Electric Signs on US Roads

Whether on the way to a major sporting event, opening night at the theater or going home for the holidays, drivers rely on road signage for the critical information required to get them where they want to go. The more effective a road sign is at communicating its message, the safer the roadway will be.

While static signs serve a definite purpose, dynamic message signs (DMS) provide more flexibility in the instructions that can be relayed, with real-time information enabling drivers to make more appropriate decisions. And while they have been used for some time in Europe, it is only recently that they have found widespread use in the US, at construction zones, special events and on major thoroughfares where they are used to notify drivers about accidents, general congestion, parking instructions, weather advisories and more.

Until recently, however, the effectiveness of these signs has been somewhat limited because of the monochromatic text messages they provide.

Living colour

There is evidence that the addition of colour and graphics to DMS messages improves the response of drivers, thus increasing the value of the signs for communication of important messages. Researchers at the University of Rhode Island found that the use of graphics in particular resulted in faster response times, with the elderly and non-native English speakers benefiting the most.

Colour alone is an improvement over monochromatic displays. In the US, the colour of a static sign is recognised to have a certain meaning: orange = construction; yellow = directional; brown = historic; and blue = informational. "With colourful DMS messages, these meanings can be reinforced," notes Carl Defebo, a spokesperson for the Pennsylvania Turnpike Commission.

Adding graphics that replicate the images seen on well-established static signs further enhances the effectiveness of DMS messages.

"People who can’t read quickly can readily see the graphic and recognise what it stands for. Having both a graphic and text helps ensure that drivers will have no trouble understanding the message," Defebo says.

So why haven’t colour and graphics been used until recently? According to a spokesperson from for Daktronics, a manufacturer of dynamic message signs based in South Dakota, one possible reason for their slow adoption could be due to the fact that the national standard for DMS in the US has not addressed this issue.

"The second version of NTCIP 1203 for DMS (National Transportation Communications for ITS Protocol) should be formally released in the near future. This version incorporates standards for colour and graphics used in DMS," ITS market manager Casey Crabtree says. He says he expects the release of the new standard to drive growth in demand for colour and graphics in electric signage in the US.

If the experiences of early users of the advanced DMS technology are any indication, Crabtree is correct. Whether the colourful signs have been used to direct traffic in city centres or at toll plazas on major highways, the results have been positive, both for the installers and their customers.

Major events

Governments in both Roseville, California and Dallas, Texas have used full colour dynamic message signs to direct traffic in areas where special events are held and to provide real-time information to drivers on arterial roads leading to major highways.

In Roseville, a city of about 110,000, permanent signs were installed in several locations where community-wide events such as parades take place, requiring the blockage of thru traffic lanes leading to freeways.

"We wanted to make these signs stand out because they are for special occasions. The ability to include a full spectrum of colours and graphics really makes the signs noticeable," Richard Fowler, associate engineer with the City of Roseville Department of Transportation says.

For example, if an event has its own logo, the city can incorporate that logo into the sign along with the appropriate directional message. In addition, they no longer require portable signs that need to be modified for each event.

In Dallas, a much larger city, the full colour signs are mainly used in Fair Park, where the state fairgrounds, the Cotton Bowl football stadium and several museums and concert venues are located.

"There is a lot going on in this area, and the ability to have different coloured signs that are keyed to different events has really helped improve traffic flow," traffic systems programme manager Mark Titus says. The city also targets different types of drivers using colour – and in some cases – a common graphic, such as the use of blue and white and the well recognised handicapped symbol for directing people to easy access parking.

Full-colour DMS have also been useful on arterial roadways leading to freeways. The messages on the signs inform drivers of incidents on the highway and may suggest alternate routes or provide other information. The symbol for an interstate roadway is sometimes used to emphasize that the sign is relating to the major thoroughfare.

A third application in Roseville, and one that the City of Dallas is exploring for the future, is the use of these colourful signs to display messages such as Amber Alerts about missing children or tell people to "Buckle Up" or "Don’t Drink and Drive". Having access to an array of colours makes it possible to distinguish these advisory messages from directional ones.

Roseville will also be integrating the colour signs with a new traffic monitoring system that features detecting loops embedded in the roadway with field traffic counting abilities. Provided by Naztec Solutions, the operating software will send an alert to the DMS if it detects congestion, which will trigger the display of an appropriate message.

Toll booths

Congestion can also be an issue for toll roads, particularly at toll booths where drivers enter and exit the highway. In fact, the majority of accidents that occur on toll roads happen near toll plazas, as people look to find change while trying to determine which lane to be in.

The search for a signage system to improve communication at toll plazas and make more efficient use of the lanes led both the North Texas Toll Authority (NTTA) and the Pennsylvania (PA) Turnpike to try electric signage with full colour and graphics capabilities.

"As drivers are entering and exiting toll roads, they are faced with more lane choices now than in the past. Colour and graphics in a DMS allows us greater flexibility and a more effective means of getting important information to our customers," Defebo says.

Civil engineering firm Lamb-Star Engineering’s Eric Starnater says the NTTA controls the programming of the signs from a central point.

"Each sign has its own IP address and acts like any other computer on the network, or it can be controlled through the lane control system, making it very easy to make changes in response to real-time activity on the roadway."

The ability to use full-colour graphics to mimic existing static signage has been beneficial as well.

On the Pennsylvania Turnpike, drivers can have a choice of up to four different lane types as they enter and exit the toll plaza. The DMS design allows the agency to use just one sign for all eight different messages, providing greater flexibility, according to Defebo. Control of the signs is located at the toll booths for this system.

The choices on entering the highway include Ticket Only, EZ Pass No Ticket, Ticket or EZ Pass and Lane Closed. Exit choices are similar: EZ Pass No Cash, Cash Only, Cash or EZ Pass, and Lane Closed. EZ Pass is the electronic toll collection system used throughout the Northeastern US.

Graphics are used for the purple EZ Pass logo, with green for Cash Only and red for Lane Closed. The combination of EZ Pass logo and "No Cash" text (in yellow) ensure that drivers who aren’t familiar with the system will still understand the directions.

So far the full colour dynamic message signs have been installed at four different toll plazas on the PA Turnpike that have been reconstructed in the last three years.

"We are pleased with the results of the pilot programme," notes Defebo. "The signs are brighter and more visible both in the daytime and at night, and they can be seen further from the plaza than our older prismatic signs."

Based on this, it seems that the predictions generated from laboratory simulations were indeed correct. As a driver in the US, I can only hope that more transportation agencies will recognise the value of colour and graphics in dynamic message signs and begin using them in the near future.