Chicago Transit Authority’s (CTA) Subway

“As a result of this initiative, the CTA is poised to host the most comprehensive 4G LTE enabled subway network… advanced broadband connectivity and communications are imperative for today’s modern city.” – CTO of the Chicago Transit Authority


Quick Stats:

  • More than 832,000 riders daily and 243.5 million riders annually (as of 2022)
  • Nine weekends of installation work
  • 25 cars on the custom-built construction train
  • 50-75 engineers, network technicians and safety personnel in total on board the train to install 4G equipment
  • 22 miles of tunnels and 21 underground train stations received 4G service


The Challenge:

In 2015, the city of Chicago became one of the first U.S. cities to prepare for the onset of “smart cities” and invest in public wireless connectivity. Noticing the lack of cell phone signal on the underground red and blue lines, the Chicago Transit Authority (CTA) quickly identified 4G service on public transit as a priority for Chicago.

The challenge was to install 4G wireless service along the red and blue lines to propel Chicago towards a smart city status, all without interrupting the flow and operations of the daily riders who depend on the CTA trains for their commute. By ensuring seamless connectivity along public transit lines, the city wanted to increase ridership by offering better amenities. They hoped that once people could use their devices to work or wind down during their commute, customer satisfaction would increase and people would be more likely to choose the CTA.


The Unique Solution:

The CTA and City of Chicago brought in Extenet, Aldridge Electric and the four major wireless carriers to install 4G infrastructure along the city’s underground train tracks. Over the course of several weekends in 2015, Extenet and Aldridge Electric used a custom-built 25-car train with 50-75 engineers, network technicians and safety personnel on board to install radios and fiber optic cabling throughout the CTA’s red and blue lines.


Keys to Success:

  • Throughout the nine weekends it took to deploy the equipment, no tunnels or trains were ever shut down or canceled due to the installation. The tunnel construction train was a rolling platform – as it moved along each tunnel for the team to install equipment, the CTA routed trains into the opposite tunnel around the installation team. Extenet partnered closely with the CTA to coordinate project execution within the operations of a mass transit train system.
  • All four major wireless carriers and the city of Chicago set profit aside to focus on improving customer experience. Projects like this often fail because nobody wants to foot the bill without a guarantee of future profit. However, AT&T, Verizon, Sprint, T-Mobile and the Chicago administration recognized the value of customer satisfaction and retention – phone customers are less likely to switch to another carrier if they are happy with their current connectivity. Similarly, more people will take the CTA if they know they’ll be able to continue working or unwind with their favorite TV show on the train.



This project brought 4G service to 22 miles of tunnels and 21 underground stations. The connectivity along public transit lines allowed people to work from the trains, providing better amenities to more than 832,000 people daily. This project with the CTA shows that oversight and buy-in from all stakeholders is key to project success – Extenet coordinated with multiple stakeholders to get all four wireless carriers on board, reduce costs and timeframes, and execute an installation that prioritized the people of Chicago. It was an example of Extenet leading at the vanguard of wireless innovation.

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