Every construction project has its challenges, but some truly push the boundaries of what is achievable in the heavy civil industry. When the Indiana Department of Transportation sought to modernize its I-65/I-70 North Split Interchange in Indianapolis, Indiana, its request for proposals included building 47 new bridges and rehabilitating six additional bridges on an ambitious two-year timeline—905 days to substantial completion.

“Three design-build teams responded to the RFQ, and the same three teams responded to the RFP,” according to INDOT Strategic Communications Director Natalie Garrett. “Proposals were scored and evaluated using the best-value evaluation process defined by INDOT. The score was a combination of a technical proposal score and a price score.”

Ultimately, INDOT selected the Superior Construction/Janssen & Spaans Engineering Inc. design-build team to reconfigure and reconstruct the interchange. Their decision was made public in early 2020, just as the COVID-19 pandemic emerged.

Pandemic-related labor and materials shortages compounded the challenges associated with the project’s aggressive schedule and scope. However, the design-build team devised unique strategies, including resequencing the project and utilizing alternative concrete mixes, to deliver a modern facility poised to boost the area’s economic development and increase safety.

REVAMPING AN ANTIQUATED DESIGN

First constructed in the 1970s, the North Split Interchange has been a workhorse of the Indianapolis transportation infrastructure for decades. However, as the metropolitan area's population rose, the aging infrastructure's limitations became glaringly evident.

According to INDOT records, the interchange’s original design included frequent merges, weaves and lane changes over short distances, which led to many crashes, including more than 1,600 recorded crashes from 2012 to 2016 alone. 

INDOT identified the need for wider shoulders, intelligent traffic lights, dynamic signage, improved lighting and updated barrier systems to mitigate accidents and improve safety. The spatial limitations around the work zone also necessitated adding precautions to keep crews safe as they worked on these changes.

The North Split is the state’s second-busiest interchange, serving about 214,000 vehicles daily. Due to its high volume, another of INDOT’s top priorities was to minimize the impact of construction on travel times. To improve the movement of traffic during construction, Superior and JSE developed a design and traffic pattern that kept the high-volume interstate’s main artery—65 southbound to 70 eastbound; 70 westbound to 65 northbound—open throughout the project while enhancing safety for drivers and craft workers.

Superior partnered with Australia-based Propeller Aero during preconstruction to complete 3D drone mapping. They placed AeroPoints throughout the construction site to triangulate reference points for more than 170 scheduled drone flights. The high-resolution images taken during these flights were used to prepare 3D maps of the site, allowing them to confirm the placement of drainage structures, monitor traffic, including lane management during construction, and make real-time planning decisions involving maintenance of traffic and design.

The team analyzed the data compiled through the drone flights and devised a solution to build 32% of the project’s new permanent structures offline without affecting existing traffic patterns. Additionally, implementing unique construction sequences allowed offline construction in the interchange to be separated from the critical path, enabling the team to complete much of the work without affecting the existing traffic configurations.

OVERCOMING AN UNFORESEEN OBSTACLE

Superior’s crews broke ground on the project in February 2021 and hit the substantial completion milestone in May 2023. INDOT greatly emphasized the project timeline during the procurement process, but the COVID-19 pandemic complicated matters.

“One unique evaluation criterion for North Split was scoring the overall project duration [calendar days] and of specific movement closure durations [calendar days],” said Garrett.

To meet INDOT’s accelerated schedule demands, Superior brought in additional resources, collaborating with over 54 partners and signing 49 vendor contracts. Although the infrastructure contractor self-performed the project’s bridgework, they collaborated with subcontractors on various elements, including the bridge deck overlays and paving.

During the peak of the project’s labor demands, Superior employed more than 300 craft workers and more than 300 subcontracted craft workers.

“One person would test positive for COVID, and crews would need to adapt to working without their teammate,” said Doug Nichele, Superior’s Midwest Vice President of Operations. “Task hazard analysis was often performed more than once a day to make sure anyone stepping into a new role was aware of the safety risks and knew how to mitigate them.”

As with many construction projects at the time, the pandemic also fueled supply-chain issues. To combat material shortages, the design-build team resequenced work to offset delays. While waiting on mechanically stabilized earth-wall reinforcement materials, the team built many of the abutments onshore towers. Pouring abutments and setting bridge girders before MSE walls and embankment were completed allowed them to compensate for lost time.

Another time-saving strategy Superior employed was adapting construction practices to work through Indiana’s harsh winters. They prepped the subgrade to ensure water in the soil did not freeze and disrupt construction. Minimizing the temperature differential between the concrete mix and the surrounding ambient air helps preserve its long-term integrity; therefore, crews monitored the mix temperature at all stages: at the plants, while in the mixing trucks, and until it was finally cured on site. They used temporary heating and insulation blankets, localized tenting and ground-thaw heaters to protect it from the extreme cold.

When shoring the abutments, crews tented the scaffolding, pier, piling and formwork from top to bottom and preheated the structure to avoid creating cold spots that would compromise the concrete’s integrity. Superior also used a high-early concrete and tweaked the concrete mixes to accommodate the freezing temperatures. Reducing fillers enabled the mix to warm up faster, accelerating its strength gain. This expedited the project’s timeline by reducing the time the concrete spent under heaters, allowing crews to move on to the next task.

The North Split project team performed more than one million cubic yards of earthwork, removed and repaved 35 lane miles of new, continually reinforced concrete pavement and utilized over 150 pieces of major heavy equipment. Ultimately, the team constructed 47 new bridges, widened three existing ones and rehabilitated another three.

DELIVERING SUPERIOR RESULTS

The North Split Interchange Reconstruction, Superior’s largest transportation project to date, transformed the blueprint of Indianapolis. INDOT began a phased reopening of the interchange in December 2022, with the mainline portion opening to motorists on May 26, 2023.

Superior’s $399.5-million project modernized the North Split’s original design, resulting in a safer, more efficient traffic flow, easing congestion and reducing travel times for tens of thousands of daily commuters and freight operators.

Upon opening the final ramp, the focus of the remaining work shifted to aesthetic improvements, including painting, landscaping and lighting. The team will also add bridge monuments, resurface local streets and sidewalks, and construct sound walls at the northeast corner of the interchange. That work is expected to be completed by the end of 2023.