If you drive regularly along Route 100 in Howard County, you might notice the lighting is a little dimmer than it used to be.
In an effort to save energy and money, the State Highway Administration has cut back its overhead lighting on a six-mile stretch of the highway. If results from the year-long test are favorable, officials say, the state could reduce lighting on other highways.
Maryland is one of many state and local governments seeking savings on highway lights, said John Bullough, senior research scientist at the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y.
"It's something that people are looking at in terms of reducing cost — no doubt," Bullough said.
According to state highway officials, about 75 lights along Route 100 between Coca-Cola Drive and U.S. 29 have been "deactivated" as part of a pilot project to evaluate whether the state can cut its power use along state roads without compromising safety.
Altogether, SHA spokesman Charlie Gischlar said, 20 percent to 25 percent of the lights along the six-lane, interstate-style roadway have been turned off.
For now, the light poles remain in place. But if the test is successful, the state might remove them and recycle them to other locations. The primary aim, Gischlar said, is to reduce energy consumption as a "green" initiative. But he said any cutback in energy use could also yield savings in operating costs.
The experiment has raised concerns about safety in some quarters. For many motorists, a well-lit roadway is comforting, and many studies over the decades have shown that bright lights — in the right places — can save lives.
Highway officials said that even with fewer lights, the illumination of Route 100 will remain well within federal standards. But AAA Mid-Atlantic still has concerns about the test.
"With the nation's motorists aging rapidly, we need to keep in mind they tend to have more difficulty seeing to drive safely at night. We worry that deactivating highway lighting could curtail motorists' safety," said AAA spokeswoman Christine Delise.
Delise said AAA is urging the state "to proceed very cautiously" and to monitor the safety effects of the change.
"Obviously should there be any uptick in crashes during the test period, we expect SHA to abandon the program. Maryland may be saving money on lighting but one fatal crash will offset any savings," Delise said.
But Gischlar said safety is one reason for the experiment. If the state can reduce the lighting, it can also cut the number of poles that vehicles can run into, he said. Collisions with fixed objects such as light poles and trees are one of the most common types of fatal crashes on the nation's highways.
He said Route 100 was chosen largely because it is a relatively new road — opened in the late 1990s — where the lighting exceeds federal requirements.
Gischlar said the state is keeping the lighting at past levels at certain "decision points" — near interchanges, bridge and curves — but cutting back in other places.
Highway engineers are confident they can reduce lighting without any negative impact on safety because modern headlights are much more advanced than the "glorified flashlights" that were on cars when federal lighting standards were originally set, he said. The reflective quality of road signs and other markings also has improved in recent decades.
Some experts in highway lighting say recent research suggests a brighter highway is not necessarily safer.
Bullough, a member of the national Transportation Research Board's Committee on Visibility, said lighting has been shown to cut the number of crashes at "conflict points" where traffic comes together. But between those points, he said, "there really wasn't a large relationship between lighting and reduction in crashes."
The benefits of lighting might not be as great on limited-access roads such as Route 100, Bullough said.
"You're talking about very well-marked, well-delineated, well-channeled roadways," he said. "In general, what we found was the less potential for conflict you have, the less relationship between lights and safety there seems to be."
Bullough said roughly 20 percent of the country's roadways have lights; 80 percent do not. "It must not be a complete disaster. Otherwise, it would be the other way around."
Gene Hawkins, associate professor of civil engineering at Texas A&M University, said transportation departments have had to re-examine past practices during an era of budget austerity.
"Agencies have had to look at the service they provide and whether those services provide the appropriate value," he said. "The potential savings are in the hundreds of thousands of dollars — if not the millions for a state — depending on how aggressively and widespread they pursue it."