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Public Roads - November/December 2004

November/December 2004
Issue No:
Vol. 68 No. 3
Publication Number:
Table of Contents

Work Zones That Work

by Carol Keenan

With workers and motorists at jeopardy and motorists frustrated by unexpected delays, the operational perspective of work zone management is the present focus.

This congestion is typical of approaches to work zones and is a frequent cause of motorist dissatisfaction.

Much of the Dwight D. Eisenhower National System of Interstate and Defense Highways is more than 30 years old, and new roads continue to be built, making it a challenge to maintain this constantly expanding infrastructure. Add to the mix limited budgets, more road usage during nonpeak times, road materials lasting only about 30 to 40 years, and the explosion of growth, and it is easy to understand the tremendous undertaking that faces the transportation community in maintaining the highway network.

Understandably, instead of concentrating on new construction, transportation agencies increasingly focus and spend funds on preserving, rehabilitating, and maintaining existing roads. About 13 percent of the National Highway System was under construction during the summer of 2001, with approximately 3,110 work zones. While these work zones are necessary to maintain and upgrade the Nation's aging highway infrastructure, they also reduced capacity by 33,610 kilometers (20,876 miles) of roadway.

At the same time, vehicle travel continues to increase significantly faster than the addition of new miles of roadway. Over the last 20 years, route miles of highway increased approximately 5 percent, while vehicle miles of travel grew by about 79 percent. In economic terms, the demand far exceeds the supply. Work zones further exacerbate the situation because they add to the growing congestion problem. Roadway usage during nonpeak times makes the window to perform roadwork without severely affecting traffic smaller and smaller. Transportation agencies must perform more roadwork under heavier traffic conditions, often in less time.

"The transportation community must achieve a balance between construction needs and the safety and mobility needs of the traveling public," says the Federal Highway Administration's (FHWA) Associate Administrator for Operations Jeff Paniati. "It is important to develop comprehensive mitigation measures that minimize the impacts of work zones and ultimately improve transportation mobility and safety."

Cause for Concern

Given the combined trends of more highway improvement projects and more congestion, the American public is becoming increasingly frustrated with work zone delays. FHWA research shows that the traveling public is demanding increased mobility, while showing less tolerance for delays, increased travel times, and inconveniences resulting from construction-related congestion.

Unlike congestion caused by routine heavy traffic during daily peak travel periods, nonrecurring events generally result in unexpected travel delay and motorist frustration. Work zones accounted for about 10 percent of all delays annually, or 482 million vehicle hours in 1999. As congestion builds approaching work zones and within them, safety degrades, and the crash rate increases. The most frequent type of incidents in work zones are rear-end crashes due to unexpected queuing.

The public's frustration with work zones is evident from the results of a 2000 nationwide survey report by FHWA titled Moving Ahead: The American Public Speaks on Roadways and Transportation in Communities. The report cited work zones as second only to poor traffic flow in causing dissatisfaction. In the survey results, the public indicated that the top three roadway and transportation improvements that would be a "great help" relate to repairs and work zones: 67 percent of the respondents chose more durable pavement materials, 66 percent chose repairs made during nonrush hours, and 52 percent chose reducing repair time. Many travelers indicated a preference for closing roads completely for moderate durations in exchange for long-lasting facilities. The survey responses are a compelling call to action for finding ways to make transportation work zones work better.

Statistics show that work zones, in addition to causing delay, can be dangerous for construction crews and motorists. Work zone fatalities increased nationwide by 17 percent over the last 5 years. In 2003, there were 1,028 fatalities and more than 41,000 injuries that resulted from motor vehicle crashes in work zones. Four out of five people killed were either motorists or passengers.

"Work zone crashes pose tremendous costs to society," says Administrator Mary E. Peters of the Federal Highway Administration (FHWA). "The human cost is the most tragic and the most critical. But there is also the economic cost that results from congestion, unexpected delays, and delayed freight deliveries. One FHWA commitment is to make work zones safer and improve mobility in and around them."

Real-Time Communications For Work Zones

The traveling public has shown substantial capacity for planning around work zones—if they know about them. Motorists want information they can trust, and they want it far enough in advance to make reasonable travel decisions. The challenge for the transportation community is to increase the use of innovative strategies and a policy-driven focus to mitigate the impacts caused by work zones. Current strategies include providing general construction information on Web sites, using innovative construction and contracting strategies, and applying intelligent transportation system (ITS) technologies to improve the performance of work zones.

Accurate, real-time travel information on work zones is essential for time-starved motorists, freight haulers, and tourists. ITS technology provides the underpinning infrastructure for delivering that information continuously and automatically.

"Real-time traffic management and travel information should be an integral part of highway construction," says Paniati. "It should be unacceptable to operate work zones without regard to the customer's need for information and guidance."

As the 511 traveler information telephone service is implemented and becomes more available across the country, detailed information will be accessible for anyone with a phone, enabling motorists to plan for the inconvenience of delays and remain in control of their own schedules. Increasingly, the 511 service is providing the real-time information necessary to choose alternate routes, times of day for travel, or the option to telecommute.

Final Rule on Work Zone Safety and Mobility

The Federal Highway Administration (FHWA) recently updated its regulation that governs traffic safety and mobility in work zones on highways and streets (23 CFR 630 Subpart J). The final rule was published in the Federal Register (69 FR 54562) on September 9, 2004.

The purpose of the update is to address the challenges of more work zones and increased congestion, while ensuring the safety of motorists and construction workers. The changes to the regulation will facilitate comprehensive consideration of the broader safety and mobility impacts of work zones through a project's life cycle and the implementation of strategies that help manage these impacts.

"The new provisions will help State departments of transportation meet current and future challenges in work zone safety and mobility, and serve the needs of the American people," says Scott Battles, FHWA's Work Zone Mobility and Safety Team Leader.

Overview of the New Rule

FHWA broadened the regulation to include the following key features:

  • A State-driven focus that will institutionalize work zone policy, processes, and procedures at the State level.
  • Emphasis on addressing the broader impacts of work zones on travelers and workers by developing transportation management strategies that address traffic safety and control through work zones, and by effective transportation operations and public information and outreach.
  • Emphasis on a partner-driven approach, whereby transportation agencies and FHWA work together improving safety and mobility in and around work zones.

Learn More

The effective date for the new rule is October 12, 2007. For more information, visit or contact a member of the Work Zone Mobility and Safety Team at 202-366-6993 or


This traffic flow indicators map from the Arkansas I–40 Web site provides real-time information to the traveling public.

Another method for communicating information is Web sites, which also can provide traffic flow maps with the location of congestion in real time so motorists can better plan their trips. A review of State road closure and construction Web sites reveals that project location, purpose, and overall duration are likely to be posted early in the planning process, but the posting is unlikely to be updated often. A current shortcoming: information of greatest interest to the traveling public, such as number of lanes closed, times of closure, and estimated delay, is reported only about 6 percent of the time.

States are refining their use of information posted to project Web sites. "We learned that people are interested in the most updated information," says New Jersey Commissioner of Transportation John F. "Jack" Lettiere. New Jersey plans to update a Web site for a project extending Route 18 into New Brunswick, NJ. The department of transportation (DOT) and the New Jersey Turnpike Authority Traffic Operations Center plan to post realtime, current information within 4 minutes of any change. Commenting on the use of real-time information, Lettiere says, "We've done it on other projects, but this one is much more complex." The Web site and real-time traffic information would help commuters and students at nearby Rutgers, The State University of New Jersey, deal with this construction project.

Similarly, the North Carolina DOT used ITS technologies in a number of interstate work zones to manage traffic. Sensors were used to calculate either delay or travel time. That information then was used to display messages on variable message signs (VMS) and/or Web sites. For example, on I-95 outside Fayetteville, when delay was greater than a preset threshold, estimated delay and an alternate route were displayed on VMS. This allowed motorists to choose to use the alternate route and reduce congestion and queuing.

In 2000, the Arkansas State Highway and Transportation Department (AHTD) reconstructed 5 kilometers (3 miles) of concrete pavement on I-40 near its intersection with I-55 in West Memphis, AR. The work zone area began near a bridge across the Mississippi River to Memphis, TN, and abutted a Tennessee work zone on the bridge. Officials from AHTD believed they needed to go beyond traditional traffic control in addressing the impact of the reconstruction project and looked for ways to communicate with the public in both Arkansas and Tennessee about specific delays to expect from the construction.

According to AHTD Chief Engineer Robert Walters in FHWA's Intelligent Transportation Systems in Work Zones: A Cross-Cutting Study report, "Prior to reaching the construction area, motorists have a choice of routes to take, either I-40 or I-55." An automated information system acquired data on traffic conditions approaching the work zone and processed that information to inform travelers of the length of any queues ahead as they approached the work zone on I-40. To enable drivers to choose alternate routes that would reduce delay, real-time information was displayed on dynamic message signs strategically placed before key alternate routes and updated automatically by the system as conditions changed.

"The ITS advised travelers of any problems on the routes and helped them make the most informed decision possible at the time," says Walters. "Local residents are familiar with alternate routes, and the ITS information helped them readily decide which route to take. Motorists traveling cross-county, however, may not readily know alternate route options, but the ITS [communicated] what to expect in terms of traffic backups and delays."

Highway advisory radio was another communications tool, which broadcast current traffic condition information to listeners. Not only did this project enhance relationships with residents by keeping them informed, but also it helped improve the interstate relationship with neighboring Tennessee and residents who were affected by the work zone west of Memphis just over the border in Arkansas.

The planning in Arkansas for traveler information may be the exception to the rule when it comes to ITS use. Minor applications of ITS technologies to improve work zone performance are typical. As in Arkansas, however, ITS use in work zones can go well beyond dynamic message signs. It can integrate a variety of traffic monitoring, reporting, and management systems to improve system operations.

ITS also provides a unique solution to controlling traffic at merge points. State-of-the-art dynamic lane merge systems are becoming increasingly popular because they provide a real-time solution to aggressive driving and safety problems at work zone tapers. Industry is making strides in packaging and tailoring technologies to work zone situations, and ITS is becoming more widely accepted as providing real, sometimes off-the-shelf, solutions to mitigate work zone impacts.

Road Closure Strategies

Growth in the number of improvement projects on roadways that are open to traffic is a concern to highway professionals. Increasingly high traffic volumes on many highways make it difficult to perform work operations in or near travel lanes during much of the day because of the risk for workers and the traveling public. In response, scheduling highway work for offpeak periods has become commonplace. Nighttime construction reduces the impact to peak-period traffic, while accomplishing necessary roadway improvements.

Crews work without interruption on a closed section of I–84 (Banfield Freeway) in Portland, OR.

Nighttime construction techniques are fairly common in the United States and abroad, with more than one-quarter of work zones primarily active at night. This scheduling option can be adopted by agencies as a means to increase the efficiency of peak hour travel. However, emphasis should be placed on special considerations for worker and traveler safety in nighttime work zones such as enhanced traffic control devices, visibility of works, visibility of work vehicles, controlling speed, increasing driver awareness, providing glare-free illumination; and accommodating pedestrians. (See "Improving Traffic Control for Night Work Zones" for information about how to set up a safe nighttime work zone.)

Other States such as Delaware, Indiana, Kentucky, Michigan, Ohio, Oregon, and Washington are using a different strategy that was once considered unthinkable—closing roads completely. Full road closure alleviates the potential for long-term traffic congestion and improves safety by reducing crashes and other incidents. In the full-closure strategy, the roadway is closed, traffic rerouted, and the contractor given full access to the roadway. Full closure strategies are used to help reduce the construction period, improve quality, increase safety by reducing traveler exposure to complex work zones, and separate the road worker from the hazard of freeway traffic.

Although closing a road completely may appear to be a drastic measure, the benefits may outweigh the possible inconvenience and complications when used in appropriate situations. "Under the appropriate conditions," says Ohio DOT Director Gordon Proctor, "a full closure can be an effective way to complete projects faster and improve safety for highway workers and motorists."

In an applicable situation with adequate alternate routes available, a solid traffic management plan, and a public outreach campaign, full closure can reduce overall project duration significantly and is a viable alternative to traditional part-width reconstruction. ODOT recently completed a full-closure project on I-670 in Columbus. Originally, ODOT allocated 4 years for the project. Full closure enabled the contractor to finish the project in 18 months, a 63-percent time reduction over predicted duration. ODOT realized an estimated $8 to $10 million cost savings, greater workspace, increased productivity, and positive public sentiment.

In a project dubbed "Hyperfix 65/ 70," the Indiana DOT successfully used full closure in 2003 to expedite rehabilitation of I-65/70 in Indianapolis. (See PUBLIC ROADS March/ April 2004.) What INDOT estimated would take 180 days using traditional part-width construction was completed in 55 days using full closure. INDOT estimated that traditional construction would have added $1 million per day in lost productive time to highway users.

Full closure is not the solution to every problem, but in a 2003 report Full Road Closure for Work Zone Operations, FHWA concluded that full road closures have become a successful tool on deteriorating roads for reducing the overall impact of work zones. The full-closure methodology is one that many agencies are considering for required road maintenance and rehabilitation. In many cases, the benefits far outweigh the costs as many full-closure projects have resulted in increased productivity, reduced project duration, enhanced safety, and lowered costs. The study found that for the six projects examined, project duration was reduced by an average of 76 percent compared with traditional, part-width construction.

In addition to full road closures, a number of other alternate closure strategies are possible. For example, some agencies and contractors use a full-closure approach for an extended period but not for the entire project, while others perform full-closure operations on weekends or at night when traffic levels are lower. Several agencies have adopted the transportation community's popular slogan, "Get in! Get out! Stay Out!" as a reminder of what needs to be done to meet the expectations of today's public.

Full-Closure Tips

The following guidance is from Full Road Closure for Work Zone Operations: A Cross-Cutting Study published in August 2003. Additional information is available online at:

State highway agencies have used full road closure successfully on a variety of project types ranging from full-depth reconstruction to bridge joint replacement with guardrail enhancements. The projects examined during this research effort had varying characteristics and reasons for using full road closure, while achieving similar positive results. Project personnel interviewed felt that full road closure was able to improve the road rehabilitation process, creating efficiencies that reduced project duration and in some cases overall costs, while improving safety. A consistent theme, heard during interviews with project personnel, was the positive public sentiment that resulted from the use of full road closure.

Why Use Full Road Closure?

Full road closure has the potential to:

  • Expedite project completion
  • Reduce the impact of construction on travelers
  • Maximize workspace available to the contractor and increase productivity
  • Reduce overall congestion resulting from construction
  • Improve safety for workers and travelers
  • Reduce crashes in some cases
  • Result in a smoother roadway
  • Improve public sentiment

Benefits of Full Road Closure

The six projects examined for this study experienced numerous benefits as a result of using a full-closure approach.

  • All projects in this study reported a reduction in project duration.
  • Two projects realized significant estimated cost savings.
  • For five projects, project personnel cited traveler and worker safety as a benefit.
  • Three projects reported a better quality product.
  • All projects reported that public sentiment was positive.
  • The increased workspace and flexibility in project staging that are offered by full closures often led to greater efficiency.
  • Project personnel felt that worker productivity improved due to less distraction from traffic.
  • All project sites noted that the impact of construction on travelers was reduced.

Considerations Associated With Full Road Closure

  • City/county agencies and personnel often need to be convinced of the feasibility of implementing a full closure strategy and the potential benefits that can be realized.
  • Full-closure projects typically are done on an accelerated schedule. Contractor and supplier ability to provide adequate amounts of resources should be assessed prior to letting the project.
  • Meeting the project completion deadline is particularly important when using full-closure since this is often highly publicized as the date when the road will reopen. Therefore full-closure projects may carry additional deadline pressure for those involved.
  • Full-closure impacts on businesses can be a factor and need to be considered in the planning process.
  • Full-closure projects often are scheduled on a 24-hour work basis, so there is potential for impacts to local residents, including noise and light pollution.
  • Increases to traffic densities on alternate routes must be assessed, planned for, and managed. Improvements or operational enhancements to alternate routes may be required.

Lessons Learned

  • The public outreach component was a key factor in the success of these projects.
  • Lead-time is needed for increased planning and outreach to stakeholders with regard to the potential effects of road closures.
  • Adequate alternate routes are a critical factor in pursuing a full road closure approach. For the study sites, congestion was often less than expected, as a result of good information dissemination. Two sites related that after about 2 weeks traffic redistributed on its own and balanced the increased load on the network, at which time a fair assessment of overall traffic flow could be made.
  • A solid traffic management plan, including adequate signage about alternate routes, is vital.

Worker Protection Strategies

On the morning of May 9, 2003, a five-person work crew was filling potholes on the Duke Street Bridge over I-395 in Virginia. A motorist struck the rear of another vehicle slowing in the work zone, lost control, and entered a right lane work zone. A member of the crew was hit and thrown off the overpass onto I-395 northbound, where several vehicles fatally struck him.

A movable barrier system like this one can separate traffic from workers and allow for enough capacity during peak periods.

Incidents like this one in Virginia indicate the importance of balancing the need for traveler mobility through work zones and the need for adequate space, lighting, and the work environment required to get the job done safely for the public and construction workers. Positive protection—the use of devices such as barrier separations that contain and redirect vehicles—can reduce the risk to workers and travelers from vehicle intrusions. Use of truck mounted intrusion alarms for the work site can help as well.

With proper planning and adequate specifications, other mitigation strategies also provide dramatic benefits. The continually changing nature of work zones and the fact that safe speed depends on roadway conditions make variable speed limits (VSL) in work zones particularly useful. A field demonstration was conducted in Michigan with promising results. An additional field test is planned for a Maryland work zone. The projects analyze variations in speed and accompanying driver behavior (such as abruptly hitting the brakes). The VSL technology is used to determine appropriate speeds for work zones and changes the speed limits when conditions change, such as traffic flow, traffic speed, weather, and the nature of the roadwork. The technology communicates the speed change to drivers using dynamic speed signs mounted on trailers. Varying the posted speed limits as the conditions in the work zone change should result in increased credibility of speed limits, greater speed compliance, improved safety, and improved compliance.

Quick Construction

On March 26, 2004, a tanker truck carrying 45,420 liters (12,000 gallons) of fuel oil crashed in Connecticut and ignited a ferocious fire. A bridge on I-95 melted, threatening to cripple one of the Northeast's most important transportation corridors. Tens of thousands of lives were affected. Motorists needed to find alternatives. New technologies and a great deal of hard work by the Connecticut DOT and contractors enabled traffic to roll again in only a few days. ConnDOT used the latest in "quick construction" technology to fast-track repairs. In this case, a prefabricated steel bridge was assembled and shipped to the site, then lifted into place by crews working overtime.

Not only is work zone safety a concern in the United States, the United Kingdom used this photo of a worker in a public campaign to increase awareness of work zone safety

Workers using precast pavements that fit together, quick-curing concretes, and machines that ensure pavement is smooth before it dries are additional examples of ways to shorten highway construction times. (See the May/June 2004 issue of PUBLIC ROADS for more details about precast concrete and other methods for shortening the construction cycle.)

Innovative Contracting

Since the 1990s, FHWA has been supporting the use of innovative contracting methods. No longer is cost the sole criterion that determines the winning bid. FHWA research indicates that construction projects once tolerated as a fact of life must now provide timely delivery of a quality project with limited road user and social impact costs. Contracting procedures are used to reduce highway construction project times. Benefits from reduced project times include reduced traffic delays and associated costs, fewer crashes and injuries in and around work zones, and lower capital costs for maintaining traffic.

Innovative contracting techniques such as A+B bidding is a cost-plus time bidding procedure that selects the low bidder based on a monetary combination of contract bid items (A) and the time (B) needed to complete the project or a critical portion of the project. The intent of this kind of bidding is to provide an incentive for the contractor to minimize delivery time for high-priority and congested roadways by offering incentives for early completion and disincentives for late completion. This strategy is best used when traffic inconvenience and delays need to be held to a minimum. The New York State DOT found that contractors bid, on average, 32 percent below NYSDOT's estimated time and completed the work ahead of schedule.

When variable speed limit signs such as this one are used to alert motorists to slowed or stopped traffic, the incidence of rear-end collisions occurring in work zones is reduced.

Incentive/disincentive contracting provides an opportunity for an agency to enhance delivery through improved accountability. Lane rental, another form of innovative contracting by which a contractor is charged a fee for occupying lanes or the shoulder to do contract work provides an incentive to minimize the duration of a lane closure and keep traffic moving.

Work Zone Analysis Tool—QuickZone

Providing transportation partners with an analytical tool to assess and manage work zone impacts is another means of fostering improvements. A traffic impact analysis tool called QuickZone enables practitioners to quantify the queue length and user delay caused by work zones. After experiencing significant delays and frustrations at work zones on I-80, Pennsylvania DOT District 10 engineers used QuickZone to model future work zone configurations before implementing them. The PENNDOT engineers were able to select work zone configurations and construction schedules that met project needs while minimizing impacts to the traveling public. They identified the delay impacts of alternate phasing plans and alternate project staging (day versus night, peak versus offpeak, summer versus winter). QuickZone, which supports tradeoff analyses between the costs of construction versus delays, can be used to help establish work completion incentives and to assess the impacts of travel demand measures and other mitigation strategies.

This warning sign alerts motorists to a work zone ahead.

From the reduced number of complaints and the comparatively shorter length of time motorists experienced delays in the work zone, PENNDOT believes the effort was a success. "Based on what we saw occur on the interstate last year and compared to this year," says PENNDOT District 10 Executive Richard H. Hogg, P.E., describing the State's before-and-after experiences with QuickZone, "the improvements for our customers—the traveling public—are significant."

In early 2005, a new version of QuickZone is planned for release (see "Resources"). Improvements to this analysis tool will include a graphical user interface for network building; improved two-way, one-lane operations modeling (for example, flagger operations); improved flexibility to model more complex projects; enhanced detour modeling; and the ability to track, graph, and analyze a wider variety of performance measures than was previously possible.

The use of night construction, as shown here, is one measure to reduce travel delays from work zones.

Making Work Zones Work Better

Business as usual is not acceptable to motorists. The problems are growing and are costly in terms of lives, time, and money. Real solutions will come from a fundamental change in the way projects are planned, estimated, designed, bid, and finally constructed. Communicating to the traveler, reducing traveler exposure, and influencing traveler behavior are major actions that, if implemented, could result in reduced congestion and crashes in and around work zones. Agencies are moving toward real-time traffic management and travel information as an integral part of highway operations, in addition to incorporating the customer need for information and guidance.

As successful new technologies are deployed, communities will see the benefits of roads that open faster, require less repair work in the future, and provide safer, smoother rides at less cost.


Some of the resources available to help customers and partners make work zones work better include the following:

  • The Accelerated Construction Technology Transfer (ACTT) program promotes the use of innovative technologies and techniques to accelerate the construction of major highway projects or corridor improvements using a multidisciplinary team approach. Information on this program is available at or by contacting Jim Sorenson at 202–366–1333 or Dan Sanayi at 202–493–0551.
  • The Making Work Zones Work Better Workshops Series shares information on new and emerging technologies and highlights operational opportunities and constraints by local agencies. This practitioner tool provides an open forum for discussion and information sharing to enhance the body of work zone knowledge and improve future work zone programs. Information on the workshops is available at or by contacting Daniel Grate, Jr. at 404–562–3912.
  • QuickZone is a traffic impact analysis tool that enables practitioners to quantify the queue length and user delay caused by work zones. Additional information on QuickZone is available at or by contacting Deborah Curtis at 202–493–3267. QuickZone 2.0 is planned to be released in early 2005 and will be a free update for users with a valid license for QuickZone 1.0.


Carol Keenan is a transportation specialist in FHWA's Office of Transportation Operations in Washington, DC. As a member of the Work Zone Mobility and Safety Team, she is responsible for work zone outreach and education. Keenan holds a bachelor's degree in logistics from Penn State and has 18 years of experience with USDOT. Prior to joining FHWA, she worked in both the Federal Aviation Administration and the Federal Motor Carrier Safety Administration.