Technology Driven

Jan. 10, 2007

The evolution of technology in roadway construction zones can be found in products ranging from giant screens displaying real-time traffic information to tiny, microscopic prisms that reflect an amazing portion of light back to the driver, marking the traffic route more clearly.

Though many changes may not be apparent to the casual driver, work-zone safety and mobility have gone high-tech in recent years in an effort to reduce congestion and help roadway users and workers remain safe during driving conditions that are sometimes hazardous.

The evolution of technology in roadway construction zones can be found in products ranging from giant screens displaying real-time traffic information to tiny, microscopic prisms that reflect an amazing portion of light back to the driver, marking the traffic route more clearly.

Though many changes may not be apparent to the casual driver, work-zone safety and mobility have gone high-tech in recent years in an effort to reduce congestion and help roadway users and workers remain safe during driving conditions that are sometimes hazardous.

In the transportation construction industry, we often think of intelligent transportation systems, or ITS, when we talk about integration of high-tech innovations on roadways. These applications include cameras, sensors and other input devices; automated data processing; and output devices such as dynamic message signs, websites and highway advisory radio. But ITS devices are only a portion of the technology revolution that is changing everything from pavement markings to the seemingly low-tech barricades and crash cushions.

The American Road & Transportation Builders Association (ARTBA) and members of its Traffic Safety Industry Division (TSID) are world leaders in developing and deploying some of these cutting-edge technologies. The following are a few examples of how improved technology is making work zones safer for all who may enter.

Future of retroreflectivity

In April 2006, 3M introduced a new high-build resin for pavement markings to increase durability and provide an all-weather optics system that performs in wet and dry conditions. The all-weather paint provides bright pavement markings, even when a roadway is drenched with water.

Traffic paint is the most commonly used pavement marking in the world; it is inexpensive and easy to apply. But government agencies are not always happy with the trade-offs they are forced to make in durability and visibility. With conventional paint, agencies must re-stripe more frequently than they would like, meaning workers are more often at risk and motorists are more frequently inconvenienced. This new, all-weather paint incorporates a high-build resin that enables the paint to be applied thicker thus increasing the life of the paint.

The resin also helps to hold retroreflective optics. This new product contains a unique dual-optics system that enhances dry and wet reflectivity. As weather conditions change, the wet or dry reflective components automatically take over, enabling the paint to provide guidance in all weather conditions.

3M also recently introduced Diamond Grade DG3 reflective sheeting for signs, which uses state-of-the-art, full-cube technology to deliver optimal performance where and when drivers need it most.

Several factors render much of today’s installed signage less effective in providing the visual guidance drivers need.

New auto headlight designs with their low horizontal beams reduce the visibility of signs. Diverse vehicle sizes—from cars to SUVs to semi-tractors—create vastly different observation angles. These changes in automobile design and preference require improved signage.

The new reflective sheeting has optical elements that are 100% efficient, returning almost 60% of available light—nearly double that of traditional prismatics. It performs at all sight distances, including short and medium, and where signs are positioned in disadvantaged locations such as overhead or on the left shoulder.

New to the U.S. market is Reflexite Americas’ retroreflective checker tape for use on garments worn by fire fighters, emergency responders, state DOT personnel and law enforcement officers who may be called upon to work adjacent to traffic in all weather conditions and at any time of day. These workers can now be identified by service with 24-hour visibility through a technology that is weather and solvent resistant. The tape has a smooth sealed outer surface that provides bright and safe high-visibility protection at night and in adverse weather conditions. The enclosed optical system allows trim to retain nearly all its reflectivity even when drenched with rain.

This Reflexite GP 800 Checker Tape is available in four color combinations, internationally identified as the colors associated with police (blue), emergency services (green), fire (red) and state DOT first responders (orange). In Europe and in the U.S., major efforts are under way to help the public recognize colors associated with the various emergency response agencies.

Talking roads

Through use of improved ITS technologies, roadways literally evaluate conditions and talk to motorists without human intervention, saving time and lives. This is particularly important in work zones, where conditions can change abruptly and unexpectedly.

Technologies are now available allowing roadside computers to operate autonomously to collect and analyze data, make decisions regarding what messages to display and automatically update portable changeable message signs (PCMS), radio messages and websites to reflect the traffic conditions.

In one application, a dangerous hydroplane situation existed at a bridge replacement work zone where the project required eight lanes of temporary pavement to detour traffic. After the temporary lanes opened, over 50 incidents were reported, many of which were attributed to water on the roadway during heavy rains. To solve the problem, North Carolina DOT deployed an automated hydroplane detection and alert system developed by Quixote Transportation Safety with pavement sensors that measure water. When the pavement was dry, the PCMS was blank. When the pavement was lightly wet the displayed message was, “Wet Pavement Ahead; Observe Speed Limit.” When water depth reached 6 mm, the displays automatically changed to state, “Standing Water Ahead; Reduce Your Speed.” After deployment, no accidents were reported due to wet pavement conditions.

International Road Dynamics has successfully deployed another technology to allow for safer lane merging in work zones—a common site of accidents. This lane-merge system provides both “early merge” and “late merge” instructions, automatically controlling traffic flow and dangerous merge areas on tapered approaches.

The early merge system uses a series of trailers with microwave radar sensors to read traffic flow. On cue, lights flash on signs that read: “Left Lane Do Not Pass When Flashing.” Based on vehicle congestion, the dynamic work zone expands and shrinks creating a “No Passing Zone” prior to the construction zone. The system instructs motorists to merge early to prevent backups that often occur when drivers wait until the last minute. The late merge system works on the same principles, but encourages drivers to merge later rather than earlier. When traffic congestion builds, electronic message signs instruct drivers to merge just prior to the construction taper.

Computer eyes

Technologies for collision warning and protection of workers on foot are generating a lot of interest from contractors, government agencies and labor groups. Despite genuine interest in worker safety at virtually every heavy construction firm, the U.S. Bureau of Labor Statistics documents scores of fatalities and thousands of injuries each year caused by workers being struck by vehicles and equipment.

Several technologies are being refined for use of onboard computing, communication and display capabilities for heavy equipment that will alert operators to the presence of nearby pedestrian workers and other hazards that may not be apparent. Tag Safety Systems is perfecting processing hardware to detect workers and alert drivers and operators when workers on foot are present. Such systems are likely to become standard equipment on everything from fork lifts and dump trucks to cranes and excavators. In addition to collision warning devices, future vehicle electronic safety systems can include tip-over monitors, computer control of machine movement under heavy loads, vehicle status monitors, fleet management network connections, logistics and supply chain information systems and other features.

As standard original equipment, such electronic systems will have much greater customer acceptance than after-market installations, since sensing, computing and display hardware can be shared. In this way, new worker protection technologies will share costs with other onboard systems, and each will represent a relatively small cost increase to the base machine price.

Absorbing danger

In April 2006, Energy Absorption Systems introduced a new trailer-mounted attenuator (TMA) to protect workers from passing traffic while minimizing potential damage to the host construction vehicle (to which TMAs traditionally have been directly attached). The unique design of the SST Safe-Stop Truck Mounted Attenuator requires minimal modification to host vehicles allowing quick and simple attachment, resulting in low installation and operating costs, as well as increased truck fleet operating flexibility.

When impacted, the unit’s steel support frame collapses and the aluminum cartridges crush to absorb the energy of impact, bringing the impacting vehicle to a controlled stop.

Another important feature of the TMA is anti-rotational dampeners that are designed to lock the TMA in place during an angled impact to maximize the TMA’s effectiveness and minimize the impacting vehicle’s ability to enter a work zone or adjacent lane, which could cause a secondary accident. The dampeners also protect the host truck’s frame by spreading the load of the impacting force and providing maximum protection to work crews, the impacting driver, adjacent drivers and the host vehicle. An optional arrow board attaches directly to the device.

Take it wherever you work

A recent study by the Texas Transportation Institute concludes “highly portable positive protection technologies” are a cost-effective means to protect workers when other types of portable concrete barrier cannot be cost-effectively deployed for short-term projects.

A barrier is now available from Barrier Systems Inc. that uses reinforced steel sections to create a freestanding portable barrier that can be easily moved as the work zone moves. When in place, sections of the SafeGuard Link barrier can be opened and closed without difficulty to permit construction and maintenance vehicles to pass through.

Individual sections of the barrier can be loaded and unloaded without heavy equipment, and each segment has integrated wheel assemblies that are lowered and raised by a built-in hand crank or optional compressed-air system.

With the wheels down, the system can be easily moved to reconfigure the work area. The barrier system also can be slowly towed or pulled down the roadway to move with the work zone during construction operations. This technology now allows deployment of positive separation between workers and motorists when traditional concrete barriers are not feasible.

Taking it slower

Recent studies have demonstrated that the introduction of new technologies into roadway work zones are having a positive effect on motorists, with over 70% indicating they slow down when they see speed advisories. In another study, well over 50% of drivers opted to change their routes on occasions when they received messages about work-zone-related delays, especially when the messages contained specific information about exits and alternative roads.

About The Author: Sant is vice president of safety and education for the American Road & Transportation Builders Association, Washington, D.C.

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