The Council Bluffs Interstate System (CBIS) needed an overhaul.
It was constructed as part of the Eisenhower Interstate System in the 1960s and, apart from routine maintenance, has remained virtually unchanged since. Packed with traffic and frequent crashes, the Iowa corridor no longer met current design standards, guidelines, or operational criteria. It also lacked operational capacity and could not accommodate expected growth.
Enter the $1.5 billion CBIS Improvement Program: a 14-mile interstate modernization project that will accommodate development, reduce congestion, improve mobility, and increase traveler safety. CBIS includes the state’s most innovative transportation solutions and the area’s first dual, divided freeway. It is Iowa’s first construction project to use tiered environmental permitting and robust critical path method (CPM) scheduling. It also is the Iowa DOT’s first project using a program manager.
Implementing the project was a feat of engineering. Efforts included relocating multiple Class I railroads, overcoming worldwide pandemic implications, managing through multiple flood events, designing complex bridge structures, traversing multiple waterways, moving an astronomical quantity of material, and maintaining traffic on one of America’s most vital corridors.
These efforts were completed on budget and ahead of schedule. This project provides a blueprint for large-scale interstate rehabilitation and overhaul efforts in a dense urban corridor, requiring coordination with dozens of agencies, and ongoing communication with the traveling public.
Mark Pohlmann, the program manager at HDR who oversaw the project, said railroad relocation was the biggest challenge. One of the Midwest’s “railroad gateways,” a fourth of all trains crossing the country pass through Council Bluffs. Five Class I railroads have nine main lines that converge at Council Bluffs, each feeding into two regional classification yards.
Long impacting local traffic around Council Bluffs, the Iowa DOT and City of Council Bluffs sought the CBIS Program as an opportunity to consolidate, streamline, and reduce the impacts of the railroad lines. Coordinating with BNSF, Iowa Interstate Railroad and CBEC Railway, the HDR team performed a railroad traffic and operations analysis to consolidate four main lines approaching from the south and east into a common corridor and eliminate nine at-grade crossings.
Crossing under the dual divided highway, this effort improved rail operations while reducing traffic congestion, provided future capacity for the railroads, and eliminated switching across streets.
The relocation was critical to the interstate reconstruction design and construction phasing, according to Pohlmann.
“Construction had to be accomplished via three separate construction contracts, which were administered simultaneously,” Pohlmann said. “Right-of-way transfers were executed in phases as construction progressed, strategically transferring ownership rights between the City of Council Bluffs, BNSF, Iowa Interstate Railroad, and the Iowa DOT. And cutovers of rail trackage had to be scheduled and executed in short track outage windows so as not to interrupt critical freight movements.”
With bridges and pier locations spanning the rail lines, the team’s diligence minimized the impacts to rail and intermodal operations. They reorganized a contract to construct the piers located in the rail yard for the freeway’s eastbound structure at the same time as the westbound structure, so rail operations would be interrupted just once, saving time, money, and minimizing future impacts.
The constrained site also influenced the highway design. Bridge span arrangements and constructability around the rail lines not only considered the current track locations, but those proposed. Further, to improve access in the future, the team incorporated inspection catwalks and access safety cables as part of the bridge designs.
The extensive network of catwalks and safety cables allows unimpeded access to the underside of the bridges for mandated maintenance inspections while continuing railroad operations without interruption.
In addition to modernizing the interstate to today’s standards, the dual, divided freeway and CBIS Program overall provides innovative, long-term system updates.