SMYRNA - Beginning Monday, northbound lanes on Cobb Parkway between Spring Road and the Clock Tower just south of Windy Hill Road, will be reduced to a single lane as Georgia Power begins upgrading and installing power transmission lines in Cobb.

The company will be erecting 125-feet tall metal transmission poles for the project from 9 a.m. to 4 p.m. weekdays. There will be about 15 new poles installed in that 2-mile stretch of roadway from Spring Road. One pole a day will be installed, the company reported, which means the project will take up to two weeks to complete.

"We're not going to block the whole lane for the entire distance," said Georgia Power spokesman John Sell. "We're going to block it as we do a pole."

Beginning Oct. 19, Georgia Power plans to erect an additional five poles along Spring Road, from Cumberland Drive to Cobb Parkway. The portion, less than half-a-mile, of the project is expected to take up to a week.

The company said it is working with Cobb and Smyrna police departments on traffic control plans. The transmission line project is expected to be completed by mid-December.

The transmission poles installation is part of Georgia Power's Plant McDonough Project, which replaces 540 megawatts of coal-fired generation with more than 2,500 megawatts of natural gas-fired generation. According to Georgia Power, it will greatly improve air quality.

Construction of the natural gas combined cycle units is on schedule, Sell said, the first two units will come online in the first six months of 2011.

In order to get the natural gas to Plant McDonough, Georgia Power is building a 19-mile natural gas pipeline from Union City to the plant off South Cobb Drive in Smyrna. Construction is scheduled to be completed by March.

Georgia Power is adding a new 230-kilovolt transmission line and upgrading the transmission system in order to handle the increased amount of electricity being generated at Plant McDonough, enough to supply 625,000 homes.

The new line runs from Plant McDonough to the existing Smyrna substation located on Windy Hill Road. The route follows mostly existing right-of-way. The exception is a stretch along Cobb Parkway, which was chosen in order to avoid impacting about 50 residential properties, according to the company.

"The right-of-way got very narrow," Sell said. "We were going to impact about 50 residential properties if we tried to widen that right-of-way to put these big poles in. We thought it made a lot more since to come onto a commercial-industrial area, like the parkway, for that stretch instead of impacting those homeowners."

The entire project will cost $1.5 billion, Sell said.