One would have to be blind not to notice all of the construction activity along the 30-mile stretch of Interstate 35E between US 380 Highway in Denton County and I-635 in Dallas. Orange construction safety barrels and cranes delineate the $1.4 billion 35Express project area, as do the abundance of trucks hauling materials to and fro and excavators carving out embankments. Copperas Branch Park has been transformed from a peaceful recreation area on the shores of Lewisville Lake into a materials laydown yard for the duration of the project, but the promise of increased capacity and improved mobility and safety on one of the most congested interstates in Texas makes it worth the temporary sacrifice by local citizens.

North Texas commuters have firsthand knowledge of the staggering amount of time and money Texans are spending in traffic these days. With estimates indicating that the state's population will grow an additional 18 million by 2040, the problem will only get worse.

The 35Express project is one of several, behemoth transportation improvement projects that the Texas Department of Transportation (TxDOT) currently has under construction. 

The $1.4 billion 35Express project underway in Denton and Dallas Counties is the first of two phases of improvements identified by TxDOT. Funding has not yet been secured for the remaining, $3.4 billion phase.

The 35Express project will improve 30 miles of the interstate corridor by adding: new interstate main lanes; an 18-mile reversible, managed toll lane system; direct connections and new interchanges; improvements to more than 75 bridges and four parks; a new southbound bridge across Lewisville Lake; and continuous frontage roads throughout the corridor.

The project is being tackled in three different segments: north- from U.S. Highway 380 to Swisher Road/FM2181; middle - Swisher Road/FM 2181 to President George Bush Turnpike; and south - President George Bush Turnpike to I-635.

AGL Constructors, a joint venture of Archer Western Contractors LLC, Granite Construction Inc., and The Lane Construction Corporation, broke ground on the first phase October 24, 2013 and will be placing the final beams for the new bridge over Lewisville Lake in early 2016.  Deck work on the bridge is ongoing, with plans to open the new bridge to traffic by mid-2016.

By the time the 35Express project is completed in 2017, the six-lane chokepoint over Lewisville Lake will have been transformed into 14 lanes. 

TxDOT and the project management team evaluated traffic counts, congestion modeling and anticipate future growth to determine the most effective configuration for the 35Express project, said Kimberly Sims, Project Spokeswoman. 

A key feature of the project is the 18-mile, reversible managed toll lane system at the southern end of the project that will replace the current HOV lane system and perform as a flexible, congestion management tool. 

Extending down the center of the interstate from I-635 in Dallas County, north to Turbeville/Hundley Road in Denton County, the managed lane system will flow southbound to the Dallas area during the morning rush hour and northbound during the afternoon commute home.

"Managed lanes provide drivers with a choice for a higher level of service and use a variable pricing approach, which means the price is anticipated to be higher during rush hour and lower when traffic is lighter," Sims explained.  "The system is automated and uses moveable gates protected by barriers to prevent opposing traffic from entering the lanes. Motorists can enter and exit the 35Express managed lanes at several locations."

Revenue generated from the 35Express managed lanes will go towards funding future improvements to the I-35E corridor. 

Another key element of the project is providing a direct connection between the 35Express managed lane system with the I-635 TEXpress managed lane system, Sims added. Direct connector ramps will be added to allow motorists to travel more easily between the I-635 and I-35E TEXpress managed lane systems.

Designing a Complex Intersection

The intersection over Belt Line Road in Carrollton is one of the most complex pieces of the entire project. With an average daily traffic count of 24,000 vehicles, the intersection is one of the busiest along the 30-mile corridor of I-35E. It is also currently a "spaghetti mix" of three or four railroad lines that crisscross the interstate in the heart of the city's downtown, resulting in a daily barrage of horn blowing and traffic jams, said Matthew Marchant, Mayor of Carrollton.

AGL Constructors revised TxDOT's original, preliminary designs that would have routed the currently at-grade Belt Line Road underground, beneath the existing rail lines. Instead, AGL, in partnership with the design team of Parsons and HDR Inc., proposed an alternative technical concept (ATC) to elevate Belt Line Road to roughly 35 feet above ground (the current height of I-35E) and to elevate I-35E above that, roughly 60 feet above ground. The frontage roads at the intersection will also be elevated 35 feet above existing ground level to tie into Belt Line Road.

"It will be a three-level intersection that will not only alleviate traffic congestion, but also improve the railroad crossing safety in that area," said Dan Horvath, AGL's Construction Manager for that portion of the project.

Poor soils and a high water table in the area would have made routing Belt Line Road beneath the rail lines a "massive undertaking," Horvath added. "It would also have added complications with finding a way to shore up the existing railroads while keeping them live."

The alternative concept to elevate Belt Line Road, the frontage roads and I-35E actually resulted in a cost reduction for the owner, Horvath said.

He added that the interchange is bustling with activity, with at least a dozen crews of workers and about eight cranes working now. 

Much of the new, elevated lanes are founded on drill shafts with cast in place substructure. Where there are long spans over the railroad lines or streets, the column caps are post-tensioned, Horvath said. "We are using both pre-stressed concrete girders and structural steel girders, and we use precast deck panels when we can." 

Three concrete plants and a fleet of 15 concrete mixer trucks feed about 1,000 cubic yards of concrete per day to the project.

"Access for equipment and materials is a challenge," Horvath said. "We are building in between the frontage road lanes and the existing interstate lanes, as well as Belt Line Road, so we are boxed in on all sides by live traffic. Then, of course, there are the railroads and overhead power lines to work around."

In order to maintain traffic flow on the existing frontage roads, I-35E and Belt Line Road, the contractor is performing many activities at night, including setting bridge beams and pouring concrete bridge decks.

"We are working a full-time night crew," Horvath said. "If you include our subcontractors, we have just shy of 200 people working on this segment alone."

However, the biggest challenges of the complicated project area at the interchange will be the 12 major traffic switches as vehicular traffic is transitioned from old structures onto the new lanes.

"We are approaching one of our major traffic switches to get existing interstate traffic onto the new, I-35E main lanes bridge," Horvath said.

Once the north and southbound traffic has been rerouted onto the new, main lanes bridge, AGL Constructors will begin demolition of the existing bridge and construction of the remaining new, main lane and frontage road bridges.

Boosted Economic Development in Carrollton 

Posterity may recognize 35Express as a pivotal turning point in Texas transportation projects that manage to go beyond merely moving vehicular traffic and contributing to economic development to actually improving connectivity, livability and quality of life for the communities it touches.

Local communities such as the City of Carrollton are embracing the project and taking advantage of the opportunity to coordinate other improvements that will improve the walkability of the city's downtown, enhance citizens' use of outdoor spaces, and simply make day-to-day life easier and more enjoyable.

"Since I-35E bisects our city, most residents use it a lot," Mayor Marchant said. "The 35Express project not only means improved mobility on a commercial corridor that is vital to the state and the nation, but it also means lower commute times for our local residents and businesses."

The AGL Constructors design alternative, devised in conjunction with Parsons and HDR, also provided the community with better access to its redeveloping downtown, said Cesar Molina, Engineering Director for the City of Carrollton.

"With Belt Line and the frontage roads being lowered, the downtown area would have been kind of an island," he explained. "It would have taken a longer route to get into local streets, and it would have required us to build bridges for pedestrian connections. With this plan, everyone can walk on the ground. It removed the traffic that would have been an impediment to people walking across the interstate to revitalized areas."

Carrollton's downtown revitalization began in 2009, with the arrival of the city's first Dallas Area Rapid Transit light rail line. The city embarked on some infrastructure upgrades, replaced some sub-standard, multi-family construction with the Union at Downtown Square, a public-private partnership, mixed-use development that features 300 apartment units and retail on the first floor, Molina explained. The third phase of that project is currently in the planning phase. 

The City of Carrollton was founded around the railroad lines that still run through it. Incorporated in 1913, the "heart" of the city is the Downtown Square, which has been a gathering point over the past 100 years, said Marchant, who grew up in a house that is only a block from the square.

It wasn't that the square or the downtown area was exactly in decline, but Marchant didn't feel like it was meeting its full potential. 

When he was sworn in as mayor in May of 2011, Marchant became the self-appointed champion of the square, advocating for more green space to make the square more inviting for public gatherings. 

 "We repainted the nearby grain tower, which is also a signature of downtown, with the city's logo, which you can see from I-35E," Marchant said. "And we worked to attract more restaurants to the downtown area."

Another key element to improving the downtown square was the refurbishment of the Carrollton Gazebo, which has been a local icon since it was originally built in the 1870s, Molina said.

In conjunction with the introduction of the DART line in 2009, the City of Carrollton began hosting its annual Festival at the Switchyard, which has grown into the city's largest annual event, said Kelli Lewis, the city's Marketing Director. "We had approximately 27,000 people out this year for the all-day festival that featured headliners 3 Doors Down and Fastball."

Special holiday activities and movie screenings are routinely held at the repurposed town square. 

"It has become the place to be," Molina said.

This past November, the Texas Downtown Association President's Awards Program named Carrollton's historic downtown revitalization winner of the 2015 Best Public Improvement project. Carrollton also won the public voting component of the contest, the People's Choice Award, which was determined by votes on Facebook. 

Key to repurposing the square was convincing surrounding businesses to give up about 140 parking spaces, Molina said. The only way that happened was to promise those parking spaces would be replaced, and potentially several hundred more added, with the new parking lot that will be constructed at the I-35E/Belt Line Road interchange.

"In the fall of 2017, when AGL Constructors is finished, the City will bring in our own contractor to put in those 140 parking spaces, and we'll have the ability to add up to 600 spaces total," Molina said.

The 35Express project provided the perfect opportunity for Carrollton to dovetail some of its own betterments/quality of life improvements and feed off of the momentum of the bigger project, Molina explained. Some area bridges have been dressed up with a more decorative railing and lighting, and those elements will be carried over to the new parking lot. The embankment retaining walls along the I-35E corridor through Carrollton will feature the city's signature gazebo.

 "The proof's in how it's all come out, the revitalization," Molina said.