Crews are Digging 70-Foot Holes Along the Future CTA Belmont Bypass in Lakeview. Here’s Why

One of the many obstacles faced to date on the Red-Purple Line Modernization Projects is avoiding underground utilities that are almost a century old.

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The crews creating the soaring overhead structure that will untangle the Red, Purple and Brown line tracks north of Belmont are digging deep — 70 feet.

Construction workers are currently excavating 70-foot-deep shafts for the foundation for the Belmont Bypass, a key part of the CTA’s $2.1 billion Red-Purple Line Modernization Project.

Construction on the bypass is now in its third month. It’s the most ambitious public transportation construction project in the city’s history, playing out in one of Chicago’s most densely populated neighborhoods.

One of the many obstacles faced to date is avoiding underground utilities that are almost a century old amid the excavation.

Despite these challenges, construction of the towering “flyover” bypass which will carry Brown Line trains over Red and Purple line tracks north of the Belmont “L” station has been on schedule.

“We’re on a fast-paced timeline,” said Sven Bosold, the construction manager for the project. “But we should be able to finish [construction of
the bypass] by the end of next year.”

The Red-Purple Bypass bridge tracks will be a quarter-mile long and rise around 45 feet between School and Clark streets.

The bridge will be supported by steel columns, which crews are preparing for by digging 70-foot deep holes with eight-foot diameters. Nineteen of
these shafts will be excavated by the spring of this year, officials said.

Already, 16 Lakeview buildings have been demolished to make way for the construction.

Bosold recently toured the construction site for the bypass with Block Club Chicago. The construction sites are now in two different locations — on Roscoe Street between Sheffield Avenue and Clark Street; and on Sheffield Avenue between Roscoe and Clark.

CTA Red-Purple Bypass Bridge construction manager Sven Bosold directs crews while he stands before a group of “micro-piles” used during construction of the bypass on Dec. 17, 2019 in Chicago’s Lakeview neighborhood.

“Temporary casings are now being used to protect the drill shafts,” Bosold said. “Then, we’ll pour concrete into the holes, then erect steel beams within the hole.”

By late spring or early summer, workers will launch construction of the steel beams and concrete deck for the flyover, which will take around a year. After that, crews will complete rail, signal and tie-in installations for the flyover, with plans to have the connector track operating by the end of 2021.

One of the 70-foot holes excavated for the Red-Purprle Bypass bridge in Chicago’s Lakeview neighborhood on Dec. 17, 2019.

Bosold, who works for Walsh-Fluor, the CTA’s contractor on the Red-Purple Bypass bridge project, was also the construction manager for the $203 million CTA Wilson Avenue “L” rehabilitation project, which was completed in early 2018. He said the two projects share complications.

“In both cases, we were working in an urban environment, dealing with street closures and ongoing ‘L’ traffic,” Bosold said. “We have to make sure that our construction has limited impact to the community.”

The CTA and the city have had rolling closures in alleys adjacent to the construction work since the work began in September and will continue to do so throughout next year. Residents who haven’t been able to access their garages have been given alternate parking in a lot on the 900 block of West Newport Avenue during the construction.

The contractor for the bypass project has limited work to between 9 a.m. and 3 p.m. during the week to limit noise and disruptions to neighbors.

“We’re also utilizing equipment with noise reduction mufflers,” Bosold said. “And we’re installing noise projection walls if needed.”

Bosold said it takes up to three days to drill the individual holes, set the rebar and pour concrete down the shafts that have been excavated. The CTA and Walsh-Fluor are working with the city before project to relocate underground gas and electrical utilities that are located within the construction parameters.

Workers with the Walsh-Fluor construction company install temporary casings in a 70-foot hole which will eventually house one of the columns for the Red Line “flyover” on Dec. 17, 2019.

The city has also instituted a pest abatement program to eliminate the inevitable rodents that will be unearthed by the construction, although this hasn’t been an issue so far.

“We haven’t seen any major problems with rodents,” Bosold said.

The bypass bridge will allow the CTA to increase train speeds and allow more trains to run during rush hour because it will replace a 112-year old rail junction just north of the Belmont “L” stop. Right now, Red and Purple Line trains have to stop at the junction to allow Brown Line trains to proceed on their tracks, which go northwest.

After the bypass bridge is completed, the next stage of the project will involve straightening a curve which slows down “L” traffic on the Red Line tracks between Newport and Cornelia Avenues. The agency plans to demolish and rebuild about a third of a mile of the century-old structure during this stage of the project, which will take around three years to complete.

As part of this reconstruction, the contractor will move the century-old Vautravers Building at 947 W. Newport Ave. about 35 feet to the west to a space now used for parking in early 2021.

“We are building a completely new basement just west of the [Vautravers building],” Bosold said. “Then we will lift the building and shift it to the west.”

The Vautravers Building at 947 W. Newport Ave. will be moved to the parking lot next door to save it.

The other main phase of the Red-Purple Line Modernization Project involves the complete reconstruction of the Lawrence, Argyle, Berwyn and Bryn Mawr “L” stations on the Red Line to make these stations wheelchair accessible. Temporary rail stations will be constructed at Argyle and Bryn Mawr to serve customers while these stations are closed for reconstruction.

Work on these “L” stations will begin later this year.

Bosold said he’s never worked on a project with such a quick turnaround.

“We set shovels into the ground seven months after the project got awarded, which is unheard of,” he said.

Sven Bosold, the construction manager for the Red-Purple Bypass bridge, stands in front of workers installing a temporary casing for one ot the bridge’s column on Dec. 17, 2019 in Chicago’s Lakeview neighborhood.
CTA Red-Purple Bypass Bridge construction manager Sven Bosold holds a piece of clay excavated during construction of the bypass on Dec. 17, 2019 in Chicago’s Lakeview neighborhood.

For general project information, Lakeview residents can email the CTA at Visit the CTA’s website at for the construction activity notices or call CTA Customer Service at (888) YOUR-CTA.