Ensuring safety in road work zones
With the deterioration of the nation’s streets and highways, road construction and maintenance have become important components of an area’s public works scheme. Highway maintenance and construction jobs, however, are among the most dangerous for local government employees.
In fact, in each of the past four years, about 775 people were killed in highway work zones, according to the Washington, D.C.-based National Highway Traffic Safety Administration (NHTSA). A majority of those accidents occurred at night, when many crews do most of their work to avoid disrupting daytime traffic, and most were the result of excessive speeding or inattention by motorists. Figures from NHTSA and the Federal Highway Administration (FHWA) also show about 24,000 injury crashes annually in work zones.
In response, federal regulators are working to fine-tune work zone guidelines and improve the safety of traffic control devices, while many states have cracked down on motorists who drive recklessly near work zones. Meanwhile, better training, advances in technology and consumer education campaigns all have played a role in improving safety for road construction workers.
Multi-faceted response Many of the ongoing safety initiatives are backed by the federal and state governments. At the local level, no national standard manual exists for urban road work zones, according to Seattle-based consultant John Logan. Because of that, cities like Phoenix, Seattle and Salt Lake City have developed their own.
“The federal guidelines do a pretty good job with high-speed [situations],” says Logan, a former traffic and planning engineer with the King County (Wash.) Department of Public Works. “But more work needs to be done for the urban and suburban areas.”
Phoenix came out with its “Traffic Barricade Manual” in 1961 and has revised it eight times, says Mike Frisbie, traffic engineer supervisor with the city’s streets and transportation department. The 95-page manual includes 32 diagrams and a four-page insert that describes acceptable and unacceptable conditions for signs, pylons and related gear that is susceptible to fading, scratching and other damage. (The manual’s insert was produced by the American Traffic Safety Services Association (ATSSA), Fredericksburg, Va.) Frisbie says details on setting up work zones in major signalized intersections separate the Phoenix manual from the federal “Manual on Uniform Traffic Control Devices (MUTCD).”
For cities that have not developed their own work zone safety manuals, the MUTCD is a good starting point, according to Anthony Giancola, executive director of the National Association of County Engineers, Washington, D.C. “That’s our bible,” he says.
The MUTCD explains in detail how cones, barriers and other traffic control devices such as electronic signals should be erected and configured. Originally published by the FHWA in 1927, the MUTCD has undergone numerous revisions. Part 6, which covers work zones, was last updated in 1993, according to Rudy Umbs, chief of the FHWA’s Safety Design & Operations Division. Further revisions are expected to be published in 2001.
Giancola says some communities are less likely than others to abide by the MUTCD, either because they want to save time in completing road repairs or because they do not own the manual.
“There are still folks out there who are not aware of the manual, believe it or not,” he says. “One of the biggest problems we have is reminding people that even just fixing a pothole does require work zone provisions.” That is particularly true, he adds, on roads that are hilly or full of curves.
“Cities generally don’t have a lot of high-speed situations,” notes Henry Pearson, manager of highway planning and design for Carter & Burgess, a Fort Worth, Texas-based engineering and contracting firm. Because of that, he says, there is a temptation to cut corners when it comes to setting up work zone barriers and signage around minor jobs that are not expected to take long.
While local street departments might get away with shortcuts on small projects, they had better use plenty of foresight for larger projects, Pearson says. “Managing traffic in a work zone often includes temporarily redirecting lanes or establishing detours. That means you are changing what motorists have grown accustomed to, so you have to be very careful to get their attention,” he says. Ideally, according to Pearson, traffic engineers planning to set up a detour should first drive around to check out the lay of the land and determine whether pedestrian traffic will be affected.
In addition to a detour route, a road’s speed limit and terrain, the neighborhood’s population density and provisions for an emergency vehicle route must be evaluated, Pearson says. Crews also must remember that work zones and detours, once established, need to be maintained.
Moreover, in cities with a high concentration of older drivers, brighter signage and simpler detours are advisable, according to a Transportation Research Board study. (The study examined how diminished night vision and slower cognitive abilities increase accident rates for people older than 65.)
Increased regulations Since the Highway Safety Act of 1966, regulations affecting work zones have increased, but some of them are not contained in the MUTCD. Since the mid-1960s, “We’ve seen a definite shift in the sizes of vehicles,” Umbs says. “We started to do more testing, and we set up more criteria.”
As a result, now there is more rigorous testing of barriers, signs and other work zone devices for crash-worthiness. The National Cooperative Highway Research Program (NCHRP) has been formulating more stringent crash-worthiness standards with which manufacturers of traffic control devices must comply. The standards in NCHRP Report 350 encompass a wider range of devices than did those of its predecessor, NCHRP-230. NCHRP-350 covers four categories of traffic control devices: * Category I includes traffic cones, tubular markers, single-piece drums and delineators. The new standards went into effect on Oct. 1.
* Category II includes plastic barricades, vertical panel assemblies, intrusion alarms and portable sign supports. Those devices must meet NCHRP-350 standards beginning Oct. 1, 2000. Street and highway departments may find of particular interest a statement in the FHWA memo regarding NCHRP-350: “We believe it is important to note that failures of certain (Category II) devices that are in common use have occurred during crash testing.”
* Category III includes hardware that is expected to cause significant velocity changes or other potentially harmful reactions to impacting vehicles. It includes some types of barriers, fixed sign supports, truck-mounted attenuators, crash cushions and other work zone devices not meeting the definitions of the first two categories. Oct. 1 was the compliance deadline.
* Category IV includes portable or trailer-mounted devices such as arrow displays, temporary traffic signals, area lighting supports and portable, changeable message signs. After the Oct. 1, 2002, compliance date, Category IV devices may not be used unless they are placed behind crashworthy barriers or shielded with crash cushions or truck-mounted attenuators.
The standards mandate that National Highway System projects use devices meeting NCHRP-350 crash-worthiness requirements. State and local transportation departments that fail to comply could risk losing federal funds. FHWA is allowing a grace period for some Category III devices like portable concrete barriers that meet the previous standards. Such devices, if they already are in use, can be phased out as they complete their normal service lives.
Product improvements As regulators have intensified their focus on work zone devices and guidelines, manufacturers have responded by improving the safety of their products. “There are better markings all the way around,” says Don Brown, president of Los Angeles-based Arrow Sign. Greater use of bright plastics (as opposed to concrete), improved fluorescence on barriers and signs, and reflective paint for lane markings are among the improvements, he says.
Fluorescent reflective products were not widely used in road construction applications until recently because the fluorescence tended to fade quickly. However, new technology such as diamond-grade reflective sheeting makes the fluorescence last much longer. The sheeting uses prismatic “micro-cubes” rather than glass beads to provide reflectivity at all angles.
Intelligent Transportation Systems (ITS) technology also is playing a greater role in ensuring work zone safety. Under the auspices of the FHWA’s Strategic Highway Research Program, some states have experimented with devices such as intrusion alarms that sound when an unauthorized vehicle enters a work zone area. They also are using queue detectors, which project an infrared beam across a roadway to determine whether a line of vehicles has formed behind a construction sight. When a line forms, a signal can then be transmitted to electronic variable message signs to inform motorists of the hazards ahead. The DOTs in Minnesota and Maryland also have monitored passing vehicles with Doppler radar.
Efforts also are under way to employ automated machinery to reduce human exposure to injury. Several states, Minnesota included, have experimented with a prototype, remotely driven “shadow” vehicle to bring up the rear of construction zones. Driver-occupied shadow vehicles, which serve as moving barriers between traffic and mobile work crews, are vulnerable to rear-end collisions.
In 1990, a shadow vehicle driver for the Minnesota Department of Transportation (MDOT) was paralyzed when a semi-truck hit his vehicle – an accident that may cost MDOT millions of dollars in worker’s compensation. It is no surprise, then, that the department came up with the idea for a remotely driven shadow vehicle and lent a dump truck to the Strategic Highway Research Program for testing.
After the program achieved satisfactory test results, MDOT helped a nearby company, Red Wing, Minn.-based Safety Technologies, develop a kit to convert trucks to remote operation for $35,000. The company currently is retrofitting a truck for the California Department of Transportation, says company spokesman Chuck Fanslow. Each remotely driven vehicle is equipped with a collision-avoidance system to ensure that it will automatically stop if something gets in its path.
For motorists who are willing to spend their own money on reducing the chances of a work zone accident, Fla.-based Safety Warning System makes transmitters and receivers that provide a synthesized voice or other warning to alert the driver to a construction zone ahead. The transmitters are installed on DOT work trucks or elsewhere on road construction sites, and their signals are picked up by windshield- or dashboard-mounted receivers or specially equipped radar detectors.
On the legislative front As manufacturers hone their technologies and seek to improve work zone devices, and as regulations deal with safety aspects of the products, many states are using legislation and law enforcement to deal with the human element of work zone accidents – drivers. So far, 36 states have enacted laws that impose stiff fines for moving violations in work zones, according to the Washington, D.C.-based National Work Zone Safety Information Clearinghouse. An Oregonlaw, for example, calls for a fine of up to $5,000 or a year in jail for “reckless endangerment of highway workers” or “refusing to obey a flagger.”
In addition, many states are committed to thoroughly studying, analyzing and responding to the causes of work zone accidents. For example, in 1994, the Washington state legislature began to attack the problem by appropriating funds for such things as truck-mounted attenuators, water-filled barriers, changeable message signs and intrusion alarms. Washington also mandates that workers be visible to motorists for 1,500 to 2,000 feet (as opposed to 1,000 feet required by the federal government). The state requires the workers to wear hard hats and orange vests at all times. (At night they also must wear white coveralls underneath highly reflective orange vests.)
Just as laws and enforcement vary with respect to motorists, so does the way authorities treat contractors, state DOTs and other government road crews that violate work zone guidelines. “There’s a lack of uniform enforcement,” says David McKee, director of product marketing and development for the ATSSA. “Some states make a pretty good effort at that; other states need to pay it more attention.” Sam Arnold, president of Las Vegas-based Guardian Safety Barrier, adds, “There’s a lot of ‘looking the other way’ (with regard to violations).”
In any case, TEA 21, the federal transportation bill passed several months ago, requires FHWA to study the technologies and methods being used to enhance work zone safety, streamline construction and improve traffic capacity. The agency will examine what constitutes sufficient separation distances between traffic, equipment and workers. FHWA is scheduled to complete the study within 18 months.
Since ISTEA was enacted in 1991, the federal government has allocated money toward the National Work Zone Safety Program, which is intended to protect workers and develop uniform accident reporting for fatalities and injuries. The program’s four elements are standardization, compliance, evaluation and implementation.
The program offers training for matters such as work zone safety inspections; traffic control design and operations; and work zone safety for rural highways. As part of the program, the National Safety Council offers a flagger training course, and ATSSA offers classes covering topics such as pavement marking techniques, inspections and work site traffic supervision.
In the area of standardization, FHWA is working with the American National Standards Institute to develop a uniform work zone definition. In the absence of such a definition, statistics on city and county work zone accidents are difficult to come by. States vary in how they define a “work zone,” and no uniform reporting procedures exist.
Still, regardless of how well-trained workers are, or how sophisticated the technology is to make their work zones safer, an informed public is essential. To that end, numerous educational campaigns are under way to increase driver knowledge of work zone dangers to reduce the likelihood of crashes.
One of the largest campaigns to improve work zone safety involves the FHWA and 21 state departments of transportation. “Get the picture; listen to the signs,” is a multimedia outreach program featuring three-dimensional animation in two 30-second television ads; three 60-second radio ads; and written materials. Each ad is designed so that individual DOTs can customize them by adding their own logos and tag lines.
Local governments seeking additional work zone accident statistics and information regarding laws, products, regulations, research and training can find them on the Internet. The home page of the National Work Zone Safety Information Clearinghouse, a cooperative venture between FHWA and the Washington, D.C.-based American Road & Transportation Builders Association, is especially especially detailed. The clearinghouse home page can be accessed at http://wzsafety.tamu.edu; by e-mail, [email protected]; or by phone (888) 447-5556. (More web sites are listed on page 26).
Since the late 1980s, the New Hampshire Department of Transportation (NHDOT) has been widening and resurfacing several miles of the F.E. Everett Turnpike, which runs through Nashua in the south-central part of the state. Using temporary panel bridges for intersecting roads, the department is preserving close-to-normal traffic volume and speed during the project.
As part of its work, NHDOT is upgrading merge areas and building a new collector/distributor road. Overpasses at four exits were dismantled to make room for the wider road, as was one railroad bridge.
NHDOT routinely uses panel bridges as an affordable way to set up temporary crossings over construction zones. After a job is done, the parts can be disassembled and trucked away to the next job site.
During the turnpike project, trucks shipped the components, purchased from Acrow Corp. of America, Carlstadt, N.J., to the work site. The 10-foot segments were assembled and put in place by a crane. Pavement then was put down atop the metal decking.
The panel bridges being used in the turnpike project range in length from about 140 feet to 250 feet and have the same vehicle capacity as the permanent structures they replaced, according to Jim Moore, administrator of NHDOT’s Bureau of Bridge Design. The longest bridge required a temporary pier to be erected in the median of the turnpike. Each of the temporary bridges took about a month to erect, with much of the work being done at night. They will remain in place until permanent bridges are constructed within the next year.
More than 20 years ago, NHDOT began purchasing the panel bridge components, which consist of pre-fabricated trusses, floor beams and decking. “We have a pretty vast inventory of components and have used them a number of times for bridge replacement projects throughout the state,” says Turnpike Administrator Harvey Goodwin. NHDOT often lends the components to contractors to keep project costs down.
El Nio captured the nation’s headlines last winter when its storms lashed California, causing flooding that posed considerable hardship to homeowners and farmers. The California Office of Emergency Services in Sacramento estimates that El Nio storms caused more than $500 million in property damage across the state.
Damage estimates to the state highway system alone are at $40 million and climbing. The crux of the problem is potholes, which are formed when excess water seeps into cracks in asphalt, softening the sub-base and making it easier for the wear and tear of traffic to break up the pavement.
“In my opinion, this has been the worst season we’ve had for potholes,” says Richard Barner, senior highway maintenance worker with the Sacramento County Public Works Agency. “Combined with the cumulative effects of the last three years of above-average precipitation, we have more than double our normal amount of potholes.”
Despite the fact that meteorologists had been predicting the phenomenon for several years, some of California’s public works agencies took a reactive approach to El Nio. Sacramento County, however, decided that the best defense was a good offense and began preparing for the worst early last year, according to Don Gibson, a highway maintenance superintendent with the public works agency.
Late last year, the agency’s fleet featured four open-bed patch trucks, four enclosed-bed patch trucks and one air-injected patching trailer. To improve its versatility, the agency purchased an RA-300 air-injected spray patcher from Rosco Manufacturing, Madison, S.D., and trained three people to operate it.
One person can operate the machine, which makes it easier for the agency to schedule nighttime repairs on roads with heavy daytime traffic. “We’re using it every day,” Gibson says, adding that the agency plans to purchase another one next year. The machine enables the agency to use fewer employees and repair potholes in less time since there is no need to rake or compact the patch material.
Operation of the spray patcher is fairly easy. The operator positions the truck behind the pothole to be repaired. Next, he uses a joystick to position the one-piece, double-acting boom over the pothole. Once that is in position, a high-volume blower cleans out loose rock and debris.
Using the same nozzle as he used for the blower, the operator coats the hole with hot asphalt, which seals the area to be patched and prevents water from penetrating the repair. Next, with the push of a button, aggregate and hot asphalt are combined with the forced air to fill the hole. Finally, the valve controlling the hot asphalt is turned off, and a top coat of aggregate is applied.
Finding potholes is not a problem. “We just established a pothole hotline to encourage the public to report potholes and to keep up with the increased amount of damage,” Barner says. “Also, our department supervisors report on potholes as they check the roads during the day.”