Work zone safety

Find important information about traveling in and around roadway work zones, including information on traffic control training and certifications.

Image of a work crew with a lane closed and replacing a concrete panel in the roadway.

A work zone is an area of roadway with construction, maintenance, or utility work activities. A work zone is typically marked by signs, channelizing devices, barriers, pavement markings, and/or work vehicles. It extends from the first warning sign or rotating/strobe lights on a vehicle to the END ROAD WORK SIGN or the last temporary traffic control device.

There are many devices and pieces of equipment that go into setting up a work zone, and sometimes it isn't easy to understand why these are set up in a particular way. We also need your help to ensure that both the traveling public and the workers in the work zone make it home safely every day.

Driving tips


Merging doesn't have to be aggravating - if we can all be courteous. Merging areas tend to be where backups start, whether or not it is part of a work zone lane closure. Safe and efficient movement of traffic through the merging area approaching a lane closure depends on the ability of drivers to plan ahead, adjust their speed, and merge smoothly into a safe gap between vehicles in the open lane. When drivers merge more like a zipper, where vehicles in both lanes come together smoothly - even if not at full posted speed - everyone can get through the merge much quicker.

From a legal standpoint, it is the merging driver's responsibility to merge in a safe manner. However, it is illegal for drivers in the open lane to actively block merging traffic, including blocking part of the merging lane to prevent perceived cutting in line.

To help make merging smoother, plan ahead - there is no need to change lanes abruptly. If traffic is light, you can move over early and there should not be any issues. When traffic is heavier, you can wait longer before merging, and this can sometimes help with a smoother merge, as well as reducing the length of backups. It is legal to wait to merge until the lane closure devices (cones or barrels) start, but we recommend merging sooner than that to give more time to find a gap, complete the merge, and avoid getting in a pinch when the devices make the closed lane too narrow. Merging sooner also avoids the risk of hitting a closure device or ending up inside the work zone.

Breakdowns and collisions in work zones

If you happen to break down in a work zone, the first thing to remember is not to panic. If you're in a traffic lane, stay in your vehicle, turn on your hazard lights, and dial 911 if you have a phone. If possible, drive your vehicle to the right shoulder of the roadway. If you can get to the shoulder and it is safe, you can get out of your vehicle, raise the hood, and call/wait for help. Help should arrive soon.

Collisions are traumatic, even when there aren't serious injuries, but you need to remain as calm as possible and stay in your vehicle. If possible, drive your vehicle to the road shoulder (preferably the right shoulder) or other safe area, turn on your hazard lights, and call 911. Help should arrive soon.

A disabled or damaged vehicle in a work zone is even riskier to exit before help arrives, particularly on freeways, as there are more hazards than just the typical ones such as high speed traffic on a normally operating roadway. Additional risks include:

  • Shoulder or other unexpected drop-offs. Digging may have occurred just inside the work zone, and concrete barrier may be protecting not only workers but a significant drop-off or other hazard on the other side.
  • Rough and uneven surfaces, temporary pavement repairs, etc.
  • Construction equipment such as dump trucks and other heavy machinery

Do not climb over a concrete barrier, bridge railing, or similar obstruction. In most cases, the other side is not safe and could be a significant fall.

Cones, barrels and barriers

Long closure areas

Sometimes it may seem like a much longer section of roadway is closed compared to the area that work is actually being done. There are many reasons why a given length of roadway is closed, but the main reason is that the closure is set up to maximize productivity in a particular area. Work zones are usually observed by a driver for a very short period of time, but the work in the zone is very dynamic and may involve activities that move or multiple operations at once in different areas, and all of these activities are scheduled and synchronized to result in a finished product at a desired time. This applies to both log and short duration work. It is both more efficient and safer for workers to set up one long work zone rather than have to keep moving or adjusting shorter ones.

Common work operations that are not always easy to see:

  • Surveying, including data collection and staking
  • Preparation and cleanup work
  • Preliminary repair work operations
  • Utility work and relocations
  • Smaller operations supporting or done in advance of another larger operation

Closing multiple lanes

In many cases, it is not safe or feasible to perform a work operation within the limits of a single lane. Live traffic directly adjacent to road work, separated only by a lane stripe and cones or barrels, is extremely hazardous for both workers and drivers. Workers are at greater risk of being struck by an errant vehicle, and drivers are at greater risk of colliding with a piece of machinery or other equipment within the work zone. Longer term projects may use temporary concrete barrier as additional protection to separate traffic from the work zone.

In other cases, we may need to do work in more than one lane at once, or in a middle lane where it is not safe to try and direct traffic around both sides of the work area.

Standard practice is to close the least number of lanes necessary to safely and effectively perform the work. Lane closures are also analyzed for traffic delay impacts, and every effort is made to reduce those impacts as much as possible. Generally, the length of a work zone (closed lane) has minimal effect on traffic delay - the majority of the delay is generated where traffic merges into the reduced number of lanes. This is where using the "zipper merge" technique can help.

Long closure tapers

Tapers in work zones are a series of traffic control devices that shift traffic out of or back into its normal path. Taper lengths are designed to accommodate safe and efficient merging, both under normal circumstances - such as when merging onto a freeway - and as part of lane closures. The major consideration in taper length is traffic speed - higher speeds require longer tapers. A typical freeway lane closure requires a minimum 720 foot taper for a 60 MPH posted speed limit.

Construction signs

Construction ahead signs

There may be times when "Road Work Ahead" signs are posted but no work is going on. This is because we are legally obligated to post these signs or other applicable warning signs at work zones. Even though there may not be any obvious work activity, or even active work, there may be work you cannot see or the roadway is not in it's original condition or final state after work completion. Areas such as where temporary concrete barrier is still protecting a work area, even during non-work hours, still require warning signs because this is not the normal condition of the roadway. We want to ensure that drivers are aware that they are in a work zone and are alert to any conditions that may be different from normal.

Ramp closure notices

No one likes to find out a ramp is closed when they get to it, so we normally post notices ahead of time for when a ramp will be closed. There is no fixed time limit, but we do use guidance based on traffic, site conditions, and past experience to determine a reasonable advance warning time to alert drivers to an upcoming ramp closure. Short term closures for a few hours or overnight normally only need about 3 days advance notice, and may receive even less notice if there is an urgent or emergency need to close a ramp. Long term closures are scheduled as far in advance as possible, and one to two weeks of advance notice may be required. Long term closures are also usually announced through various media platforms (news, social media, this website, etc.) to get the notice out to as many people as possible.

Advance warning

We try to give drivers as much advance warning as possible so that they can choose to take an alternate route rather than traveling through a work zone and its potential backups. Advance warning signs placement is considered as part of the planning and design and work zones, but we predicting the length of a potential backup is difficult at best, and sometimes impossible. In an effort to alleviate some of these issues, we have started making more use of portable changeable message signs (PCMSs) that we can set up in response to longer than expected backups or at important route decision points to help drivers make route choices. Sometimes we are also able to make use of permanently installed variable message signs (VMS) - the large electronic signs installed overhead on sign structures or bridges - if their location works out. Newer technology is becoming available that will allow us to remotely monitor work zone backups and send real-time information and messages to strategically located PCMSs, and we're looking at how to incorporate this and other emerging technologies.

Quiet lane closures

There may be times when you encounter a lane closure sign, and everyone moves over, and then there is no work or no actual lane closure. This will usually happen when the work zone is being set up or taken down. Many work zones are very labor intensive to set up and take down, taking up to two hours for each depending on the size and complexity. If a driver happens to be traveling through a work zone during these times, crews may have already set up signs but not started setting up devices like cones and barrels, or they may have taken down the devices and haven't made it back to pick up the sigs yet. However, there are occasions where a sign is inadvertently left in place when it is not needed, and we try to respond as quickly as possible when this happens.

Types of signs

Work zones are usually easy to identify by their orange warning signs. Work zones may also use any number and type of conventional road sign when needed, but most warning signs - which are usually black on yellow backgrounds - are replaced with black on orange signs when installed specifically for the work zone. Existing signs that still apply will remain in place and unchanged.

Signs that will often be seen in work zones include:

  • Orange background work zone warning signs
  • Orange background advisory speed signs, used for sharp curves, rough roadways, and other situations where driving at the regular speed limit is not advised.
  • White background regulatory signs. These reflect laws, and include signs like speed limit and traffic fines double signs.
  • Portable Changeable Message Signs (PCMS). These are the trailer mounted electronic signs you may see in advance of a work zone.
  • Permanent Variable Message Signs (VMS). These are the large electronic signs usually installed overhead on highways.
  • Temporary guide and directional signing. These may either be standard colors (white on green background) or temporary colors (black on orange background).
  • Road and ramp closure signs.

Remember that all normal rules of the road still apply in work zones, including compliance with posted signs, and that traffic fines are doubled for infractions in a work zone.

Night work

Everyone hates delays due to work on the highway, but we can't always work at night. Reducing delay may be the only real benefit to working at night, but it is an important one. But there are a lot of drawbacks to working at night, not all construction work can be performed at night, and some work cannot be completed in a single night and spills over into the following morning.

If we can limit our work zone impacts to a reasonable amount of delay for the traveling public, we will conduct work during the day. Here's why:

  • Night work is inherently more dangerous for everyone. Reduced visibility for both workers and drivers make it harder to work safely and harder for drivers to avoid potential hazards. There is also a higher likelihood of impaired drivers at night, either under the influence or even just drowsy.
  • Production is generally slower and quality can suffer because of limited light - even with temporary lighting such as portable light plants.
  • Night work is typically more expensive, as work is slower, more traffic control is needed, artificial lighting is required, and additional protective measures are needed.
  • Some locations have noise restriction ordinances at night, limiting the ability to perform certain noisy work during night hours.

This is just part of what goes into the complex issue of determining when night work is appropriate. We will continue to rely on night work in many of our urban and high volume areas due to the severity of daytime traffic impacts, but there may be times when we just can't avoid daytime work in those areas.

Work vehicles

There can be a lot of vehicles involved in a work zone, and it may look like some aren't really doing anything. Let us assure you that is not the case.

Attenuator trucks save our workers lives. But under normal circumstances, these trucks just sit near the start of the work zone and don't appear to be doing anything. In other cases, we need to bring in multiple crews, or a lot of material in different trucks, and then the crews end up working out on the road on foot. Other times, there may be a mobile operation and they are constantly moving around.

We try to be as efficient as possible and expedite work through the use of specialized equipment that improves our work production. For some larger operations, it may take as many as three additional vehicles to support traffic control and work zone safety.

Bridge inspection closures

All of our bridges require regular inspections. Depending on the extent of a particular inspection, and the equipment necessary to perform the inspection, we may have to close a bridge entirely to complete it. We also may need to close a bridge if there is a major safety concern, such as a collision with the bridge or after an earthquake. Under normal circumstances, in most cases, we are able to perform inspections by only partially closing the roadway.

Work zone training

WSDOT does not hire flaggers or other traffic control workers for private or commercial activities. Our own staff on our work zone crews are trained and certified but only perform work in support of other WSDOT activities such as maintenance. WSDOT employees looking for Flagger or Traffic Control Supervisor (TCS) training should contact their Region Safety Office.

Flaggers and TCS personnel working for private companies are also required to be certified. The Traffic Control Oversight Committee (DOCX 135KB), or TCOC, regulates who may provide training and issue the Washington State Flagging Card and Traffic Control Supervisor (TCS) Card. Please contact John Gancel ( or Steve Haapala ( for information on becoming an authorized training provider or instructor.

Flagger Certification training

Washington State Flagger Certification courses are available at many Community Colleges and through the TCOC approved training providers listed below (State flagging cards from Oregon, Idaho and Montana State flagging cards are also accepted in Washington. 

Traffic Control Supervisor (TCS) training

Successful completion of a three-day Washington State TCS course is required to become certified as a TCS and receive a certification card good for four years. Renewals require a one-day recertification course if taken before your current card expires. There is a 6-month grace period for recertification, but you may not work as a TCS at any time if your card is expired.

Prerequisites for TCS certification are verification of a minimum of 2000 hours of temporary traffic control related work and a current (unexpired) flagging certification from Washington State, Oregon, Idaho, or Montana.

The following groups offer TCOC approved training providers offer Washington TCS certification training:

Slow down – lives are on the line. 

In 2023, speeding continued to be a top reason for work zone crashes.

Even one life lost is too many.

Fatal work zone crashes doubled in 2023 - Washington had 10 fatal work zone crashes on state roads.

It's in EVERYONE’S best interest.

95% of people hurt in work zones are drivers, their passengers or passing pedestrians, not just our road crews.