ARLINGTON -- Motorists approaching the downtown Dallas area from the west and south will have to deal with a massive amount of road construction over the next four years.But when the work is done, the Interstate 30-Interstate 35E corridor will be one of the widest roadways in the region - spanning 23 lanes.The Texas Transportation Commission on Thursday selected a firm known as Pegasus Link Constructors to design and rebuild the I-30/I-35E corridor on the west and south ends of downtown Dallas. The area has long been considered one of the worst bottlenecks in the southwestern United States.Pegasus Link Constructors is a consortium of companies led by Fluor Enterprises Inc. and Balfour Beatty Infrastructure Inc. Pegasus bid a total of $798 million to take over the project. The companies also will maintain the highways for the first 15 years after the work is done."Construction should take four years - 1,510 days," said Russell Zapalac, Texas Department of Transportation chief planning and project officer. He said construction was scheduled to being next year.Money for the project comes from at least seven pots of state funds, including traditional tax-supported funds, dollars from bond debt and some revenue generated by toll roads in the North Texas region.The project has become known as the Horseshoe, named after the shape that Interstate 30 and I-35E take as they merge and bend around the west and south sides of downtown Dallas. And soon, it will become a gigantic, horseshoe-shaped work zone.