Work zone safety is a particularly relevant topic given the large number of construction projects that are expected to arise as a result of funds allocated under the American Recovery and Reinvestment Act.
RSS831 Federal Highway Administration (FHWA) published a White Paper which was prepared by the 324 US Department of Transportation (USDOT) to inform public agencies about the use of ITS to manage construction work zones. This is a particularly relevant topic given the large number of construction projects that are expected to arise, in addition to already planned projects, as a result of funds allocated under the American Recovery and Reinvestment Act (ARRA). The paper contains information about examples of ITS applications and their benefits in work zones. A number of resources are also referenced.
"The White Paper provides information and does not reflect a USDOT policy position," says Tracy Scriba, Work Zone Technical Program Manager, FHWA Office of Operations.
"There have been various studies conducted by numerous different organisations but to date there has been no one document which synthesises things in such a way."
Over the last 15 years,, the number of people killed annually in accidents in work zones in the US has hovered around the 1,000 mark. In 2007, the last year for which statistics are held, there were 835 fatalities. That represents a 17 per cent fall over 2006, when 1,004 people lost their lives.
"Those figures include all fatalities - drivers, passengers and work zone operatives," says Scriba. "About 85 per cent of the fatalities are drivers and passengers so there is a major outreach effort intended to remind members of the public that they need to take extra care when passing through work zones."
On the operative side, not all fatalities are traffic-related. There are significant numbers of run-over and back-over accidents; the US Department of Labor and the US Department of Health and Human Services is currently undertaking research designed to prevent such accidents.
She feels that the US can learn much from Europe and elsewhere when it comes to the use of automated enforcement: "Use of this has increased in recent years but only a few states have the necessary legislation in place as yet. Maryland has passed legislation pertaining to work and school zones. Washington State has just completed studies on the use of automated enforcement and Illinois uses van-based mobile enforcement." Enforcement in work zones tends to emphasis spot speed checks and there is much that she believes that the US can learn from Europe, for example, where the use of average speed monitoring is already common. A barrier to this, she says is a lower level of acceptance of automated enforcement in the US by comparison with other places around the world.
Accurate traffic monitoring information has a role to play in, for example, adjustable lane closure times. Variable speed limits have also been used to a limited degree. The effect is akin to that of ramp metering and affects the amounts of traffic actually passing through work areas.
Dynamic merge systems are also gaining ground. Here, there are several schools of thought when it comes to the use of early or late merging. The choice tends to be dictated by traffic levels. Where there is very little traffic, the process tends to be self-regulating. Early merging might be favoured with middle-range traffic, although there is not yet universal agreement on this, while on heavily congested routes late merging allows the use of as much lane capacity as possible.
"We've tended not to go into such detail in the White Paper but there are case studies out there," says Scriba. "Michigan has done work on dynamic merging, for example, and there have been further evaluations elsewhere."
"There are opportunities for the use of both and there are generally three scenarios," Scriba continues. "Where there is no permanent, post-work monitoring solution planned there may be benefits to the temporary use of ITS. Where a permanent ITS solution is already in place it makes sense to use it if possible. Finally, where a permanent system is to be installed it might make sense to bring installation forward as much as possible to help with monitoring during the construction phase.
"Deployability is increasing all the time. Wireless solutions are increasingly common and there are now cone- and barrel-mounted solutions which allow the detection of errant vehicles or other types of data collection." A common lament of portable ITS systems manufacturers is that they tend to get a bad press because of their products' historical technological limitations. In reality, many of the newer-generation portable systems are very much more able and more than capable of interfacing with permanent solutions.
"We hope over time that portable systems can become more integrated and for example engage in information exchanges with nearby traffic management centres," Scriba says. "Standards are an ongoing consideration as far as work zones are concerned - as more and more permanent ITS solutions are deployed, this is an increasingly common problem. You have to remember that in major road construction or rehabilitation schemes 'temporary' can mean anything up to a couple of years - it doesn't necessarily mean 'short-term'."
Cellular is usually the medium of choice but satellite is used in some instances and there remain some line-of-sight solutions. Typically, the least-cost communications method that works for a given deployment is used which is why cellular tends to win out at present.
Scriba: "Although we're not yet at the stage of ITS use in work zones being ubiquitous, I think we're heading towards that. I don't think that there's a need for ITS use to be mandated, however. The requirement should be assessed on a case-by-case basis. There are a lot of site-specific issues - the actual work involved, its effect on traffic and the length of time it will go on for, for instance.
"The most successful deployments tend to look at ITS as one part of a whole solution. Regulation has moved on significantly in recent years with the publication of Subpart J of the Work Zone Safety & Mobility Rule. That expanded the scope of issues which agencies need to address. They have to assess impact levels and come up with management strategies; they have to flag 'Significant Projects' likely to have a high level of impact. It should be noted, though, that interpretation of a project's significance can vary from, say, rural Montana to downtown Chicago.
"Subpart J has also driven the need to develop transportation management plans. These are broader than the traffic control plans which preceded them as they also include public outreach and other, wider management strategies. The latter can be formal or informal depending on the project. Vehicle recovery and incident response strategies might be included and there might even be efforts towards demand management - working with local employers to spread the traffic load over a longer period of time."
All this stresses that ITS is but a part of the solution and Scriba says that it is important to avoid getting to a stage where technology is used indiscriminately. Although the White Paper does not include future cooperative infrastructure within the suggested work zone solutions, she does acknowledge the work going on within RITA on the IntelliDrive/Vehicle Infrastructure Integration programme.RSS
As the road-building season gets under way in the US, the Federal Highway Administration has just published a White Paper which deals with the use of ITS technology in work zones.
On 30 April 2009, the US"The White Paper provides information and does not reflect a USDOT policy position," says Tracy Scriba, Work Zone Technical Program Manager, FHWA Office of Operations.
"There have been various studies conducted by numerous different organisations but to date there has been no one document which synthesises things in such a way."
Over the last 15 years,, the number of people killed annually in accidents in work zones in the US has hovered around the 1,000 mark. In 2007, the last year for which statistics are held, there were 835 fatalities. That represents a 17 per cent fall over 2006, when 1,004 people lost their lives.
"Those figures include all fatalities - drivers, passengers and work zone operatives," says Scriba. "About 85 per cent of the fatalities are drivers and passengers so there is a major outreach effort intended to remind members of the public that they need to take extra care when passing through work zones."
On the operative side, not all fatalities are traffic-related. There are significant numbers of run-over and back-over accidents; the US Department of Labor and the US Department of Health and Human Services is currently undertaking research designed to prevent such accidents.
Intertwining strategies
Scriba stresses that safety and mobility applications are closely intertwined in any work zone management strategy. Accurate traveller information, in the first instance, can encourage drivers to avoid altogether areas where work is being carried out; one of the most common types of accident in work zones is where one vehicle rear-ends another and efforts to reduce, improve or smooth traffic flow can have a very positive effect on overall safety.She feels that the US can learn much from Europe and elsewhere when it comes to the use of automated enforcement: "Use of this has increased in recent years but only a few states have the necessary legislation in place as yet. Maryland has passed legislation pertaining to work and school zones. Washington State has just completed studies on the use of automated enforcement and Illinois uses van-based mobile enforcement." Enforcement in work zones tends to emphasis spot speed checks and there is much that she believes that the US can learn from Europe, for example, where the use of average speed monitoring is already common. A barrier to this, she says is a lower level of acceptance of automated enforcement in the US by comparison with other places around the world.
Accurate traffic monitoring information has a role to play in, for example, adjustable lane closure times. Variable speed limits have also been used to a limited degree. The effect is akin to that of ramp metering and affects the amounts of traffic actually passing through work areas.
Dynamic merge systems are also gaining ground. Here, there are several schools of thought when it comes to the use of early or late merging. The choice tends to be dictated by traffic levels. Where there is very little traffic, the process tends to be self-regulating. Early merging might be favoured with middle-range traffic, although there is not yet universal agreement on this, while on heavily congested routes late merging allows the use of as much lane capacity as possible.
"We've tended not to go into such detail in the White Paper but there are case studies out there," says Scriba. "Michigan has done work on dynamic merging, for example, and there have been further evaluations elsewhere."
Here today, gone tomorrow
Another issue which has been addressed is the use and interplay of permanent and temporary ITS systems."There are opportunities for the use of both and there are generally three scenarios," Scriba continues. "Where there is no permanent, post-work monitoring solution planned there may be benefits to the temporary use of ITS. Where a permanent ITS solution is already in place it makes sense to use it if possible. Finally, where a permanent system is to be installed it might make sense to bring installation forward as much as possible to help with monitoring during the construction phase.
"Deployability is increasing all the time. Wireless solutions are increasingly common and there are now cone- and barrel-mounted solutions which allow the detection of errant vehicles or other types of data collection." A common lament of portable ITS systems manufacturers is that they tend to get a bad press because of their products' historical technological limitations. In reality, many of the newer-generation portable systems are very much more able and more than capable of interfacing with permanent solutions.
"We hope over time that portable systems can become more integrated and for example engage in information exchanges with nearby traffic management centres," Scriba says. "Standards are an ongoing consideration as far as work zones are concerned - as more and more permanent ITS solutions are deployed, this is an increasingly common problem. You have to remember that in major road construction or rehabilitation schemes 'temporary' can mean anything up to a couple of years - it doesn't necessarily mean 'short-term'."
Critical mass
Work is also in progress on an ITS Work Zone Implementation Guide . This wide-ranging document will offer advice on implementing ITS in work zones, including the various communications strategies.Cellular is usually the medium of choice but satellite is used in some instances and there remain some line-of-sight solutions. Typically, the least-cost communications method that works for a given deployment is used which is why cellular tends to win out at present.
Scriba: "Although we're not yet at the stage of ITS use in work zones being ubiquitous, I think we're heading towards that. I don't think that there's a need for ITS use to be mandated, however. The requirement should be assessed on a case-by-case basis. There are a lot of site-specific issues - the actual work involved, its effect on traffic and the length of time it will go on for, for instance.
"The most successful deployments tend to look at ITS as one part of a whole solution. Regulation has moved on significantly in recent years with the publication of Subpart J of the Work Zone Safety & Mobility Rule. That expanded the scope of issues which agencies need to address. They have to assess impact levels and come up with management strategies; they have to flag 'Significant Projects' likely to have a high level of impact. It should be noted, though, that interpretation of a project's significance can vary from, say, rural Montana to downtown Chicago.
"Subpart J has also driven the need to develop transportation management plans. These are broader than the traffic control plans which preceded them as they also include public outreach and other, wider management strategies. The latter can be formal or informal depending on the project. Vehicle recovery and incident response strategies might be included and there might even be efforts towards demand management - working with local employers to spread the traffic load over a longer period of time."
All this stresses that ITS is but a part of the solution and Scriba says that it is important to avoid getting to a stage where technology is used indiscriminately. Although the White Paper does not include future cooperative infrastructure within the suggested work zone solutions, she does acknowledge the work going on within RITA on the IntelliDrive/Vehicle Infrastructure Integration programme.RSS
