Very soon now, “Road Work Ahead” signs will start appearing on Alcoa Highway. They will probably be there for at least a decade as work proceeds in four stages extending from the Buck Karnes Bridge over the Tennessee River to McGhee Tyson Airport. All in, projected costs approaching $300 million make this the most expensive highway construction project ever in the Knoxville area. Alcoa Highway will be transformed into a six-lane expressway with limited access—entrance and exit ramps and flyovers will eliminate left turns onto the roadway.

The first stage, which is getting underway this spring, covers the 1.67-mile stretch between Woodson Drive and Maloney Road. Just in that short span, three new bridges will go up over the highway and more than 5 miles of ramps and frontage roads will get built, with massive amounts of excavation and landfill needed to support the widening of the existing four-lane roadway.

What’s most remarkable to me is that TDOT claims all of this can be accomplished while keeping two lanes open in both directions at all times and without ever restricting access from residential side streets and commercial strips.

For all its safety issues, Alcoa Highway has been a great vehicle mover with a 47,000 daily traffic count that’s the highest of any non-interstate highway in Knoxville. But as a rock slide that closed one lane for weeks in 2013 evidenced, a reduction in its capacity spells gridlock.

So how is that to be avoided when the highway becomes a huge construction zone? TDOT’s regional coordinator, Kristin Qualls, patiently talks me through the staging of the project as we peer at a 15-foot-long rendering of what the vicinity will look like upon its completion.

One of the first stages, and most challenging, is construction of the three bridges over Alcoa Highway that will enable both north- and south-bound traffic to traverse it without making a left turn. (Left turns across traffic are the most perilous part of driving on Alcoa now.) One of the bridges will be at Maloney Road on the south end, one at Montlake Drive near the north end, and one in between. Since I happen to live on Maloney, but mostly access Alcoa on Montlake, I can relate to this better than I may able to convey it.

The hardest part of getting the bridges built without impeding traffic is erecting the steel and concrete piers in the median of the roadway to support the bridge deck that will be mounted on abutments on either side. It may take as long as six months to build the pylons, and while workmen are doing so, their protection requires cordoning off the center lanes with barrier rails. Thus, widening the highway in the vicinity of the bridges is a prerequisite in order to preserve two lanes in each direction. And a prerequisite to that widening is clearing the area, which has dense foliage in places, and leveling the terrain in places that are steeply sloped. So that’s where it all starts.

Once the abutments and pylons are in place, the bridge decks will be installed by stretching beams across them with steel rebars holding the poured concrete in place.

It’s hard to imagine how all of this can be going on overhead while Alcoa Highway traffic continues to move unabated, but Qualls insists it can.

Completion of the bridges is only one of several prerequisites to proceeding with the rest of the widening of the roadway between Woodson and Maloney. Before that can happen, ramps to and from the bridges will have to be erected, and all present means of accessing the highway will have to be replaced. In addition to the ramps, several miles of new frontage roads will provide a glidepath for convergence with the highway from both the bridge ramps and existing side street entrance and exit points.

In my own case, accessing Alcoa from Montlake to its west will mean either taking the bridge across to a northbound connector road, or taking a mile-long frontage road that feeds into southbound Alcoa. And carving the path of this frontage road through steeply sloped terrain on the west side of the highway represents an engineering feat in its own right. A mammoth 53-foot-high retainer wall will be drilled into the hillside above it and an elaborate network of pipes will be installed for drainage along the bed of an existing creek.

Only after all new connections are in place can existing side-street access/egress points be closed in order for most of the highway widening to begin. Once again, barrier rails will be placed on the edge of the existing roadway to shield construction on either side.

Three years and $67 million down the road, Knoxville should have its closest thing to an Interstate highway that isn’t one. By then, work is due to have commenced on the second phase of the Alcoa project, covering the stretch from Maloney Road south to the Little River. Now that Congress has broken a logjam in federal highway funding with the enactment of a five-year, $300-billion measure, prospects have brightened for the continuation of projects like Alcoa, which are 80 percent federally funded.

As much as I have long recognized the need to redress the hazards and hassles of driving Alcoa Highway, I’ve also been concerned that having to drive through a construction zone could make matters worse for several years. So I’m guardedly encouraged by TDOT’s assurances that all the roadwork can get done without disrupting traffic.

Joe Sullivan

Joe Sullivan is the former owner and publisher of Metro Pulse (1992-2003) as well as a longtime columnist covering local politics, education, development, business, and tennis. His new column, Perspectives, covers much of the same terrain.