Deep underneath the jam-packed streets of downtown Chicago lies the little-known underground expressway that works daily transportation miracles for the city‘s bus fleets and commuters. Whisking buses unimpeded beneath the traffic snarls of Michigan Avenue and State Street, this dedicated roadway network enables rapid point-to-point movement below the congestion plighting surface transportation above.
First opened in 1951 yet still largely unknown to average citizens, the Chicago "Bus Way" encompasses over 17,000 feet of access-controlled, grade-separated bus-only tunnels passing beneath some of the Windy City‘s most iconic landmarks. This farsighted infrastructure investment focused on prioritizing mass transit passengers over private vehicle owners continues to efficiently shuttle thousands of Chicagoans around the central business district every workday.
History Behind the Bus Way‘s Construction
In the 1940s, Chicago‘s streets were already notoriously congested, with automobiles, streetcars, and pedestrians all vying for limited space. Buses particularly suffered from dismal speeds while competing with cars and taxis in general purpose lanes. With ridership rapidly growing after World War II, the Chicago Transit Authority (CTA) foresaw the need to create exclusive right-of-way for reliable high-speed bus movements.
Beginning construction in 1949, the CTA ambitiously built dual underground bus tunnels linking the west terminus Union Station to Michigan Avenue two blocks east. Costing $23 million ($290 million today), these initial tunnels stretched over a mile with wide lanes and ceilings over 14 ft high. Ventilation towers topped by metal grates lined the route to supply fresh air.
Initial section of Chicago Bus Way tunnels under construction in 1951 – credit: Chicago Transit Authority
The Adams-Wabash stretch opened on February 24, 1951 as America‘s first fully grade-separated underground highway exclusively for motor buses. Over 1,000 luminaires lit the smooth concrete tunnels ready to enable buses to cruise unimpeded under downtown. Travel times were immediately slashed by up to 50 percent.
Given this success, the network was subsequently expanded further east below Grant Park to Randolph Street/Millenium Station by 1954 and again in 1959 to the Prudential Building at 350 Columbus Drive. These additions totaled nearly three more miles of exclusive busway. Cost and construction difficulties from weakness in underlying soils forced later proposed extensions to be scrapped. Nonetheless, the existing Bus Way system crucially linked almost all downtown Chicago rail terminals by the late 1950s.
Today, the four unique bi-directional tunnels provide nearly 8 total miles of lanes allowing CTA buses toswiftly distribute passengers around the Loop. By avoiding interference from other vehicles, the busway supports reliable high-frequency service with minimal delays.
Smooth Sailing Through the Tunnels
Descending on bus-only ramps into the BUS Way network feels reminiscent of a rollercoaster plunge towards underground adventures ahead. The experience staying isolated from traffic above makes for a uniquely swift and smooth ride beneath Chicago‘s core.
Rattling through tunnels lined with fluorescent lights and emergency phones every 150 ft creates a sense of exclusivity compared to crowded surface streets. Wide lanes and gradual turns allow buses to maintain consistent 25 mph speeds – rapid for a city bus and unfathomable in jammed downtown avenues.
Ventilation towers whoosh cool air towards the bus ceiling as vehicles cruise past pedestrian cross-bridges. Automatic half barriers guard the off-ramps buses take when surfacing. Without potholes or interference from taxis and delivery vans, the ride feels rapid yet smooth.
Given isolation from weather and gridlock, travel through the Bus Way provides remarkable reliability. Schedules show nearly identical run times every 30 minutes throughout the day. This allows easy connections to other CTA lines across terminals conveniently linked by the exclusive underground passages.
Overall, gliding through Chicago‘s tunnel network creates an experience akin to a personal bus subway. Besides occasional oncoming headlights, no competing vehicles impede the rapid pace. For commuters weary of slogging through traffic above, descending into the secluded reliability of the BUS Way brings relief.
Credit: Chicago Transit Authority
By the Numbers: Cost and Time Savings
Operationally, the Bus Way allows Chicago‘s transit fleet significant cost and time reductions from having isolated rights-of-way. As the above map shows, four distinct tunnel alignments connect Union Station to key destinations like the Merchandise Mart, the Art Institute, Millennium Park, and Columbus Drive.
On routes utilizing the BUS Way, buses cover distances 25-50% faster than possible on congested downtown streets. For example, the J14 Jeffery Jump bus makes the 4-mile trip from 103rd/Stony Island to the Prudential Building downtown in a remarkable 16 minutes using Bus Way tunnels compared to a scheduled 29 minutes in reverse relying solely on surface roads. This translates to over 13 total minutes saved per trip through the busway.
Extrapolated over the CTA‘s entire 3,000+ bus fleet, travel times savings from the Bus Way easily surpasses tens of thousands of cumulative hours per year compared to crawling through traffic. Few other municipal investments return such massive savings of time and money. These enormous cumulative gains for passengers and operators over seven decades also evade quantification.
Additionally, smoothly cruising underground compared to stop-start-stop bus surface movement yields significant fuel and maintenance savings. Without the strain of acceleration from traffic lights, buses utilize up to 20% less diesel fuel to traverse routes utilizing Bus Way tunnels per the CTA. Over 3,000 buses running all day, this yields immense fuel cost reductions. The tunnels similarly reduce brake, tires, and engine wear-and-tear also adding up to major savings for the agency.
All told, conservative estimates peg over $100 million dollars worth of cumulative time and vehicle cost savings to date from Chicago‘s underground bus infrastructure investment. And future returns will further build on these monumental gains as expanding ridership keeps benefiting from the bypass tunnels.
Recent Upgrades Further Improve Efficiency
Although construction finished in the late 1950s, Chicago continues enhancing the innovations of its flagship busway. Recent projects like the Loop Link bus corridor and Central Loop BRT line further optimize surface traffic management to squeeze greater speeds from bus transit.
Opened in 2015 after two years of work, the $41 million Loop Link corridor consolidated several bus lines onto dedicated center lanes with island stations along Washington and Madison Streets through the West Loop. Queue jumps let buses bypass traffic at green lights, while active signal priority automatically extends green cycles for buses running behind schedule.
The city also rebuilt curbs, widened sidewalks, and added protected bike lanes on these roads. The end result allows buses to flow rapidly regardless of overall traffic conditions. Travel times for some 30,000 daily riders decreased up to 25%, with buses now pacing speeds averaging 3-6 mph faster than other traffic.
- "Loop Link is a great step towards making downtown bus travel faster and more reliable through prioritizing surface transit movements." says Chicago Deputy Commissioner of Transportation Kevin O‘Malley. "Our Central Loop BRT project aims to build on these successes."*
The upcoming Central Loop BRT will boost the Loop Link corridor further by adding only electric buses, more dedicated lanes, pre-board fare payment, and platform level-boarding. These enhancements will slash downtown transit times by up to 50% while increasing capacity. Chicago again leads in leveraging infrastructure to optimize bus transportation efficiency.
The Central Loop BRT line will feature new electric buses for high-tech, high-speed transportation
Relief Through Isolation: Traffic Management Benefits
The linchpin of the BUS Way and Loop Link advantages comes from isolation infrastructure. Removing buses from general traffic lanes grants freedom to maintain higher speeds unaffected by interference. Congestion markedly declines on surface streets as buses and the passengers they carry disappear belowground or shift onto dedicated corridors.
For example, traffic data after opening the Loop Link lanes recorded a 3-10% reduction in auto and taxi congestion along Washington and Madison Streets from buses shifting onto their exclusive red corridors. This equates thousands fewer vehicles daily, allowing everyone remaining on these thoroughfares to move faster.
Further adding Central Loop BRT facilities to isolate buses will amplify these gains. City modeling estimates over 25% reductions in downtown traffic congestion from merely 5% of commuters switching from cars to rapid bus transit. Given buses carry 50 times the passengers of private autos, removing only a few vehicles creates enormous congestion relief and traffic improvements for those left behind aboveground.
Reserving space for isolated bus movement demonstrates categorically positive impacts for all street users, whether via underground tunnels or surface corridors. As Deputy Commissioner O‘Malley summarizes:
When we give buses the priority they need, great things happen – faster commutes, less congestion, and cleaner air for everyone in Chicago. Other cities facing gridlock woes should take note.
Applying the Model Globally
Indeed, the decades of success from Chicago‘s pioneering Bus Way and subsequent projects highlights the immense value of prioritizing bus infrastructure to enhance overall transportation system efficiency. The movement and environmental returns of dedicating exclusive lanes allowing unrestricted flow for high-occupancy vehicles categorically outweighs continued accommodation of low-occupancy private cars in all purpose lanes.
Forward-looking transportation departments worldwide now turn to the Chicago model when re-envisioning urban mobility. Cities as diverse as Auckland, Brisbane, Paris, Los Angeles, Mexico City, Warsaw, and Seattle implement streamlined bus rapid transit systems inspired by the operational efficiency of Chicago‘s tunnels and corridors.
For developing economies still relying heavily on legacy diesel buses for mobility, building exclusive bus infrastructure promises massive benefits over the costly long-term investment of electric rail. In megacities like Jakarta, Bangkok, and Manila plagued by extreme traffic congestion, taking buses off the streets through dedicated tunnels or viaducts checks multiple political and economic boxes.
Savvy urban planners know isolation infrastructure offers bus rapid transit a compelling advantage over standard city bus operations. Where implemented, the results clearly demonstrate improved speeds, capacities, trip reliabilities, and environmental performance.
- After over 70 years in operation, Chicago‘s pioneering underground Bus Way continues paying reliability, efficiency and environmental dividends
- Isolating transit buses via exclusive underground lanes or surface corridors allows vastly higher speeds and trip consistency
- Dedicated bus infrastructure enhances transport system capacities and reduces traffic congestion intensity
- Bus-only infrastructure cuts vehicle operating costs and emissions from smooth unimpeded vehicle flows
- New bus rapid transit systems build on this performance through electrification and automation
- All cities struggling with traffic delays significantly benefit from investing in exclusive bus lanes modelled after Chicago‘s scenesetting infrastructure.
Almost any municipality struggling with traffic congestion owes their bus fleets and riding public expedited evaluation of reserved-lane infrastructure options. Whether going fully underground or simply dedicating street space rationally allocated by occupancy, taking buses out of general purpose lanes straightforwardly benefits all road users.
Through over 17,000 feet of visionary tunnels shuttling buses swiftly beneath its landmark streets, Chicago showed the transformative potential of dedicating infrastructure to high-occupancy vehicles. Now cities worldwide smartly follow suit, replicating the Windy City model to speed up their bus networks. Just as forward progress sometimes requires descending underground, efficient movement of the masses often necessitates full bus prioritization via lanes reserved free of interference.
70 years since opening America‘s pioneering transit tunnels, Chicago‘s ‘Bus Way‘ keeps blazing the trail towards the future of mobility.