The daily misery for thousands of drivers who travel through one of Montgomery County’s most congested intersections has grown noticeably worse lately because of one change: A left-turn lane is missing, courtesy of the new Intercounty Connector.

Traffic engineers have rated Georgia Avenue and Norbeck Road — a major crossing point among Olney, Rockville and northern Silver Spring — as “failing” for years. But residents say the problems have multiplied since late March, when the state converted one of northbound Georgia’s two left-turn lanes into a third through lane. State officials say they are trying to make the entire intersection operate more efficiently while helping drivers reach the ICC entrance farther north on Georgia.

While the ICC’s environmental impacts were debated for decades, its effects on the crushing loads of local traffic are just now being felt. The six-lane toll highway’s first 7.2-mile segment opened between Interstate 270 and Norbeck, just east of Georgia, in late February. The rest of the 18.8-mile road stretching east to Interstate 95 in Prince George’s County is scheduled to open by next spring.

With more than 85,000 vehicles traveling through the Georgia and Norbeck intersection daily, drivers say the queue in the single turn lane overflows regularly into northbound Georgia’s through lanes. Left-turning drivers trying to squeeze through the intersection on the single green arrow run red lights.

Some residents say the quiet neighborhood streets nearby have become rush-hour thoroughfares clogged with commuters trying to avoid the bottleneck.

Several homeowner groups, including the Greater Olney Civic Association representing nearly 10,000 houses, are planning to hold a rally at the intersection at 5 p.m. Wednesday.

“We were told the ICC wouldn’t make it worse,” said state Sen. Karen Montgomery (D), whose district includes nearby neighborhoods, “and it’s making it worse.”

Montgomery said she decided to join the rally after her office received more than 100 complaints — an unusually high number for even the most hot-button political issues. She said it took her nearly three light cycles to turn left one recent evening. “When you have over 100 people complaining about one turn lane being removed,” Montgomery said, “that’s something I need to respond to.”

One recent day at 5 p.m., 16 vehicles waiting to turn left protruded into northbound Georgia’s left through lane. It took two cycles of the light to make the turn. After one cycle, the last three vehicles ducked through the intersection on a red arrow. By then, the left-turn lane was already half full with eight vehicles that had missed the light.

Melinda Peters, the state’s ICC project director, said Maryland has planned since 2008 to convert one of the two left-turn lanes into a third through lane. She said the community had raised concerns that Georgia would become clogged with traffic trying to reach the ICC entrance just north of Norbeck.

The state also built a temporary eastern terminus for the ICC’s first segment beyond the intersection until the full highway opens to spare it more traffic, she said.

Changes made to the intersection help it function the best it can in all directions, Peters said. While northbound Georgia lost a turn lane, for example, westbound Norbeck heading south onto Georgia gained a new one.

The state offset Georgia’s lost second turn lane by making the single green-arrow light longer, she said. That enables all vehicles to clear the left-turn lane within one light cycle “a majority of the time,” Peters said.

The intersection, she said, “is operating as efficiently as it possibly can, recognizing it was and continues to be a failing intersection.”

“Failing” means the number of vehicles outstrips the intersection’s capacity, leaving it with regular traffic jams. Maryland has plans — but no money — to build an interchange there. For now, Peters said, the state will continue to monitor it daily and work with the county to fine-tune signal timing, both at Georgia and Norbeck and at other intersections nearby.

There is enough room to return a second turn lane to northbound Georgia, she said, but state highway officials don’t believe it’s necessary. Moreover, Peters said, doing so would hinder traffic going in the other three directions.

Ironically, the ICC itself continues to have an empty feel, even during rush hours. Cheryl Sparks, spokeswoman for the Maryland Transportation Authority, which operates the ICC, said the average weekday traffic count — about 11,000 vehicles — is on par with the 10,000 vehicles the state expected daily about two months after opening. As drivers discover the road over the next three years, the state expects 21,500 vehicles will use the first segment daily, Sparks said. About 55,000 vehicles are expected to eventually use the entire ICC each day, she said.