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SECTION V--DESCRIPTION OF STRATEGIES
Cooper River bridge, additional funding was obtained for a lane for pedestrians and
future work activities so a lane would not have to be closed to perform work. Another
example is the provision for adequate space to allow positive barriers to be placed
between traffic and the work area. Physical barriers are discussed further under Strategy
19.1 C2.
Many DOTs have developed guidelines on how many lanes will be required to be
maintained during construction based on facility type or traffic volumes. Ohio DOT has
developed a "Permitted Lane Closure Map" for its network of freeways and
expressways. This map highlights the number of lanes that are present and the number
of these lanes that can be closed without exceeding a maximum allowable queue length.
North Carolina DOT uses established work zone capacity values for rural, suburban, and
urban facility types in assessing work zone operational requirements. This maintaining
information can be used to determine the effect that lane closures and other work zone
traffic control will have on capacity and delay. The information will help agency staff
who plan roadways to be able to address future work zone needs.
· Be aware of the long-term vision of roadway corridors. For example, if a four-lane facility is
being constructed, but the plan ultimately calls for six lanes, consideration should be
given to the future widening project, and the design of that work zone should be
considered during development of the four-lane project. The Ohio DOT is developing
guidelines on constructing a full-depth shoulder on roadways where work may be
planned within a certain time period.
Objective 19.1 B--Improve Work Zone Traffic Control Devices
Traffic control devices are used to communicate with drivers in advance of and within work
zones. It is critical that the devices are understandable and visible and provide useful
information. Since work zone conditions vary from typical roadway conditions, it is important
to inform the driver of the desired actions and the correct path through the work zone. In
addition to use of conventional signing and media outlets, route decision making can be
enhanced using ITS to inform drivers of delays and alternative routes. Traffic signs, pavement
markings, and work vehicles should be well maintained and visible in both daytime and
nighttime conditions. Visibility of workers is also a key issue in work zone safety.
19.1 B1--Implement ITS Strategies to Improve Safety (E)
General Description
ITS tools--such as traffic monitoring, advanced travel time, delay, and route information--
can improve safety and mobility for travelers in work zones and on the approaches to work
zones. This improvement is accomplished through communication with travelers and
between elements of the system, which includes agency personnel. The information
gathered from the roadway environment is transmitted to agency personnel and road users
to allow them to make better safety and mobility decisions.
Using ITS in work zones can improve traffic safety by alerting drivers to the presence of
the work zone and real-time conditions in the work zone. This advanced notice can warn
drivers that they may need to reduce their speed or stop. Because travelers have advanced
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SECTION V--DESCRIPTION OF STRATEGIES
information regarding delays in the work zone, as well as information on alternative routes
or detours, the drivers can make route choices in advance of the work zone. Thus, mobility
is improved. The length of the backup, as well as an estimated travel time, can be
communicated to travelers. ITS can be used to convey work zone speed limit information,
as well as messages on increased enforcement or higher fines in the work zone. With the
data collected by a system, agency personnel can better respond to incidents and relay
messages to the public as needed. Detection of accidents can allow faster action by
appropriate emergency response personnel, and this faster action can in turn minimize the
impacts of accidents on traffic flow, including potential for secondary crashes. Messages
conveying the location of an accident can be relayed to travelers quickly.
ITS can be used for functions that typically have been performed manually. It is possible to
incur lower project costs by using ITS to automate transfer of information to agency
personnel and travelers. Remote sensors collect data on traffic volume, speed, and/or
queues and relay this information to a central control center. The data are processed and
communicated to transportation agency staff and travelers. Agency staff are able to override
messages relayed to the public if adjustments are needed. Portable system elements may be
appropriate for rural or short-term installations.
New ITS technologies are developing at a fast pace. Some of the more common technologies
applied to work zones are shown in Exhibit V-9.
Several systems have a specific focus on improving safety in work zones and are described in
further detail in the FHWA's Intelligent Transportation Systems in Work Zones (FHWA, 2002):
· Dynamic message signs advise drivers of slower downstream speeds and travel times.
This technology has been effective in reducing speeds in congested flow conditions, but
not during uncongested flow. The technology can offer the road users information that
may minimize frustration and associated aggressive driving.
· A highway advisory radio broadcasts advisory messages to drivers. A sign (dynamic
or fixed message) informs drivers of the correct radio station, and messages regarding
traffic delays, detours, road closures, and other travel conditions in the area can be
broadcast.
EXHIBIT V-9
Example System Components for Use in Work Zones
ITS Components for Data Collection and Processing: Central controller/sensors
Closed circuit television cameras
Remote sensors
ITS Components for Communication with Travelers: Dynamic/changeable message signs (portable or fixed)
Internet
Highway advisory radio
Telephone information line
In-vehicle navigation systems
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· A citizens band radio channel broadcasts advisory messages. A survey showed that a
majority of truckers, whom the system targets, hear the message and think it is a
worthwhile method of communicating.
· Portable signs define the length of a dynamic no-passing zone based on the length of a
traffic queue. As a queue lengthens, the next upstream "DO NOT PASS" sign lights up.
This is a regulatory (and therefore enforceable) sign.
· A portable trailer measures vehicle speeds and displays the speeds for the driver. In a
study based on a limited amount of data, this system was shown to reduce speeds and
variations in speeds in the work zones where deployed and, on occasion, downstream
of the work zone (Maze et al., 2000).
· Variable work zone speed limits reduce speed limits when workers are present. This
strategy is experimental; therefore, the effectiveness of it in reducing crashes is
unknown. A work zone speed limit may vary depending on whether workers are
present or on other factors; therefore, the speed limit may vary in long work zones.
Legislative authority may be needed for an agency to implement this strategy. Appendix
2 discusses variable speed limits in more detail.
· Speed warning systems communicate average downstream speeds to drivers on
variable message signs. This technology warns drivers that they may soon need to slow
down or stop.
· Web cameras provide real-time visual traffic condition information. Video cameras used
to monitor traffic can provide images to be broadcast on a website or on television
stations. Traffic reporters can use these images, and drivers can check the website for an
update on traffic conditions before beginning their travel.
Illinois DOT has instituted a program of speed-monitoring cameras in work zones similar
to other applications (e.g., red-light running cameras).
ITS strategies are generally more applicable to larger projects on high-volume facilities over
long construction periods. Such projects are in one sense beyond the focus of the SHSP.
However, in the context of an agency changing its practices and methods for all projects
moving forward, the strategies are appropriate.
EXHIBIT V-10
Strategy Attributes for Implementing ITS Strategies to Improve Safety (E)
Attribute Description
Technical Attributes
Target ITS strategies target crashes related to congestion caused by work zones--
speeding, aggressive driving, and unexpected conditions--as well as crashes that
may be related to driver confusion or lack of information, such as last-minute
correction of navigation errors (i.e., swerving). Related crash types include rear-end
crashes, side swipes, or head-on crashes. ITS strategies warn drivers of the
potential need to decelerate or stop and provide drivers with alternative route
information.
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SECTION V--DESCRIPTION OF STRATEGIES
EXHIBIT V-10 (Continued)
Strategy Attributes for Implementing ITS Strategies to Improve Safety (E)
Attribute Description
The types of work zones that may be appropriate for ITS applications include:
· High-volume roadways where delays may be common or where detours will be used,
· Work zones that may involve changes in travel patterns, and
· Work zones where high speeds are expected or have been experienced.
Long-term projects are more ideal situations for ITS use, since the system costs will
be more easily justified. Any situation that necessitates communication with drivers
while they are in or approaching the work zone may be appropriate for ITS
applications. ITS systems are more likely to be used to improve mobility in urban work
zones and to improve safety in rural work zones.
Expected Effectiveness The complex and individual nature of work zones creates difficulty in evaluating the
effectiveness of specific technologies and applying the estimated safety improvements
to other projects. Although no studies conclusively prove that ITS technologies reduce
work-zone-related crashes, anecdotal information from a variety of work zones on
which ITS strategies were used suggests that the crash rates were lower than
expected. A reduction in volume through a work zone should reduce the crash
experience of that work zone, and use of ITS to provide information on downstream
traffic conditions and alternative routes can help divert traffic from the work zone to
other routes, thereby lowering exposure and reducing crashes.
The FHWA report Intelligent Transportation Systems in Work Zones: A Cross
Cutting Study (2002) states that the New Mexico State Highway and Transportation
Department reported a smaller increase in crashes (7 percent) than expected
during the rebuilding of the I-40 and I-25 interchange, as compared with the crash
experience before the construction project began. Secondary crashes were
reduced as well, and this is thought to be due to a reduction in the time to clear
incidents. A PI&E campaign, increased enforcement, and ITS were likely the main
contributors to an initial 32-percent decrease in crashes during the first 3 months of
construction. Other projects reported in the FHWA study experienced low numbers
of crashes as well.
Wisconsin DOT evaluated the accuracy of travel time messages for a work zone
displayed on variable message signs. Traffic flow data were collected using roadside
sensors, and this information was used to estimate travel times. Variable message
signs were placed in locations where drivers had the opportunity to exit the freeway
under construction (or not to enter it) if they chose. A comparison of these calculated
times with actual travel time data showed that the travel times displayed on the
variable message signs were relatively accurate. The difference between actual and
predicted travel times was 2 to 3 minutes, on average. Fewer injury crashes were
experienced on this section of the freeway after the travel time messages were put
into use than in the control section of the roadway (a similar work zone in the opposite
direction of travel). (These data were collected for approximately 2 months and the
results should be used with caution.) (Notbohm et al., 2001).
It is also expected that drivers in congested conditions will experience less frustration
and be less inclined to take aggressive action if informed about the length of the
congestion, in terms of both time and distance.
Emergency response times and, potentially, crash survivability may also be
improved when ITS strategies are used to detect incidents and determine the
appropriate types of responders.
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SECTION V--DESCRIPTION OF STRATEGIES
EXHIBIT V-10 (Continued)
Strategy Attributes for Implementing ITS Strategies to Improve Safety (E)
Attribute Description
Keys to Success Keys to success are related to planning and administration of the system to be
implemented and technical details related to information provided to travelers and
agency personnel.
As a system is being developed, the transportation agency implementing the system
should coordinate with other stakeholders, such as emergency responders. One issue
to consider is how information will be shared with police and emergency medical
providers so that resources are used appropriately and efficiently when incidents
occur. The public is another key stakeholder to consider during planning, and a PI&E
campaign should inform the public of the technologies that will be used and their
benefits, as well as the information that will be provided by the ITS. Throughout the
project, accurate information is needed (FHWA, 2002).
A plan for handling problems with the system components will need to be developed
with consideration for placing staff on-call during nonbusiness hours to handle
problems. The reliability of the communications system should be confirmed before
implementation. The schedule will need to include some time for startup of the
system, which includes activities such as calibration of traffic detectors and accounting
for traffic scenarios that may not have been initially programmed into the system.
Periodic--possibly daily--checks on system performance will need to be performed
(FHWA, 2002).
It is important that variable message signs information be provided to travelers far
enough in advance of the back of the queue for them to be able to take alternative
routes. The advance warning signs should also be appropriately spaced so that
drivers do not encounter a queue before they reach the sign warning them of the
queue.
A portable system remotely operated by cell phone may be more appropriate for a
rural work zone, where a traffic command center would not be available or needed.
Portable systems are applicable in situations where a system is needed for a relatively
short time (such as for a planned event). These systems can work with sensors and
without the need for an operator.
Providing accurate and up-to-date information to drivers is important as well. Should
drivers repeatedly find information to be old or inaccurate, they will learn to disregard
the information.
Adequate planning is needed for the system, especially larger complex ones, since
the system will need to be customized for the specific situation (such as setting up
web cameras). Contractors will often lease the system from a vendor, so time and
planning are needed to allow for this. Having a separate contract for the ITS portion of
the project can allow the planning for and implementation of the system to proceed
separately from the construction contract to ensure that the system is in place before
construction begins.
Potential Difficulties Costs associated with the purchase or lease of ITS components can be significant.
Agencies should make efforts to reduce difficulties with system components during
startup and initial periods of system use. Comprehensive testing of the system should
be performed.
Lack of cell phone coverage may limit the applicability of systems intended for use in
rural areas in which sign messages are controlled by cell phones.
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SECTION V--DESCRIPTION OF STRATEGIES
EXHIBIT V-10 (Continued)
Strategy Attributes for Implementing ITS Strategies to Improve Safety (E)
Attribute Description
Typical weather conditions that may be expected during the duration of the work
should be considered when choosing systems that detect traffic queues or incidents.
For example, video detection of incidents may be hampered during periods of
heavy fog.
Appropriate Measures A key process measure is the number of projects on which ITS technology is used.
and Data The types of systems and quantities of each, as well as system malfunctions, should
be used to measure the implementation process.
Key safety effectiveness measures include crash frequency and severity, by type of
crash. It is important to consider crashes related to the presence of the work zone,
as well as to identify crashes related to traffic diversion to an alternative route.
These might include congestion-related crashes on the detour routes, such as
rear-end crashes.
Crash frequency and severity data are needed to evaluate the construction operation
for safety effectiveness. Traffic volume data are needed to represent exposure,
including changes in volumes on alternative routes during the construction. Changes
in traffic volume in the work zone can be used to determine the exposure of traffic to
the work zone and the exposure of workers to traffic. Delay data are needed to
determine the operational impacts of the project on traffic flow.
Citations in the work zone may be an appropriate surrogate measure of safety.
Changes in the number of citations for speed violations, from before construction to
during construction, can be used to evaluate possible changes in the level of safety.
Associated Needs The deployment of specific ITS equipment may require skills not present among the
personnel of the highway agency. Therefore, private contractors may be needed to
implement and/or maintain the system.
Organizational and Institutional Attributes
Organizational, Coordination with other agencies--such as emergency response providers, local
Institutional and jurisdictions, and land users adjacent to the work zone that may be affected by the
Policy Issues project--should be a part of the planning process, and this coordination should
continue throughout the project. Some education may be required so that personnel
from these other agencies are aware of how the ITS work zone system works.
Stakeholders with incident management responsibilities should have a significant role
in determining how the system is used for and affects emergency response.
New policies and procedures may be required to guide the application of ITS
technologies in the jurisdiction.
Issues Affecting Agencies should not need to spend significant effort to begin using ITS on
Implementation Time construction projects. It may be desirable to establish a procedure for comparing the
costs of various systems with the benefits. Much of the equipment needed may not be
available and would need to be ordered in advance of a project. This would add to the
initial implementation time. If an ITS contractor/consultant is required for a
construction project, it may require additional time to finalize a contract.
It may be desirable to install already-planned permanent or long-term ITS before a
construction project begins. In such a case, a separate system would not be needed
during construction. This would also be a good time to update an existing system.
Installing the ITS technology before the construction begins can either increase
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SECTION V--DESCRIPTION OF STRATEGIES
EXHIBIT V-10 (Continued)
Strategy Attributes for Implementing ITS Strategies to Improve Safety (E)
Attribute Description
implementation time (if the installation was scheduled to occur some time after the
construction project) or decrease implementation time (if the system is nearly ready
to be installed and does not need to be added to the construction contract).
PI&E campaigns for the construction project should include an element to make
travelers aware of the ITS technologies being used. In some cases, the ITS
technologies will need to be fully operational before construction can begin, and this
will need to be planned into the implementation time for individual projects.
Costs Involved Establishing procedures for including ITS in work zones will be of minimal cost.
ITS components can be purchased or leased, and the cost will depend on the
complexity of the system and the individual technologies included in the system. The
FHWA (2002) reports that ITS work zone systems cost less than 1 to 10 percent of the
total project cost for the construction projects highlighted in the document.
An analysis of over 100 planned ITS projects in Nebraska led to development of
benefit/cost (B/C) ratios for the system deployments. The systems studied were
planned for permanent use, rather than work zones. The projects were expected to
have an average B/C ratio of 1.5. Types of ITS programs with the highest expected
B/C ratios were tourism and traveler information systems, commercial vehicle
operation systems, and traveler safety and security systems (McCoy et al., 1998).
Training and Other Agency design staff will need to be trained on what technologies are available and in
Personnel Needs what situations they are applicable and appropriate. If support of the ITS components
is not included in the vendor's contract, agency personnel will most likely need to be
trained by the vendor so that they can operate and maintain the system.
Legislative Needs None identified.
Other Key Attributes
Compatibility of Most technologies that fall into the broad category of ITS are compatible with other
Different Strategies strategies discussed in this guide and may enhance the effectiveness of other strategies.
Other Key Attributes In addition to lessening the impact of the work zone on road users, cooperation with
to a Particular Strategy stakeholders such as the public and emergency response providers can improve
relations with these groups and improve the confidence that these groups have in
agency personnel and programs. Examples of these benefits are documented by
FHWA (2002).
Agencies should consult legal personnel to determine whether certain data, such as
camera images, should be archived.
Key References
Carlson, P.J., M. Fontaine, H.G. Hawkins, K. Murphy, and D. Brown, "Evaluation of Speed
Trailers at High-Speed Temporary Work Zones." Paper No. 00-1475. Transportation
Research Board, Compendium of Papers CD-ROM, Washington, D.C. 2000.
Colorado DOT, TDM Toolkit. 2002. http://www.dot.state.co.us/CommuterChoice/
TDM/TDM.htm.
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Federal Highway Administration, Intelligent Transportation Systems in Work Zones: A Cross
Cutting Study. Report No. FHWA-OP-02-025. Washington, D.C. 2002.
http://www.itsdocs.fhwa.dot.gov/JPODOCS/REPTS_TE/13600.html.
Federal Highway Administration, ITS Operations Resource Guide. 2003.
http://www.itsdocs.fhwa.dot.gov//JPODOCS/catalog/frame_sec6_zones.htm.
Federal Highway Administration, Mitigating Traffic Congestion--The Role of Demand-Side
Strategies. Washington, D.C. 2004. http://ops.fhwa.dot.gov/publications/mitig_traf_cong/
index.htm.
Fontaine, M.D., "Guidelines for the Application of Portable Work Zone Intelligent
Transportation Systems." Paper No. 03-2700. Transportation Research Board,
Compendium of Papers CD-ROM, Washington, D.C. 2003.
King, T. W., C.C. Sun, and M.R. Virkler, "Evaluation of a Freeway Work Zone Speed
Advisory System Using Multiple Measures." Paper No. 04-2401. Transportation Research
Board, Compendium of Papers CD-ROM, Washington, D.C. 2004.
McCoy, P.T., S.L. Gaber, J.A. Gaber, and W.D. Tobin, Nebraska Intelligent Transportation
Systems Statewide Strategic Plan. Nebraska Department of Roads. Lincoln, Nebraska.
FHWA-NE-99-P511. 1998.
Maze, T., A. Kamyab, and S. Schrock, "Evaluation of Work Zone Speed Reduction
Measures." Iowa State University Center for Transportation Research and Education. Ames,
Iowa. April 2000.
Notbohm, T. , A. Drakopoulos, and A. Horowitz, Smart Work Zone Deployment Initiative
Summer 2001 Travel Time Prediction System. 2001. http://www.eng.mu.edu/~drakopoa/
web_documents/TIPS/Tipswisconsin.pdf.
Information on Current Knowledge Regarding Agencies or Organizations
That Are Implementing This Strategy
The FHWA report Intelligent Transportation Systems in Work Zones: A Cross Cutting Study
(2002) describes construction projects that used ITS in the work zones to successfully
provide real-time travel information to travelers, reduce delay, and reduce time to
clear incidents.
19.1 B2--Improve Visibility of Work Zone Traffic Control Devices (T)
General Description
Visibility of traffic control devices can be limited by poor retroreflectivity, obstructions, sight
distance, weather conditions, wear, and other factors. Lack of visibility of traffic control
devices can contribute to crashes in work zones. Providing adequate visibility of traffic
control devices aids in drivers' advance perception of the travel path through the work zone,
especially at night. Poor visibility of signs and markings may result in drivers
unintentionally violating the intended message of a regulatory or directional sign. Also,
drivers' attention may be focused on other objects in the work zone or work activities in
an adjacent lane rather than on signing. The visibility of signs, markings (including raised
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SECTION V--DESCRIPTION OF STRATEGIES
pavement markers), and channelizing devices may also be affected by degradation of the
reflectivity of the device, the interference of physical objects (e.g., equipment, other vehicles,
dirt, or road sludge), atmospheric conditions (e.g., fog), and darkness. Maintenance of traffic
control devices is important to the visibility of the devices. If visibility of traffic control
devices is considered to be a potential factor in crashes that have occurred, field reviews may
be regularly performed, especially at night, to determine if part of a device's message is
obscured, obliterated, or blocked, as well as to check the retroreflectivity of the device.
In addition to potentially restricting driver sight lines, signs not associated with the driving
task and a large numbers of appurtenances in the vicinity of a work zone can impose a high
workload on drivers. The need for numerous traffic control devices in work zones,
combined with the presence of existing signs and devices, plus background clutter created
by advertising signs, street lighting, and so forth often make it difficult to select and locate
temporary traffic control devices to ensure adequate visibility in work zones. It is therefore
essential to adhere to the Manual on Uniform Traffic Control Devices (MUTCD) guidance to
ensure that all work zone traffic control devices are properly selected, designed, and located
to provide adequate visibility and driver comprehension. An analysis of driver information
workload may be needed to identify potential problem areas.
State agencies are encouraged to adopt their own visibility standards for work zone traffic
control devices. The standards would apply not only to signs and pavement markings, but
also to barricades and channelizing devices such as cones and barrels. The American Traffic
Safety Services Association (ATSSA) has recommended guidelines for the condition of
temporary traffic control devices, and many states follow these or equivalent standards
(available online at http://www.atssa.com/resources/statepolicies.asp). In addition, FHWA
is developing standards for retroreflectivity.
Frequent inspections are needed to ensure that an agency's visibility standards are met in
work zones. Agencies are encouraged to require that a person certified in development and
implementation of traffic control plans oversee the traffic control in work zones. It is
important to follow up with contractors to make sure traffic control supervisors are being
used on projects where this is recommended or required. It may be desirable to have more
than one supervisor, possibly at least one on the contractor's staff and one from the highway
agency staff, to be able to monitor more of the time when the work zone is active, especially
when work is occurring for long periods (such as 24-hour operations). The recent FHWA
rule on work zone safety and mobility requires contractors and state highway agencies to
designate a trained person to be responsible for "implementing a transportation
management plan and other safety and mobility aspects of the project." Beginning in
January of 2005, South Carolina DOT has required all construction work bids to have a
certified work zone traffic control supervisor. Certification is obtained during a 3-day
training course.
Nighttime visibility is an important consideration when determining appropriate traffic
control devices to use in a work zone. Drivers and pedestrians at nighttime tend to be less
alert and are more often driving under the influence of alcohol or drugs than during
daytime. "A significant problem with night work, then, is that drivers need more visibility
at a time when conditions reduce visibility" (Bryden and Mace, 2002, NCHRP Report 476).
The clues that drivers are able to pick up from the roadway environment that help them
steer their vehicles along the appropriate path are not as evident at night, and reliance on
signs and markings increases. Increased conspicuity of signs and markings provides more
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information to drivers at a greater distance, and this is especially important at night. NCHRP
Report 476 and NCHRP Report 498 should be consulted for additional information about
nighttime visibility of traffic control devices.
Older drivers are particularly susceptible to involvement in work zone crashes due to their
often increased difficulty in responding to situations that violate driver expectancy and due
to their significantly decreased visual acuity, especially in periods of reduced visibility such
as night and poor weather. Decreased visual and other functional capabilities compound the
issues related to the unique nature of every work zone. The older driver guide in this
NCHRP Report 500 series (Volume 9) should be consulted for additional information on
improving work zones to accommodate older drivers. In addition, the FHWA Older Driver
Highway Design Handbook (1998, available at http://www.fhwa.dot.gov/tfhrc/safety/
pubs/older/home/index.htm) should be consulted to ensure that improvements to visibility
of traffic control devices will be appropriate for older drivers. Also, see Appendix 3 for a
brief summary of some research on traffic sign visibility, performed by the United States
Sign Council, with emphasis on the mounting height.
Methods for improving visibility of signs, pavement markings, and channelizing
devices include:
· Implement visibility (i.e., retroreflectivity) standards (or ATSSA condition guidelines or
the equivalent).
· Upgrade sign sheeting materials. Use of highly reflective or fluorescent sign sheeting can
provide improved visibility for work zone signs. Use fluorescent orange sign sheeting
where low-light conditions are expected during the work zone operation. Fluorescent
sheeting does not provide much additional value during bright daylight or nighttime
conditions and therefore may not be appropriate for work zones that are set up and
taken down daily.
· Provide larger signs on high-speed roadways where clutter is not a concern. Where sign
density is higher (such as on urban roadways), temporary signs need to fit in with
existing traffic control and cannot block other devices. Larger letter height and stroke
width can help increase visibility as well. Crash experience on a roadway can be used to
determine if larger signs may be appropriate for a work zone on that roadway.
· Provide redundancy in signs on high-speed rural roadways and for critical signs.
· Increase sign spacing on high-speed roadways to allow more time for drivers to process
the information on the signs and to prepare for the required maneuver.
· Provide artificial lighting on work zone signs.
· Provide flags and/or warning lights on work zone signs.
· Increase the size of channelizing devices.
· Decrease the spacing of channelizing devices.
· Avoid using Type III barricades near intersections and ramps, except for full road
closures (where Type III barricades are required). Other channelizing devices, such as
Type II barricades, drums, and vertical panels, especially if closely spaced, can provide
equivalent path guidance to drivers without blocking sight lines.
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EXHIBIT V-11
Positive Guidance: Excellent Temporary Marking and Channelizing Devices
· Install highly reflective temporary pavement markings to delineate intended travel
paths; a material with high visibility in both dry and wet conditions is ideal. A wet
reflective tape product is available that provides increased visibility in wet conditions.
Refer to the section entitled "Information on Current Knowledge Regarding Agencies
or Organizations That Are Implementing This Strategy" for one agency's experience
with this product.
· Ensure adequate visibility of signs and markings on detour routes. Improvements need
to be made as appropriate to accommodate increased volumes of traffic anticipated due
to diversions from the work zone.
· Improve the display of sign messages through changes in colors, contrast, pictorial or
text messages, font style, letter height, and stroke width. Reduction of glare from signs
and adjusting mounting height and location relative to travel way as appropriate can
improve visibility of signs.
Another aspect of visibility of traffic control devices relates to the obliteration of temporary
markings when the control plan changes in a work zone. Construction and maintenance may
be done in stages so that vehicles are directed over different paths at various stages of work.
When the paths change, the temporary and permanent markings that are present for a
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· Flag trees (T): Flag trees are high-level devices that provide additional warning that
flaggers are present. They may be less effective in urban or congested areas than in rural
areas due to visual clutter of the background. However, flag trees in urban areas may be
more visible than flaggers since they can be taller than flaggers and more easily seen
over taller vehicles. Flag trees may not be feasible for mobile or short-term work where
frequent moving of the trees is needed.
· Additional advance warning of flagger presence (E): Centerline cones may be placed
upstream of a flagger station to alert drivers to the presence of a flagger in the roadway.
This may not be ideal on narrow roadways or where drivers may be confused by the
cones and may drive on the left side of them (NYSDOT, 2005).
· Flashing stop/slow paddles (E): Another method for increasing
flagger visibility is to use stop/slow paddles with flashing lights. The
paddles have high-intensity lights on the "stop" side that flaggers
can activate when needed (i.e., when it appears that a driver has
not noticed the flagger and sign). Alerting a driver to the presence
of a flagger and sign should increase the chances of the driver
stopping or slowing and avoiding crashes. Information on states'
experiences with flashing paddles can be found on the FHWA
website at http://www.fhwa.dot.gov/winter/roadsvr/
byproduct.htm (listed under "flashing stop/slow paddle").
· High-visibility apparel (T): Flaggers generally stand facing traffic, but this is not always
true for workers performing other tasks. Therefore, they need to be visible from all
directions in any position (stooping, facing away from traffic, and so on). This means
that since it is unpredictable which part of the body will need to be visible to traffic and
other construction personnel, there is a great need for a worker's entire body to be
visible. At night, flaggers are often illuminated by headlights and therefore can be made
more visible with retroreflective clothing, but other workers not directly exposed to
traffic cannot rely on retroreflectivity. Light-colored clothing, in addition to
retroreflective vests and hard hats, should be worn to make workers visible under both
headlights and more diffused work lighting (Bryden and Mace, 2002). Encircling hard
hats with high-visibility tape will help improve visibility of workers as they are
positioned sideways with respect to oncoming traffic and as they therefore have a
smaller cross section of high-visibility apparel facing traffic.
The American National Standard for High-Visibility Safety Apparel (ANSI/ISEA 107-
2004) established three levels, or conspicuity classes, of high-visibility apparel for
workers. This is a consensus standard developed by ISEA through ANSI and is not
currently included in the latest version of the MUTCD. The level of apparel a worker
needs to wear (per these standards) is dependent upon the type of work, vehicular
traffic, hazards, and other activities in the work zone. Class 3 apparel is the most visible
in a wide range of weather and lighting conditions and is appropriate for use where
traffic speeds are 50 mph or greater. Additional discussion of the classes of apparel is
available on the Center for Disease Control and Prevention website at
http://www.cdc.gov/elcosh/docs/d0600/d000627/d000627.html.
In order for workers to be visible against the background of construction equipment and
vehicles, clothing with a striped pattern, rather than a solid color, may provide additional
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SECTION V--DESCRIPTION OF STRATEGIES
EXHIBIT V-14
Highly Visible Flagger at Night--Apparel, Temporary Lighting
visibility (Bryden and Mace, 2002). Use of yellow-green colors in worker apparel may help
improve worker visibility against a background of orange construction equipment, signs,
and barricades. Fluorescent apparel can enhance visibility during dawn and dusk. Varying
apparel colors by season to ensure that workers stand out against the foliage background is
suggested by Pratt et al. (2001). For example, South Carolina DOT does not use yellow-green
apparel because workers wearing that color do not stand out well against the pine forest
background commonly found in the state.
Visibility of Work Zone Vehicles
Improvements to visibility of work zone vehicles include:
· Use more visible paint colors, conspicuity tape, or retroreflective materials or backup
alarms to increase road user and worker awareness of work zone vehicles (T):
Increased visibility of work vehicles will provide road users with more warning that
vehicles either are present or may be entering the traffic lanes.
· Use backup alarms or video cameras to increase worker awareness of work zone
vehicles and driver awareness of other workers (T): Backup alarms are used to alert
people in the vicinity of a vehicle that it is backing up. These alarms are sometimes
objectionable to residents in the vicinity of a work zone, and an alternative can be an
observer who signals to a vehicle operator when it is safe to proceed in reverse. Video
cameras can be used to provide the view behind the vehicle as the operator is backing up.
· Use advance warning vehicles to alert drivers to the presence of a work zone (T):
The AASHTO 2002 Roadside Design Guide discusses appropriate use of advance
warning vehicles (shadow and barrier vehicles) and truck-mounted attenuators.
Advance warning vehicles should be equipped with warning lights, such as rotating
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SECTION V--DESCRIPTION OF STRATEGIES
beacons or strobe lights. Strobe lights, however, can be fatiguing to workers in
nighttime conditions (in addition, strobe lights can trigger seizures in some people
with epilepsy). Arrow panels are recommended for use on shadow and barrier
vehicles as an effective means of warning drivers that a lane is closed. These panels
should be mounted as high as possible on the vehicles and should be as large as
possible to provide the most visibility. The arrow panels should be dimmed at
night to a maximum of 50 percent of full intensity to avoid glare problems for
approaching drivers.
· Use combinations of warning light colors (T): A combination of colors for warning
lights may convey a message of greater hazard warning to drivers. A study of several
freeway sites in Texas showed a 5- to 6-mph decrease in speed of vehicles approaching
maintenance vehicles with a combination of yellow and blue warning lights at two of
five sites. This color combination resulted in an increase in brake usage as well and an
even greater increase when red-yellow-blue warning lights were used. Different color
lights did not have a significant impact on the tendency of drivers to change lanes as
they approached the maintenance vehicle with the warning light. The presence of a law
enforcement vehicle was shown to influence drivers to brake more frequently than a
TxDOT courtesy patrol vehicle (Ullman, 2000). Warning lights in colors other than
yellow should be used only when a specific need exists for these lights and only when
permitted by the jurisdiction in which the work zone is located (Bryden, 2003).
Nighttime Visibility
Nighttime visibility of workers and vehicles is an important consideration when
determining whether to perform work during the day or night. Visibility is reduced at night,
and there are also concerns related to driver expectancy and the potential for fatigued or
otherwise impaired drivers.
EXHIBIT V-15
Visible Work Vehicle at Night--Arrow Board, Reflective Signs
and Markings, Warning Lights
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Retroreflective material on apparel and vehicles will improve their visibility. Strobe lights
are highly visible and less costly than incandescent flashing/rotating lights for vehicles, but
are believed to be more difficult for drivers to determine both the distance to them and the
rate at which the distance is closing. Light bars provide good visibility but may be difficult
to be visible from 360° around a large vehicle. Additional guidance on use of warning lights
at night is provided by Bryden (2003).
For nighttime construction, adequate lighting is necessary to allow workers to complete
their tasks efficiently as well as increase the visibility of workers and vehicles. Care should
be taken to minimize the glare experienced by both workers and drivers. Consideration of
glare-free light balloons is suggested by Pratt et al. (2001).
EXHIBIT V-16
Strategy Attributes for Improving Visibility of Work Zone Personnel and Vehicles (Varies)
Attribute Description
Technical Attributes
Target The principal targets are worker and vehicle visibility, which affect crashes that occur
when drivers either are not aware of the presence of workers or vehicles or fail to see
them due to distractions or reduced visibility. Such crashes would involve either a
vehicle striking a worker (whether a flagger or other worker directly exposed to traffic)
construction vehicle or a vehicle intruding on the work space. Also, lack of worker or
equipment visibility could contribute to a collision between vehicles traveling through
the work zone should drivers make erratic maneuvers to avoid a worker or work vehicle
that was not seen. These crash types would include rear-end crashes and possibly
side-swipe, angle, and head-on crashes, depending on work zone configuration.
Work zones of all types would be appropriate sites for improving visibility of workers
and vehicles.
Expected Effectiveness It can be expected that improvements in visibility will have a positive effect on crash
experience. Methods for improving visibility of work zone personnel and vehicles have
been evaluated, and treatments such as high-visibility apparel and warning lights have
been shown to be effective in improving visibility. While it is difficult to quantify the
effectiveness in terms of crash reduction in work zones, it is known that a substantial
number of work zone crashes involve vehicles traveling through the work zone that
strike a worker or work vehicle/equipment. It is reasonable to expect improved
visibility to reduce the number of such crashes.
Keys to Success One key to success is to have well-developed agency guidelines for the use of
apparel and other methods to improve worker and vehicle visibility.
Another key to the success of visibility improvements is frequent inspection of worker
clothing, vehicle warning lights, and other enhancements to ensure that the devices
are clean, functioning, well maintained, and providing an appropriate level of visibility.
Potential Difficulties If high-visibility materials are not maintained properly, the expected benefits may be lost.
It is important to ensure that any lighting that improves visibility of workers and
equipment does not create glare for drivers passing through the work zone, workers,
or drivers of construction vehicles.
Appropriate Measures The existence--or development, if necessary--of a clear policy on worker and work
and Data vehicle visibility is a primary process measure. Another key process measure is the
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SECTION V--DESCRIPTION OF STRATEGIES
EXHIBIT V-16 (Continued)
Strategy Attributes for Improving Visibility of Work Zone Personnel and Vehicles (Varies)
Attribute Description
project on which worker and vehicle visibility is improved. The types of improvements
and the number of applications of each should be used to measure the
implementation process as well.
Key safety effectiveness measures include crash frequency and severity, by type of
crash. It is important to consider crashes related to visibility of workers and work
vehicles in the work zone.
Crash frequency and severity data are needed to evaluate the construction operation
for safety effectiveness. Traffic volume data are needed to represent exposure.
Associated Needs None identified.
Organizational and Institutional Attributes
Organizational, Highway agencies should review and revise, as appropriate, policies regarding worker
Institutional and and vehicle visibility to facilitate appropriate action being taken on routine projects.
Policy Issues Good quality control/quality assurance procedures and practices at the project level
are also necessary.
Nearly any highway agency can implement this strategy, which is applicable to work
zones on any facility type in rural, urban, and suburban areas where work occurs
either during the day or at night.
Complete cooperation of contractors and all field staff is important. Contract provisions
should clearly specify the visibility requirements for both personnel and equipment
used on the project.
Issues Affecting Implementation time will be relatively short for procedures to improve visibility, such as
Implementation Time installing markings or lights on vehicles or lighting for the work area, and for workers
to begin wearing high-visibility apparel.
Costs Involved Costs will be low for most procedures to improve visibility and awareness of the work
zone personnel and vehicles. Ongoing maintenance costs should be included in cost
considerations. Cost elements will include apparel purchases, painting of vehicles,
and installation of appropriate lighting fixtures.
Training and Other Visibility of work zone personnel and vehicles should be addressed in highway agency
Personnel Needs training concerning work zone safety. Contractors may also need to undergo training
that includes discussion of ways to improve worker and vehicle visibility.
Legislative Needs Use of different combinations of colored warning lights (such as yellow and blue) may
require enabling legislation.
Other Key Attributes
Compatibility of Actions taken to improve visibility of work zone personnel and workers are compatible
Different Strategies with other strategies to improve work zone safety.
Key References
American Association of State Highway and Transportation Officials, Roadside Design Guide.
3rd Edition. Washington, D.C. 2002.
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SECTION V--DESCRIPTION OF STRATEGIES
Bryden, J., Traffic Control Handbook for Mobile Operations at Night: Guidelines for Construction,
Maintenance, and Utility Operations. Federal Highway Administration. FHWA-SA-03-036.
August 2003.
Bryden, J.E., and D. Mace, NCHRP Report 476: Guidelines for Design and Operation of Nighttime
Traffic Control for Highway Maintenance and Construction. Transportation Research Board.
Washington, D.C. 2002. http://trb.org/news/blurb_detail.asp?id=1023.
Federal Highway Administration. Manual on Uniform Traffic Control Devices (MUTCD).
Washington, D.C. 2003.
Hanscom, F.N., and R.F. Pain, NCHRP Report 337: Service Vehicle Lighting & Traffic Control
Systems for Short Term and Moving Operations. Transportation Research Board. Washington,
D.C. 1990.
Kamyab, A., T. McDonald, and B. Storm, Synthesis of Best Practice for Increasing Protection and
Visibility of Highway Maintenance Vehicles. Iowa State University Center for Transportation
Research and Education. August 2002. http://www.ctre.iastate.edu/reports/visibility.pdf.
NYSDOT, Highway Design Manual. June 24, 2005. http://www.dot.state.ny.us/cmb/
consult/hdmfiles/hdm.html.
Pratt, S.G., D.E. Fosbroke, and S.M. Marsh, Building Safer Highway Work Zones: Measures to
Prevent Worker Injuries from Vehicles and Equipment. National Institute for Occupational Safety
and Health. 2001. http://www.cdc.gov/niosh/2001128.html.
Ullman, G.L., "Special Flashing Warning Lights for Construction, Maintenance, and Service
Vehicles: Are Amber Beacons Always Enough?" Transportation Research Record 1715.
Transportation Research Board. Washington, D.C. 2000.
19.1 B4--Reduce Flaggers' Exposure to Traffic (T)
General Description
Though many workers are exposed to traffic-related hazards in the work zone, flaggers are
in a particularly hazardous position since they are constantly near moving traffic and
frequently to two or more different streams of traffic. Many times, however, a two-way, one-
lane operation is the only viable traffic control option. Making the flagger more visible
(discussed in Strategy 19.1 B3) is one method to improve flagger safety. Additional
strategies, discussed in this section, include using signals, remote control flagging systems,
and pilot cars.
Road closure is an alternative to using flaggers and two-way, one-lane operations and will
eliminate crashes where vehicles strike flaggers. Refer to Strategy 19.1 A2 for additional
details. Another alternative is use of a temporary roadway that allows for two-way, two-lane
operation.
Temporary Signals
Temporary traffic signals can be used instead of flaggers, thereby reducing the exposure to
traffic of the workers who would perform the flagging task. Temporary signals may be
considered for work zones where other traffic control options include flaggers, stop or yield
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SECTION V--DESCRIPTION OF STRATEGIES
signs, or warning signs or lights. In some situations (such as on low-volume roadways),
these other options may be sufficient.
Work zone types on which temporary signals may be appropriate include:
· Pavement and bridge repair,
· Roadside maintenance, and
· Emergency repairs.
A warrant for the use of temporary signals does not exist, and decisions to use them are
generally made on a case-by-case basis. As with the installation of permanent signals, traffic
conditions and physical characteristics of the work zone should be examined to determine if
use of a signal is appropriate.
Portable Signals
Portable traffic signals can replace flaggers to allow work zone personnel to perform other
critical tasks. In order to avoid fatigue, flaggers need to be relieved periodically, such as
every 2 hours. Workers need to be able to perform multiple functions and need to rotate into
and out of the flagger task. By automating the task of flagging, workers can be freed to focus
on other tasks for longer periods and are removed from direct exposure to traffic at the
flagger station.
Portable signals are mounted on trailers at both ends of the area where one-way operations
occur. Communications between the signals are provided by hard wiring, by a radio
frequency transceiver, or by a preset timing. An operator inputs the cycle information, such
as minimum and maximum green time, yellow and red intervals, and green extension. The
portable nature of the signals on trailers allows for easier setup and removal than stationary
signals, making them an appropriate option for projects of relatively short duration. Portable
EXHIBIT V-17
Portable Signal System to Reduce Flagger Exposure
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SECTION V--DESCRIPTION OF STRATEGIES
signals also may be appropriate for use in long work zones. If temporary signals malfunction
and switch to flashing red operation, drivers must be able to see whether there is another
vehicle on the opposite approach. Portable signals will more likely be used on operations
where workers are present the entire time and where, therefore, flaggers could replace the
signals until the signals are repaired.
Automated Flagger Assistance Devices
An automated flagger assistance device, which is a remote control sign or signal, can be also
be used instead of a flagger. These devices typically require only one worker to operate, and
this worker does not need to be stationed in the roadway or on the shoulder. The FHWA has
issued interim approval for the use of these devices in temporary traffic control zones and
provides technical provisions for these devices (see http://mutcd.fhwa.dot.gov/res-
memorandum_afads.htm). However, each jurisdiction must receive a specific approval from
the FHWA by submitting a written request to the FHWA stating the location where the
device will be used and agreement to comply with the terms.
Approval for use of these devices must be received from FHWA.
There is some concern that drivers will misinterpret the meaning of a remotely controlled
stop/slow paddle. It is possible that a driver will stop at the stop sign and then proceed,
rather than wait for the slow sign. Additional signing could address this.
A brief description of the Minnesota DOT experimental use of such a device is provided on
the FHWA Work Zone Mobility and Safety Program website at http://ops.fhwa.dot.gov/
wz/practices/best/view_document.asp?ID=140&from=topindex&Category_ID=124.
Minnesota limits the use of these devices to work zones less than 1,000 feet long on low-
volume, two-lane roadways. A similar device is a remote controlled red/amber signal that
replaces a flagger or is used in coordination with a flagger positioned out of the traffic
stream. The system includes a gate that lowers during the red signal.
Wisconsin DOT has used a remote flagging device with success; an evaluation is provided
in Appendix 4.
EXHIBIT V-18
Strategy Attributes for Reducing Flaggers' Exposure to Traffic (T)
Attribute Description
Technical Attributes
Target This strategy targets crashes in which vehicles strike flaggers. Other crash types,
such as rear-ends that occur when a driver's view of a flagger is blocked by another
vehicle, may also be reduced.
This strategy is applicable to any work zone where two-way, one-lane operations are
necessary, though some of the alternatives may be more costly than can be
warranted on smaller projects.
Expected Effectiveness While thorough studies have not yet been performed to show the effectiveness of this
strategy, replacing flaggers with temporary or portable signals or remote-controlled
signs would be expected to eliminate crashes where vehicles strike flaggers, should
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EXHIBIT V-18 (Continued)
Strategy Attributes for Reducing Flaggers' Exposure to Traffic (T)
Attribute Description
the flaggers be able to be stationed a distance away from through traffic. It is
possible that rear-end crashes may initially increase as drivers become familiar with
new devices.
Keys to Success If a flagger is replaced with a signal or sign, the traffic control device needs to be
installed and used in such a way that it is clear to drivers what action they are
supposed to take. In addition to advanced warning signs, supplemental signing at the
signal or an arm that lowers during a red phase of a signal (see Appendix 4) to
provide this information, a PI&E campaign may be necessary to communicate to
drivers how the signal operates and how drivers are expected to proceed through the
work zone. This is especially true for the new or experimental systems that are being
developed and becoming more frequently used.
The devices must be visible to approaching motorists, and at least the minimum
amount of sight distance should be provided. Care should be taken to ensure
adequate sight distance to the traffic control device on approaches where permanent
features, such as horizontal or vertical geometry, or temporary conditions, such as
work vehicles and equipment, may restrict the drivers' view of the device.
Appropriate timing of the temporary or portable signals is critical to the success of this
strategy. Excessive wait time can lead to driver confusion and frustration, possibly
resulting in violation of the signal. A maximum reasonable wait time is considered to
be 4 minutes (Daniels et al., 2000, and NYSDOT, 2005). Factors to consider when
determining signal timing include length of the work zone, traffic volume, approach
speed, range of speeds in the work zone, and amount of buffer time between traffic
departing the work zone and traffic entering the work zone (Daniels et al., 2000).
Driveway and intersections, pedestrians, and parking should also be considered
(NYSDOT, 2005).
Potential Difficulties It is important to ensure that replacement of flaggers with remote control of two-way
traffic on a one-way facility does not present greater safety problems for drivers, due
to low visibility of the system or confusion that the new system may create.
Design of a signal timing plan, if it does not consider all appropriate factors, can
negatively impact traffic flow and safety through the work zone. Conditions at the site
should be studied before implementing the signal.
In the event of malfunction of a traffic signal or of an automated flagging device,
flaggers must take over responsibility of directing traffic immediately. It is possible that
work zone personnel would not be immediately aware of the malfunction unless
stationed nearby and watching for such situations or unless the system has an alarm to
warn workers that there has been a malfunction. Such an issue could result in serious
head-on crashes as well as place workers within the area at greater risk to collision.
As with traditional manual flagging operations, work zones with driveways or
intersections in between the signals or automated flagging devices will present
additional challenges to safe handling of the alternating one-way operations. It is
preferable to locate the one-way operations so that they do not include intersections
and high-volume driveways so that automated flaggers or portable or temporary
signals are controlling all the vehicles that enter a work zone.
For work zones that involve very short-term, one-way operations or projects with a
location that moves frequently, flaggers may be a better choice than temporary or
portable signals, since the benefits gained by using portable signals may not be offset
by the repeated efforts to set up, take down, and move the signals.
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EXHIBIT V-18 (Continued)
Strategy Attributes for Reducing Flaggers' Exposure to Traffic (T)
Attribute Description
Appropriate Measures A key process measure is the number of projects on which flaggers are replaced with
and Data temporary or portable signal systems or with experimental remote control flagging
systems. Documentation of the type of system and the manner in which it is deployed
is also needed as part of the process evaluation data collection.
Key safety effectiveness measures include crash frequency and severity, by type of
crash. It is important to consider crashes involving flaggers in the work zone.
Crash frequency and severity data are needed to evaluate the construction operation
for safety effectiveness. Traffic volume data are needed to represent exposure. Delay
data are needed to determine the operational impacts of the project on traffic flow.
Associated Needs A PI&E campaign is an important part of implementing a device for controlling two-
way, one-lane operation that may be new or potentially confusing to drivers. Drivers
need to know how to respond when they encounter the situation, especially if it is
relatively new to an area. It is important to communicate with the public on the use of
remote control flagging systems, as these are experimental and it is very likely that a
high percentage of drivers will not be familiar with them.
Organizational and Institutional Attributes
Organizational, Agencies using temporary signals need to determine whether alterations to the
Institutional and procedure for adjusting the timing of temporary signals are needed. While temporary
Policy Issues signals are in use, agencies will want to establish a procedure for adjusting the
settings. It should be determined who will be responsible for determining the changes,
and it is important to consider how this will be accomplished during nonbusiness hours
if the signal will be operating at night.
An agency desiring to use this strategy may need to develop a set of policies and
guidelines on the use of the devices. In some cases, legislation may be needed for a
control device to be used. Another key issue is the development of operational
procedures for these devices to ensure that each setup provides adequate sight
distance. Proper signal timing for specific temporary and portable signals should also
be determined using established policies or guidelines.
Since remote control flagging systems are experimental traffic control devices, FHWA
approval may be needed before they can be used. An evaluation plan should be in
place as well to assess the effectiveness of the system.
Issues Affecting Implementation of temporary or portable signals or remote control flagging systems
Implementation Time can be achieved in a relatively short time, once any necessary authorization is
received. The "authorization," however, may involve passing legislation, establishing
policies and guidelines, and receiving FHWA approvals. In such cases, the time could
be extended to beyond a year.
Costs Involved The cost of the improvements and devices described above could be amortized over
several projects. To implement such measures in all applicable locations would have a
significant impact on overall budget and cost of projects. Many agencies will purchase
one or more sets of equipment and use these sets on projects where they will provide
the greatest benefit. One advantage to having several of these systems is that by
freeing a flagger to perform other tasks, efficiency is increased on the project and the
number of personnel needed is reduced.
Example costs of a temporary signal are provided in Appendix 5.
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EXHIBIT V-18 (Continued)
Strategy Attributes for Reducing Flaggers' Exposure to Traffic (T)
Attribute Description
Training and Other Highway agency personnel (specifically traffic signal engineers) and contractors
Personnel Needs should be trained in the process of developing a signal timing plan for temporary and
portable signals (including appropriate location of the devices in order to ensure
adequate sight distance) and use of the system, as appropriate for the tasks for which
the personnel are responsible. Training will also be needed for flaggers who are
operating remote control systems and proper procedures for serving this function.
Legislative Needs None identified.
Other Key Attributes
Compatibility of Use of temporary or portable signals or remote control flagging systems is compatible
Different Strategies with other strategies discussed in this guide.
Key References
Bryden, J.E., and D. Mace, NCHRP Report 476: Guidelines for the Design and Operation of
Nighttime Traffic Control for Highway Maintenance and Construction. Transportation Research
Board. Washington, D.C. 2002. http://trb.org/news/blurb_detail.asp?id=1023.
Daniels, G., S. Venglar, and D. Picha, Feasibility of Portable Traffic Signals to Replace Flaggers
in Maintenance Operations. Texas Transportation Institute. TTI Report 3926-1. 2000.
http://tti.tamu.edu/documents/3926-1.pdf.
Federal Highway Administration, Manual on Uniform Traffic Control Devices (MUTCD).
Washington, D.C. 2003.
McGraw-Hill Construction, "Illinois to Test Flagging Device as Part of Injury Crackdown."
Engineering News-Record. The McGraw-Hill Companies, Inc. March 15, 2004. Vol. 252,
No. 11. Page 16. http://72.14.207.104/search?q=cache:odfwtpJcUY0J:www.enr.com/
news/safety/archives/040315.asp+Illinois+to+Test+Flagging+Device+as+Part+of+Injury+
Crackdown&hl=en.
Notbohm, T., Evaluation Report on RC Flagman Remote Flagger. Wisconsin DOT. June 2004.
See Appendix 4.
NYSDOT, Highway Design Manual. June 24, 2005. http://www.dot.state.ny.us/cmb/
consult/hdmfiles/hdm.html.
Information on Current Knowledge Regarding Agencies or Organizations
That Are Implementing This Strategy
Texas DOT has used portable signals on several projects. Use of the signals is evaluated by
Daniels et al. (2000).
Washington DOT has identified Unilight traffic signals as a top-rated ITS application to avoid
stationing flaggers close to traffic (http://www.betterroads.com/articles/brjun00c.htm).
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