BOSTON -- Subtle tweaks to traffic lights can pay big dividends for commuters, according to a nationwide study released this week.

It's all about the timing. Done right it means less congestion and less pollution.

NewsCenter 5's Bianca de la Garza reported that idling in downtown Boston has some drivers seeing red.

"It takes too long to change," one driver said.

A new study grading the timing of traffic signals gives our country a D grade, finding the vast majority have the potentially for greatly improved performance.

"You can see the delays, drops of 20 percent just by making adjustments to your existing signal timings," Howard/Stein-Hudson Associates Jim Danila said.

Danila is working with the city on retiming lights in the Back Bay.

"We are trying to make it so that people are not going from a green light to a red light, from a green light, to a red light," he said.

Inside Boston's City Hall, cameras monitor traffic intersections.

"From this control center, we can change the timing of over 400 traffic signals in the city -- as far out as Hyde Park," Boston Transportation Commissioner Tom Tinlin said.

The study said that Austin, Texas, made improvements and saw its delays drop 10 percent, saving commuters 2.3 million hours of their time and 1.2 million gallons of fuel usage.

Tinlin said that Boston is investing millions in upgrades.

"On a Friday night, when everyone is trying to get down the Cape in July, I think folks would say we are in that national D category. But, I think that in downtown, day-to-day, that we are doing a good job," Tinlin said.