Ten years of the Flatiron Flyer: A decade of keeping the northwest metro connected

The circulatory system of the human body is the most important system of the body. The system is responsible for carrying blood cells, oxygen, nutrients, hormones, and other substances critical to keeping the rest of the body functioning through a network of arteries, arterioles, veins, venules, and capillaries. Much like how the circulatory system operates, cities function in the same way. Highways and interstates serve as the city’s arteries and veins, while collector and local streets serve as arterioles, venules, and capillaries. For the Denver metro area, one of those major arteries is the Denver-Boulder Turnpike, officially designated as US 36, home to RTD’s Flatiron Flyer (FF) service between downtown Denver or Aurora, and Boulder. On Saturday, it celebrates a monumental milestone: a decade of keeping Denver, Aurora, and Boulder connected and accessible for all.

Before diving into the history of the Flatiron Flyer service, it is important to look back on the history of the Denver-Boulder Turnpike and how the growing region led to the need for more connections between the two city centers.

In the early 1900s, the Denver region was growing fast, as was enrollment at the University of Colorado in Boulder, thanks in part to its V-12 Navy College Training Program offered during World War II to allow students a path to being commissioned in the United States Navy. At the time, there were no roadways that offered a direct route between the two cities, requiring travelers to navigate slow side streets to get to their destinations. The university, as well as local businesses in Boulder, championed a highway between the two cities to make it easier for Denverites to visit Boulder. Thus, the turnpike was born, opening as a 17.3-mile toll road on Jan. 19, 1952. Tolls were collected to pay for the construction of the turnpike through 1967, after which it became a freeway. In 1964, US 36 was realigned to the Denver-Boulder Turnpike, where it remains today.

In 2001, RTD, Colorado Department of Transportation (CDOT), and Denver Regional Council of Governments (DRCOG) partnered together to look at a future expansion of US 36, which would include potential bus rapid transit (BRT) service between Denver and Boulder along the thoroughfare. Funding for the BRT portion was approved by voters as part of the FasTracks transit expansion plan in 2004, with construction on components of the new BRT system taking place between 2006 and 2010, such as new bus pullouts, park-n-rides, and pedestrian bridges along US 36 at McCaslin Boulevard and the Arista neighborhood in Broomfield to accommodate the new stations at those locations, and new pullouts at Church Ranch Boulevard in Westminster to accommodate the new BRT stops along the westbound entrance and eastbound exit ramps. This phase would open to the public in 2010.
During this time, CDOT, in partnership with RTD and DRCOG, began developing a plan for a multi-year construction project to increase capacity along the highway. This plan would include widening both sides of the freeway to accommodate the addition of one new tolled express lane in each direction between the Interstate 70 and Foothills Parkway interchanges, as well as expanded shoulders for emergency and auxiliary vehicle access during periods of heavy traffic. This project would place a heavy focus on RTD’s BRT plans, too. New park-n-rides and stations, with bus pullouts and pedestrian bridges, would be built at the interchanges of US 36 and Sheridan and Table Mesa boulevards, transit signal priority lights would be installed at the interchanges of Sheridan Boulevard, Church Ranch Boulevard/104th Street, Northwest Parkway/Interlocken Loop, and McCaslin and Table Mesa boulevards, and new buses suitable for BRT use. The new BRT service would be called the Flatiron Flyer. Groundbreaking on the second phase of the BRT project began in 2013, with construction being completed in late 2015.

On January 3, 2016, the first Flatiron Flyer buses went into service, signifying a new era of accessibility for the northwest metro area. Ribbon-cutting ceremonies and celebratory events took place Jan. 7 at all six bus stations along the highway as hundreds of customers and community partners joined in. With the launch of the service, all customers had the opportunity to take advantage of all RTD services, including the Flatiron Flyer, at no cost to them all day long.
The Flatiron Flyer features regional coach-style buses, complete with reading lights and air vents at each seat, as well as storage space in the cabin and a dedicated luggage bay underneath for larger items. Each bus, manufactured by MCI, comes with a fully functional electronic accessibility lift for customers with mobility devices to use to board and alight the bus.

At launch, the Flatiron Flyer service comprised of five different branches, all of which utilized US 36. The Route FF1 is the flagship route of the BRT, providing service between Union Station in downtown Denver, all six stations along US 36, stops along Broadway in Boulder, and Downtown Boulder Station. The Route FF2, also called the Downtown Boulder Express, cuts out several stops between Union and Downtown Boulder stations, providing speedy service between the two stations, only stopping at US 36•Table Mesa and US 36•McCaslin stations along the way, as well as stops along Broadway and Table Mesa Boulevard in Boulder. Unlike routes FF1 and FF2, the Route FF3 continues to Boulder past US 36•Broomfield Station, allowing customers in Westminster and Broomfield to have their own express service. This route only serves Union, US 36•Sheridan, US 36•Church Ranch, and US 36•Broomfield stations.

While routes FF4 and FF5 still utilize US 36, they branch off to serve other areas of Boulder and Denver. The Route FF4 serves Boulder Junction at Depot Square and Wade Blank Civic Center stations, servicing stops along 28th Street in Boulder and all stations along US 36, except for US 36•Sheridan and Church Ranch stations. This route fills a key gap in service for those who live in the northwest metro area and commute to and from the Central Business District in downtown Denver. The Route FF5 provides a critical connection for both college students and workers alike needing to get to and from the University of Colorado Anschutz Medical Center in Aurora. This route provides service between Downtown Boulder Station and the medical center, serving the same stops along US 36 as the Route FF4 does. The final route, the Route FF6, provided service between Boulder Junction at Depot Square and Union stations. This route was suspended as part of the COVID-19 service reductions and remains suspended to this day with no estimated reinstatement date.

The Flatiron Flyer service remains one of the agency’s most used services, thanks to its ease of access and direct connections to the hearts of Denver and Boulder. In 2024, ridership exceeded 1.3 million, continuing a post-pandemic trend of consecutive years with ridership above one million boardings per year. Even in 2022, as the COVID-19 pandemic continued, boardings still exceeded one million, with 1,070,000 boardings that year. Since its launch, there have been over 10 million boardings across all Flatiron Flyer routes.

As the Flatiron Flyer enters its 10th year on Saturday, RTD is proud to see how the Flatiron Flyer has evolved into becoming a flagship service for the agency, and how it has become such a core part of its customers’ lives. It is a testament to the magic that can happen when entities work together in sync. Whether heading into the office in downtown Denver or heading up to Boulder to enjoy a Buffs football game, leave the driving to RTD and enjoy what the Flatiron Flyer has to offer.