Use Best Practices for Low Volume Road Flagging
Neal Carboneau of the Transportation Training Institute shares some best practices of meeting the requirements of the Manual of Uniform Traffic Control Devices by the U.S. Department of Transportation and keeping your staff safe on the job.
Keeping your staff safe on the job site is a constant concern. To do so, contractors have their own plans in place to make safety a priority, beyond what is required by the federal government.
As part of the Code of Federal Regulations, the Manual of Uniform Traffic Control Devices outlines minimum requirements that contractors must follow when setting up a strategy to manage motorists that will need to be safely guided through the work site.
You know from experience, though, that the safety measures for every work zone are different. Traffic volume, physical restrictions, weather and time of day are all factors for every work zone safety plan. What we may not think about as often as we should are flagging operations along low volume roads with average annual daily traffic of fewer than 400 vehicles (excluding freeways, expressways, interchange ramps, freeway service roads, state highway systems and residential streets, in most states).
Less traffic volume doesn’t necessarily make a job site safer. In fact, low volume roads present a number of unique challenges, including hills, curves and vegetation and the potential for harvest operations overlapping with road work.
In March of 2015, with the Workzone Safety Consortium, Transportation Training Institute Founder Neal Carboneau helped create a document to troubleshoot some common challenges workers may face at low volume job sites, provide solutions that fit within the code and suggest considerations to improve safety for motorists and workers.
“The guidance documents serve as commentary and provide suggestions for organizations to not only meet, but exceed the minimum requirements of the code in an effort to reduce the number and severity of incidents in work zones,” Carboneau said. “It provides guidance and further explanations of the intent of the MUTCD while recording traditional methods used to protect road workers and motorists.”
1) Address site conditions.
Site conditions can include hills and curves, obstruction of visibility and working room due to vegetation or rocky terrain, and driver and worker distractions. Although 400 Annual Average Daily Traffic might seem like a small number, Carboneau said even small numbers can represent many vehicles per hour, “which still presents a challenge for organizations performing work on the road to address.”
2) Establish visibility and stopping sight distance.
“The goal is to give motorists plenty of warning, or advance notice, of the work,” Carboneau said. To do so, he said it’s important to get their attention where there is good sight distance, and control them through challenging areas. Carboneau said it’s also important to recognize conditions that could impact visibility, such as glare from the sun at dusk or dawn, glare from artificial lighting or headlights during nighttime operation, and dust from traffic on a gravel road.
He said speed is also a factor. “Stopping sight distance, or the amount of time it takes a motorist to react and bring their vehicle to a stop is not only about seeing the condition that prompts them to make a decision,” Carboneau said, “but also how fast they are going at the time as stopping sight distance is a function of the speed of the motorist.” (See Sidebar A.)
3) Reduce changes or challenges for motorists.
This can include planning operations, such as choosing the time of day that would allow you to avoid certain situations, such as motorists driving into the glare from the sun or experiencing higher traffic volumes. Reducing challenges for motorists can also include the layout of temporary traffic control and selection of devices to fulfill special needs, such as cones, barrels, signs, arrow boards or even portable rumble strips.
“Use of portable radar speed signs are becoming more common in larger scale temporary traffic control areas,” Carboneau said, “but the effectiveness is evidenced by their use in school zones, to get a motorist’s attention and slow them down.”
4) Choose the right type of flagging or alternate control.
“The MUTCD has a number of ‘typical applications’ which provide a foundation on which a temporary traffic control plan should be based,” Carboneau said. “This document provides the reader with examples of the types of operations and conditions that they deal with regularly and which ‘typical applications’ might be better suited for those situations.”
This not only is effective but it’s also efficient, Carboneau said.
“We don’t have unlimited budgets,” he said. “We need to use engineering principles to provide safe, efficient and effective temporary traffic control.”
Carboneau said an example of this is typical application 11 from the MUTCD, which allows the use of a yield sign in lieu of flaggers. This method allows motorists to self-regulate, reduces the exposure to flaggers and frees up flaggers for other operations. Another option is using a single flagger, but this option also comes with unique challenges and specific requirements.
“The guidance goes on to provide alternatives for use of flaggers with mobile operations as well as the use of mobile operations alone, which can provide some options in certain circumstances,” Carboneau said.
4) Ensure safe behavior by flaggers.
“Worker distraction is a problem for employers just as motorist distraction is,” Carboneau said. “Portable music devices, reading materials, cell phones and other items can take the worker’s attention off their duties and reduce their ability to hear on-coming hazards and must be prohibited on the job site.”
He says safe behavior goes beyond attention to their duties; workers must also be qualified, trained and clearly understand the hazards of their job and methods to reduce that risk.
5) Establish a contingency plan.
“Despite all of the efforts to reduce the probability of an incident, uncontrollable situations still arise and organizations should consider methods to reduce the probability of an incident occurring and reduce the severity of the incident should it still occur,” Carboneau said. For example, a blown tire can cause a motorist to lose control of his vehicle and enter the work zone. A medical situation could also cause a motorist to lose control, or he might still get distracted despite efforts to get his attention.
There are some common countermeasures, such as shadow vehicles, to reduce the chance a motorist will strike a worker and to reduce the severity of the incident. Another option is “buffer space,” Carboneau said. For example, “if they start hitting cones in the temporary traffic control taper, they will know they are in trouble and have time to stop before hitting a worker or other item in the work zone.”
“Something as simple as an air horn for a flagger is a last ditch effort to get a motorist’s attention before an incident occurs, or at least get the workers’ attention and hopefully reduce the chance and severity of an incident,” Carboneau said.
According to Carboneau, another key point is that site conditions can change throughout the day, depending on weather, traffic volume and duration of the work. He pointed out that there is a troubleshooting guide to help personnel in the decision-making process for flagger operations in the guidelines document. He said that although the document is meant for low volume roads, the strategies can apply to many situations.
“Contractors, public sector employees, utilities and other organizations that perform work on or near the road can use this document to improve the safety, efficiency and effectiveness of their temporary traffic control operations,” he said. “It goes beyond the minimums defined in the code, but also covers topics with which organizations are often seeking advice including use of flaggers and mobile operations.” <endmark>
Stopping Sight Distance
As a Function of Speed
20 mph 115 feet
25 mph 155 feet
30 mph 200 feet
35 mph 250 feet
40 mph 305 feet
45 mph 360 feet
50 mph 425 feet
55 mph 495 feet
60 mph 570 feet
65 mph 645 feet
*Posted speed, off-peak 85th-percentile speed prior to work starting, or the anticipated operating speed