pubmed.ncbi.nlm.nih.gov/31862030
- 14Bui DP, et al. Interventions and controls to prevent emergency service vehicle incidents: A mixed methods review. Accident Analysis and Prevention. Published 2018. Data year: studies published in the decade before 2018. pubmed.ncbi.nlm.nih.gov/29621721
- 15Pourfalatoun S, Miller EE. User perceptions of automated Truck-Mounted attenuators: Implications on work zone safety. Traffic Injury Prevention. Published 2021. pubmed.ncbi.nlm.nih.gov/34037505
This article reflects the safety priorities of responder protection and traffic incident management. It is general education, not legal, medical, insurance or financial advice, and it is not a training course. Rules change, so verify details with official sources. Responders and employers should follow their agency's training, their state's traffic control rules and the current MUTCD. For a local scene or road, contact your state DOT, local public works office or fire chief. Questions about coverage or injuries belong with your insurer or doctor. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Scene cones, protective vehicles and incident barriers: how crews protect a roadway scene.” drivewithcare.org, https://drivewithcare.org/scene-cones-protective-vehicles-incident-barriers/. Reviewed October 2026.
Special thanks to our contributors
We appreciate the professionals, experts, and community members who share their knowledge and perspectives to help make this resource better. Your insights are always welcome and appreciated.
Have professional expertise, firsthand experience, or a perspective that could make this resource better?
We welcome your input. Your knowledge and experience can help us make this resource more useful, accurate, and meaningful to the people who rely on it.
Thank you. Your contribution is on its way.
We’re grateful you took the time to share your knowledge with us. Our team reviews every contribution with care. If it helps improve this resource, we’ll update the page and recognize you the way you chose.
Keep learning
Safe Driving Resource Center
Guides, self-checks and articles for drivers, parents of new drivers, and families recovering after a crash.
