CDOT Twin Tunnels Expansion Project Breaks New Ground with Construction Man

By Vivian Engen, Process Improvement & Change Management Intern

September 20, 2018

Every year, millions of travelers pass through the Veterans Memorial Tunnels (previously known as the Twin Tunnels) on a short stretch of the Interstate-70 corridor in Colorado. What most of the traveling public doesn’t know about the Tunnels is that the third lane on the eastbound side is the product of a groundbreaking project delivery initiative called Construction Manager General Contractor, a recent trend in roadway construction project delivery. 

The Colorado Department of Transportation (CDOT) Twin Tunnels Expansion Project was designed to add additional vehicular capacity along the I-70 corridor. Completed in summer 2014, the project added an eastbound lane and provides for future westbound capacity and other improvements. However, as recently as 2010, CDOT secured funding and support from the Transportation Commission and Governor Hickenlooper, but had yet to select a project delivery method to meet the two-year project deadline and limited budget. 

I-70 tunnels

I70 Twin Tunnels

The project team settled on Construction Manager General Contractor (CMGC) as the best-fit approach to overcome the tight turnaround and budget constraints. “The right construction approach required the ability to accelerate construction phases and spend money immediately,” said Ben Acimovic, a Professional Engineer at CDOT and the Twin Tunnel Project Manager. “CMGC provided a framework that required the project team to work together to meet tight deadlines and agree on Project-First solutions,” he continued. “The method was a great fit for the project, as well as the larger-scale team-based development spirit at CDOT.” 

CDOT’s use of CMGC to deliver a tunnel expansion construction project was the first of its kind in the state. The high-risk nature of tunnel construction was the key factor that made CMGC the right delivery method for the project. “Tunnel construction demands intensive labor in high-risk, sometimes dangerous, work conditions,” explained Acimovic. “Anything that is high-risk can be interpreted to determine how to proceed considering the constraints.” 

What is CMGC?

Based on agile—a project management process that breaks project tasks into smaller two-week sprints —CMGC follows a similar route by breaking down the complex structure of a construction project into pieces that are iterated, then reassembled to improve project deliverables. 

“Agile-based methodologies are typically used in software development, where processes are inherently iterative,” Acimovic explained. Civil engineering, however, is typically understood as a linear process where decisions are made quickly and autonomously. Despite the distinction in tunnel construction and software development, the project constraints imposed on the Twin Tunnels project pushed CDOT and Acimovic to consider different alternatives to a typical construction plan. 

CMGC builds on agile principles through a methodology founded on project flexibility, control over design decisions, and speed. These outcomes are a partial product of the emphasis CMGC places on forming a strong partnership between CDOT, the contractor and the design consultant in the early project stages. With everyone on the same page prior to breaking ground in the construction phase, the strong partnership fosters a team atmosphere that propagates positive consequences, such as mitigated project risk, an improved construction schedule, and finishing under budget. 

How is CMGC different from linear project management?

“CMGC demands an approach to construction that is contrary to the way most people have done construction their entire careers,” Acimovic explains. For example, as with most construction projects at CDOT, a combined team of CDOT engineers and outside consultants and contractors collaborated to complete the job. For the Tunnels project, the team made important decisions collaboratively. For example, “very conservative tunnel engineers [were] advocating for smaller blast lengths, whereas the contractors took a more aggressive approach and wanted to go with bigger blast lengths,” explained Acimovic. 

The team engaged in collaborative CMGC discussions for a whole week to iterate the contrasting opinions between the design engineers and contractors on risk tolerance and the capability of the rock. “We reached a consensus where we used three different blast lengths for three different types of rock,” said Acimovic, “we applied this blasting technique throughout the entire length of the tunnel and saw a lot of success.” 

How did CMGC lead to better project outcomes?

The Twin Tunnels Expansion project finished on schedule and $3.5 million under the final contract budget. “We wouldn’t have been so successful without the iterations that prompted in-depth discussions and control over decisions on the tunnel design between all members of the project team,” Acimovic explained. This is just one example where CMGC resulted in tremendous success for this project. 

This success brought statewide and national attention. The CDOT Twin Tunnels Expansion Project was awarded Best Highway/Bridge Project for the 2016 Engineering News-Records Mountain States Best Project competition, and received a national environmental award from E&R. 

CMGC is becoming a more widespread practice at CDOT. John Hall, a CDOT Design Engineer who applied CMGC on the Interstate-25 (I-25) South Gap and I-25 Arapahoe roadway construction projects highlights the “reliable ability to estimate time and cost of a project with the contractor at the table” as well as how best to phase the project. “Road construction is different [than vertical construction] in the sense that we have to keep all the people who are using the road in mind when building a construction plan,” he explained. “Delivering reliable outcomes, coming in at [or under] budget and deadlines becomes much more feasible with the contractor as part of the team from the start project.” 

The joint funded Interstate-70 (I-70) Eagle Interchange, Vail Underpass, and Edwards Interchange projects also used this delivery method, specifically to overcome difficult traffic control limitations on busy mountain town interchanges. “The early contractor engagement provided by CMGC allowed us to approach the public with confidence in the schedule to get input about stakeholder preference between a high-impact, shorter project timeline, or a lower-impact, longer project schedule,” explained Matt Figg, the Project Engineer. “CMGC fostered a much more collaborative and engaged process not just for the project team, but also with the local community because the contractor was at the table to eliminate uncertainty.” Other CDOT roadway construction projects that have applied, or are in the process of using, CMGC include I-70/Pecos, Rocky Ford Bridges, Dotsero Bridge, Grand Avenue Bridge, and the Eastbound I-70 Peak Period Shoulder Lane.  

Acimovic expects that application of CMGC on future roadway construction projects will only become more popular. “Today’s transportation infrastructure is being built to incorporate technology,” said Acimovic. “Rechargeable roads, vehicles that talk to each other and the surrounding infrastructure, as well as technological and big data solutions incorporated into the roadway will only make CMGC a more attractive roadway construction option for future CDOT projects.”