At Denver International Airport (DEN), the intra-airport train system is critical for operations. Passengers can walk from the Jeppesen Terminal to Concourse A, but the only way to get to concourses B and C is via train. Lately, many have been riding in brand new cars with more comfort features and technology. The airport began rotating new cars into service last summer, and 13 of 31 had been replaced as of January. An additional 13 are scheduled in 2025, bringing the new total to 41.
When DEN opened in 1995, the airport’s Automated Guideway Transit System (AGTS) people mover had 16 cars split into sections of four each. By 1996, the airport had added six more cars, and then another nine from 2001 to 2007. By 2021, the company that built the train cars had been sold twice: Bombardier Transportation bought out AEG Westinghouse in 2001, and Alstom purchased the transportation division of Bombardier in 2021.
As DEN’s trains racked up miles, the airport developed a plan to replace aging cars. The recently installed cars from Alstom are a big step up from that inaugural set.
 facts&figures
Project: Replacing Cars in Airport Train Location: Denver Int’l Airport Program Cost: $78.85 million (each car costs Funding: 100% self-funded as part of airport’s Timeline: Cars ordered in 2018; initial delivery in Number of Train Cars: 26 new cars, bringing total to 41 Car Manufacturer: Alstom Construction Manager at Risk: Xcel Energy Lead Consultant: Logplan Key Benefits: Better reliability; enhanced passenger comfort |
As the third busiest airport in the U.S. and sixth busiest in the world, DEN accommodates an average of 200,000 passengers every day. To compare, Hartsfield-Jackson Atlanta International (ATL) sees 286,000 passengers per day, and both airports rely extensively on train systems. They even use the same type of cars and signaling systems from Alstom.
“Atlanta’s airport has a system that is very similar to ours; it’s almost identical,” says Matthew Robb, senior vice president of Technical Operations at DEN. “The difference is that with our system, we have switches that enable us to run upwards of 40 unique operational modes, which helps us while we’re troubleshooting an issue or conducting overnight maintenance. And, of course, the Atlanta airport has a walking tunnel that enables access to all seven concourses.”
Improving the Passenger Experience
The first train cars at DEN were CX100s from AEG Westinghouse. After more than two decades of service, they began showing some wear and tear. The oldest, after all, had logged more than 1.6 million miles. Robb reports that reliability was still surprisingly good, but it was starting to take a hit. For example, the couplers that connect the train cars were becoming problematic, causing ghost codes that cost crews time and energy to investigate. On top of that, it was becoming more difficult to source replacement components.
Along the way, the maintenance team performed routine inspections and minor service on every car every other day. And just as automobile drivers do every 5,000 miles or so, DEN sent its train cars to the shop every 7,000 miles for routine preventative maintenance. Over time, however, the interval between significant repairs began shrinking, a telltale indication of wear.
“While the CX100s were starting to show their age, I really can’t say enough about the Alstom operations and maintenance team here in Denver, because they’ve done an outstanding job of keeping those things running,” Robb says. “Historically—even last year—our availability was well north of 99.7%, which other airports would love to have. We’re happy to see these new cars come in and provide us even more reliability. And the CX100s, thanks to our maintenance team, have continued to perform fairly well.”
With its new set of cars, DEN is the first airport in the United States to operate Alstom’s replacement model, the 300R. Boasting that new car smell and enhanced customer features, the 300R has LED lighting and new dynamic screens inside that allow the airport to post information and marketing messages more effectively. In the older cars, personnel have to switch out paper signage. More important is an upgraded heating, ventilation and air conditioning (HVAC) system that significantly improves passenger comfort.
“The cooling, specifically, is a huge improvement over what we saw in our CX100 vehicles,” Robb reports. “In fact, that’s one of the biggest complaints we’ve heard from our customers about the CX100s. As these cars age and the HVAC systems became less and less effective, the vehicles would run exceptionally hot, especially in the middle of a summer day when you’re on the train with 40 or 50 of your closest friends. It just wasn’t a great experience.”
Beyond the upgraded HVAC system, Robb reports that the overall ambiance inside the cars is much improved. When the airport partnered with United Airlines in December on its “fantasy flight” program for kids with special needs, system operators changed the lighting to holiday colors, much to the children’s delight.
Installation and Maintenance
Alstom staffs three maintenance shifts 24 hours a day, seven days a week at DEN. Project Manager Orisay Lameda, who originally started with Bombardier 30 years ago, actively participated in the planning and installation phases to help facilitate as the old cars were swapped out.
“Denver has a complex airport,” Lameda says. “It’s very busy and it’s hard to introduce a new car without impacting customer service. We worked with the airport to achieve seamless integration and had only two scheduled shutdowns as part of our normal testing procedure.”
For each replacement, Alstom ships the new car one week in advance via trailer truck. After the car’s four-day journey, it waits in a parking lot at DEN while its older counterpart is pulled from the people mover system and sent to the scrapyard for recycling. As part of the decommissioning process, the airport salvages all parts needed to support its fleet of CX100s still in operation. DEN has also taken the initiative to sell parts to other airports. Houston Airport System, for instance, has purchased two couplers for its own aging CX100 cars.
Meanwhile, the product production team starts the commissioning process for the new car with additional testing. On site, Alstom’s local maintenance team coordinates the installation, including a full inspection with the DEN Fire Department for certification. It’s that kind of attention to detail, along with a stringent maintenance agreement, that has resulted in long life for the previous generation of train cars, notes Robb.
“We entered a new operations and maintenance agreement with Alstom at the beginning of this year, and the minimum uptime requirement is 99.86%. That’s really setting the benchmark for the rest of the industry,” he remarks. “In other places, we see 99.5% and 99.7%; but because our system is a must-ride, we require that high amount of availability.”
If Alstom fails to meet the 99.86% threshold, it faces a financial penalty.
DEN took delivery of its 13th 300R train car this January, which means it’s about halfway through the changeover process. Three of its older CX100 vehicles have been decommissioned (coordinated by the local Alstom crews), and the project team is working at a “one out, one in” cadence. Currently, the airport is phasing out the first 16 CX100s that were purchased when the airport was built. It will keep 15 of the younger CX100s for now, but management is talking with Alstom about ordering additional 300Rs to replace them. Robb expects those cars to be delivered in 2028, and then all of the CX100s will be retired.
Before any of the new 300R cars are accepted, they undergo routine site inspections and testing followed by 300 hours of demonstration testing.
With this new set of cars, DEN can run eight trains consecutively, whereas previously it could only operate seven. That increases the system’s hourly capacity 13% to 15%, and decreases the time between trains accordingly. That translates into faster, more efficient service for passengers going to/from the concourses.
The heating and air conditioning system in the new cars is a significant upgrade or passengers.
Robb explains that the new cars are part of a living asset management strategy to replace assets that have reached, and sometimes exceeded, their useful life. It’s also one of several improvement projects the airport is completing as it prepares to reach the strategic objective of serving 100 million annual passengers.
Regenerating Energy
Electricity for the train is supplied by Xcel Energy, a regulated electric utility and natural gas delivery company based in Minneapolis that serves nearly 4 million electric customers and more than 2 million natural gas customers across eight states, including Colorado.
Xcel provides backup power for massive entities like the Denver Stock Show and Denver Rescue Mission, but honing the power for an airport people mover system is a first for the company. Through a program called Empower Resiliency, it will own, install, operate and maintain microgrid assets, including battery storage, renewable energy and backup generators.
“This project is important to us,” says Beth Chacon, director of Integration and System Performance at Xcel. “We wanted to do a demonstration of battery projects, and the community is interested in more resilience for these public facilities.”
The new train cars also support DEN’s long-term sustainability goals. Just like battery-electric vehicles, the train cars are equipped with regenerative braking. The new DEN battery system that provides backup power to the Automated Guideway Transit System is charged by one of DEN’s solar arrays. Separately, the new train cars have regenerative braking capabilities that allow the energy created by braking to flow back onto the track and offset the train system’s overall power usage.
“So far, we only have two trains running,” Lameda reports. “Once we have completed the process, we will be able to regenerate power for all of the cars.” That will be a win for riders, the airport and the environment.
