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Active traffic management increases safety and capacity

First publishedin ITS International
2010 July August
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Smarter Highways
Smarter Highways is intended to increase roadway capacity by 22 per cent and reduce the number of collisions by 30 per cent

WSDOT is deploying Active Traffic Management in order to increase safety and capacity on its strategic roads. WSDOT's Patricia Michaud elaborates

WSDOT is deploying Active Traffic Management in order to increase safety and capacity on its strategic roads. WSDOT's Patricia Michaud elaborates

To enhance economic vitality and personal mobility while safeguarding the environment, Washington state must continually improve its transportation system. A balanced, efficient and reliable transportation system can meet increasing population needs and allow the state to stay competitive in a global economy for years to come.

Moving Washington, the state's congestion relief programme, provides both the tools and the blueprints to meet these goals. This state-wide solution uses technology that will strategically add new capacity and expand the range of commuter choices. New techniques will be used to make highways more efficient and better prepare the transport system to cope with increasing demand.

Smarter Highways and Moving Washington

Making highways smarter is a key element of Moving Washington. WSDOTS's Smarter Highways system incorporates many elements of what is known more widely as Active Traffic Management (ATM).

WSDOT is activating its first Smarter Highways system on northbound I-5 in south Seattle in August 2010. A key aim is to help keep people and goods moving during construction to replace the Alaskan Way Viaduct. WSDOT is also introducing Smarter Highways on two other busy corridors in the Puget Sound region: both directions of I-90 and SR 520 between Seattle and Bellevue. That amounts to about 40 miles of roadway for all three corridors.

Smarter highways will improve safety, reduce the number of collisions and reduce congestion by automatically alerting drivers to changing road conditions. Overhead electronic signs will give drivers advance notice of incidents on the road ahead and reduce the number and severity of collisions associated with congestion. Slowing down drivers before they reach the point where the traffic stops will prevent the panic braking that can lead to collisions.

Depending on traffic conditions, drivers may see varying speeds, the default 60 mph, alerts, arrows or blank signs.

WSDOT expects this new technology to save $6.8 million each year in emergency response service costs and driver delays. But most importantly, Smarter Highways will reduce the number of people who are injured or killed. For example, northbound I-5, between Boeing Access Road and I-90 in south Seattle, carries an average of over 100,000 verhicles per day. Drivers are involved in an average of 459 collisions per year within this 7.3 mile corridor and on weekdays between 5.00am and 7.00pm there are an average of 306 rear-end and sideswipe collisions per year.

Washington is one of the first states to introduce this cutting-edge technology. Minnesota introduced some ATM tools to its road users last year. Both systems are based on technology used in Europe for the past two decades.

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Telegra matrix signs
Telegra is delivering four types of full-matrix signs which between them will give drivers all the information they need to take advantage of ATM

Telegra's role

Elcon Corporation, DKS Associates, Inc., and Telegra formed a collaborative alliance that offered WSDOT a fully integrated project designed to meet all the stated WSDOT goals and requirements. Telegra's high-tech Dynamic Message Signs (DMS) form the most visible part of the I-5 ATM system. The company's extensive experience of DMS best practice in both Europe and the US was essential when creating a synergy between the most demanding requirements of EN 12966, NEMA TS4 and NTCIP standards and developing a state-of-the-art Light Emitting Diode (LED)-based sign system.

High-tech electronic signs

The DMS are manufactured as full-matrix displays and supplied in four different types: overhead Lane Control Signs (LCS); Side-mount Dynamic Message Signs (SDMS); and overhead Variable Message Signs (VMS) in two different sizes.

All of the DMS and their communication capabilities are fully compliant with NTCIP and NEMA TS-4 standards. Quality of manufacture ensures an in-service life of at least 10 years and their low cost of ownership over an extended lifetime has been further improved by requiring the same set of spares (supplies, controllers and LED boards) for all unit types. The systems are constantly self-checking; this includes ensuring that the message is intelligible to road users.

Telegra's high-performance proprietary optical system and LED display result in a high contrast ratio, providing for excellent visibility under any external lighting conditions. The innovative LED current drive technology reduces power consumption by up to 30 per cent for a given luminance, thus extending overall sign life.

The LCS are full-colour, full-matrix RGB signs that are mounted on a gantry over each traffic lane and use symbols (red crosses, green arrows, left and right yellow merge arrows) to inform motorists of lane closures/openings and variable speed limits. The SDMS are also full-matrix, full-colour RGB displays that mount on a gantry leg and warn drivers of potentially dangerous situations downstream by displaying appropriate symbols or text messages. The VMS are full-matrix, amber displays used to inform road users of the current situation ahead through text messages. Full-matrix displays allow full flexibility and the use of various text sizes and font types. New symbols of any type and colour can be easily added and implemented.

Sign control

A modular sign controller with common touchscreen user interface supports all signs on one gantry, resulting in reduced costs and reduced field cabinet space while providing enhanced sign status communications and diagnostics. The controller supports up to eight NTCIP sign controller modules, with plug-and-play capability enabled by auto configuration that can be fitted in one 2U 19in rack providing free space for additional traffic-related equipment such as CCTV, weather monitoring, traffic counting and so on.

International expertise

Telegra's experience is seen as essential to the implementation of ATM on the I-5. A leading manufacturer of DMS since 1989, Telegra has delivered over 3,000 state-of-the-art LED signs and related support systems worldwide. Among its worldwide projects portfolio, one of the most representative is the implementation of a VMS and LED display system in Hungary for M0 Budapest orbital. This project included delivery of approximately 300 RGB displays and full-matrix yellow text displays in a very short period of time to the full satisfaction of the end user.

In 2007, Telegra implemented an ATMS on the Kiev-Borispol section of the Kiev-Kharkov highway. This included over 100 fully programmable RGB displays, fully programmable text displays, meteorological stations, non-intrusive overhead traffic counters/classifiers and CCTV cameras, together with roadside controllers and associated network equipment. Also included in the delivery were hardware and software for traffic management at the Operations and Maintenance Center (OMC) in Kiev. The complete section is controlled by Telegra's topXview SCADA traffic management. Both GUI and application notes were delivered in Ukrainian, the local language.
A unique Graphical User Interface (GUI) serves as a common user interface for all sign controller modules, enabling an easy approach to all of the sign's functionalities through interactive menus on an LCD touchscreen. The GUI emphasises real-time message monitoring in WYSIWYG format with preview and active messages. This allows monitoring and/or control of all of a sign's sensors, heaters, fans, incoming power supply, LED power supply, door status and much more.

The controller features a main communication module for single modem connection to a control centre and is equipped with an Ethernet switch and optional redundant UPS for sign controllers. The applied Sign Quick Mounting System results in simplified installation and subsequent movement; it also results in minimal traffic disruptions and driver inconvenience during maintenance.

Sign testing

To ensure compliance with specifications, quality, reliability and performance within the local Advanced Traffic Management System (ATMS), WSDOT staged three levels of signage testing. Upon delivery, signs underwent a 30-day testing process during which WSDOT staff inspected compliance with RFP, overall quality and functionality. After passing that, signs were installed on gantries and connected to the local ATMS for an additional 20 days of testing. The second stage of testing ensured proper and reliable communications between WSDOT's traffic management centre and all signs. Finally, before going live, a 60-day test of all components of the ATMS was conducted to ensure functionality of the system as a whole.

System go-live

Once the system is activated in August of this year, I-5 commuters will experience safer and smoother traffic on a roadway that detects changing traffic flows and automatically adapts to traffic congestion by adjusting the speed limits and providing drivers with useful traffic information. The signs will display speed limits from 40 to 60 mph, depending on traffic levels. A 30 per cent reduction in collisions is targeted while roadway capacity is expected to increase by 22 per cent.

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