The majority of CTA rides are on-time and uneventful, but sometimes service can be disrupted. Here’s what we do about it.
On an average weekday, the CTA provides over 1.5 million rides on its buses and trains. If that were a city population, it'd be in the seventh-largest city in the United States (or, in other words, that’s more rides than if the entire population of San Antonio took a ride on one of our buses or trains in a single day).
To provide this many rides, we need to provide a lot of service: ‘L’ trains travel about 233,906 miles on a typical weekday (about seven times the circumference of the Earth at the equator!). Our more than 1,800 buses travel over 161,192 miles on a typical weekday (almost another six times around the Earth).
Together, our vehicles, on an average weekday, travel the distance of almost a full trip to the moon and back! 🚇🚀🌕
Suffice it to say, we run a lot of service. And those trips are on-time and uneventful—but with a system this large, complex and busy, problems can occur and a delay at just the wrong time can affect the commute of thousands of people at once.
Many things can cause a delay to transit service, and it's often due to something entirely out of CTA's control, such as roadway congestion and situations that require help from emergency responders (like a person becoming ill and unable to be helped off a train). Though CTA vehicles are well-maintained by experienced staff, mechanical issues can still occur, just as with any vehicle that travels hundreds of miles every day.
Regardless of the cause of a problem, there are many things we do to address them both during and after an incident. We also work hard to prevent them in the first place. We have one overriding goal: To keep our buses and trains running safely and on time 24/7.
To help you better understand a few of the challenges we—as the nation’s second-largest transit system—face, we’ve put together this informal overview that covers some of the causes for delays and what we do to address them.
On this page
On the ‘L’ System
Why do delays happen on the ‘L’ and what do you do about them?
Rail networks are complicated systems and there are a lot of variables that can affect service. The cause of delays can range from equipment problems to people becoming ill during their commute.
Knowing that we must deal with the unexpected every day, our schedulers design a little wiggle room into the schedule—this allows for most run-of-the-mill delays, which can be compensated for by a train by simply continuing without further interruption. We also have service management staff strategically placed around the system to be able to help train operators in the event of a problem they can't quickly solve themselves.
If a delay occurs at the peak of a rush period—even for just a few minutes—it can cause trains to quickly back-up, resulting in an area of rolling congestion and/or gaps in service in front of the delayed train.
Delays can quickly become compounded: For example, once something has delayed a train, more people will be waiting at stations ahead and the delayed train can become crowded, leaving people behind at each platform. It can then also lead to a train taking longer to stop at each station, falling further behind schedule and the overall impact of a delay gets worse, even though there's no specific stoppage.
When a delay has occurred, we sometimes have to implement what are known as "service restoration techniques" to space trains out (i.e., running a train express or briefly holding trains at stations across the rail line). These options are carefully considered and weighed by experienced service management personnel, because we know they also can cause some additional inconveniences for some riders.
Behind the scenes, we're also doing a lot to help reduce delays and improve the quality of service on the 'L'! Though we've upgraded huge portions of the 'L' system, we continue to perform a variety of track and signal upgrades to improve aging track or equipment that we haven't yet gotten to through replacement, reconstruction or repair. To improve the reliability of service, we’ve also been performing mid-life overhauls or purchasing new buses and rail cars to replace the oldest vehicles in our fleet, which are more prone to mechanical issues and failures, which adversely affects service and can be costly.
You can learn about some of the efforts we’ve taken to mitigate delays -- and boost line capacity accommodate booming demand in the future on this page.
Still, there are times when delays simply cannot be avoided and will occur without warning, as is true and part of day-to-day operations of any rail system as busy as ours anywhere in the world.
Here, we'll outline some of the more common causes of delays, why they happen, and what we do about them...
Equipment problems (trains, signals, switches, etc.)
Just as bicycles get flats and automobiles sometimes break down, train cars—full of complex mechanisms and technology—encounter occasional problems too.
On a train
For the most part, our trains run very well. If any one of the many thousands of components on our nearly ~1,500 railcars fails, it can result in a delay and affect the quality of service along its route.
Our operators do more than just drive the train--they go through extensive training and have a great deal of experience for solving problems on-the-go. An 8-car train, for example, has:
- 32 sets of side doors,
- 32 motors under the floor,
- more than 64 braking mechanisms
- and countless onboard systems for passenger comfort, safety, communications and more.
Any problem detected with any of these systems or components can prevent a train from moving or require the vehicle to be removed from service.
For example, if the safety mechanisms on our doors aren't able to confirm each door is properly closed and locked after a station stop, the train won't be able to leave the station until the operator has sufficiently addressed issue (possibly needing to remove the doors from service and block them off).
Our operators are trained to troubleshoot and mitigate just about any of these and typically only need a few minutes to troubleshoot and get a train moving again.
At a junction or other track switching location
If a track junction experiences a problem, such as the loss of signals (which can occur if there's an area power outage), we may have to manually operate the switches to get trains moving through the junction safely. This takes extra time and can require trains to operate at restricted speeds to ensure your safety. Signal and switch maintainers are on duty at all hours and, in the event a problem occurs, they often arrive in minutes to begin resolving any issues.
With nearly 1,500 railcars traveling more than 200,000 miles a day over 200 miles of track, it’s a tough job and it takes a lot of people working 'round-the-clock, to keep Chicago moving.
Sick Passenger / Medical Emergency
If a person requires medical attention on a train and is unable to walk, move or is unconscious (meaning we can't safely assist this person off the train ourselves), we may need to hold a train at a station until paramedics can arrive and provide needed assistance.
Every rider's health and safety is a top priority for us, so please be understanding in the event someone becomes ill or needs medical attention. If you see someone who is sick or injured, please notify the nearest employee and/or call 911 right away! (Call buttons are located in each railcar so you can talk to the train operator—look for the blue tinted section of the overhead lights in your car.)
There are a variety of reasons police may require us to halt service on a route and we take safety concerns very seriously. If we see or someone reports a suspicious package, for example, police may ask us to stop trains while they investigate.
Although crime on CTA is actually very rare, sometimes the police may ask us to stop service while they look for a suspect or even evidence as part of a crime that was committed on or near CTA property.
If an employee is alerted to an unauthorized person on the tracks or trespassing in a subway tunnel, we cut power immediately so they aren't at risk of harm from the electrified third rail and/or moving trains. If in the event CTA personnel are unable to get the trespasser(s) off the tracks, we may need to wait for police to respond and remove the trespasser before we can restore power and service.
Minor track fires / reports of smoke / fire department activity
If we receive a report of smoke in a subway, this can also cause delays or a stoppage. Smoke does not always mean fire—in fact, it rarely does. Smoke can be drafted in from the street above when someone is cooking or lighting a grill near subway air vents, or the smoke could result from an equipment problem such as a set of brakes being stuck and rubbing against a wheel while a train is moving.
Regardless, whenever there is a report of smoke in the subway, we must investigate it and the fire department may additionally require us to hold service until they arrive and inspect the area before letting us resume service. (Again, safety always comes first!)
On an electric railway like ours, minor track fires can sometimes occur, too. For example, debris (i.e. newspapers and food wrappers, etc.) can get blown into subway tunnels by strong air currents as trains enter and leave stations. Once on the tracks, debris can collect and become kindling for fires, which can occur since sparks are a normal thing under electric trains powered via third rail.
To help avoid disruptions to service, please don't leave trash or newspapers on benches, on the ground, on top of bins or other station equipment or platform furniture—always put papers or trash in a recycling bin or trash bin, where they belong.
We also ask that you don't leave trash or newspapers in the train, either, since they can get blown or tracked out of the car and end up on the tracks, too.
Fires near our tracks
Of course, our lines run right through neighborhoods and neighboring communities, often right next to houses and businesses, which have built up around our services. Fires next to our tracks can cause delays, too: In 2011, for example, a large fire broke out at furniture warehouse next to the elevated tracks just north of Fullerton Avenue—causing a disruption to Red, Brown and Purple line service for about four hours. We were able to restore service only after the fire department determined it was safe to do so but it did delay a lot of people unavoidably that night.
Keeping you informed
One of our biggest priorities during an incident is keeping you informed of what’s going on and to help you make informed decisions when the unexpected happens. To do this, we use multiple channels: Platform and onboard announcements, alerts on our website (or sent directly to you by e-mail and text), electronic information screens and even on Twitter.
The nature of every incident is different, and disruptions by their very nature are fast-changing—as is the information about them. We’ve recently implemented a number of improvements to how we communicate delays consistently and in a widespread manner, and we're always working on ways to do more.
What kind of improvements are you make more reliable?
In recent years, much has been done to improve the reliability ‘L’ service: Red and Blue line subway track, signals and switches have been renovated or completely replaced in recent years; the tracks on the Dan Ryan branch (the South Side part of the Red Line) was completely rebuilt; and major track replacement work on parts of the Blue Line's O'Hare Branch and Ravenswood-Loop Connector (used by Brown and Purple Line trains between Armitage and the Mart) have been completed over the last few summers making tracks like-new, again.
Further, major projects are getting underway, such as the Red and Purple Modernization project to improve the North branches of the Red and Purple lines . A fleet of over 700 new railcars—the 5000-series—was delivered in 2011, which allowed us to expand our fleet and retire hundreds of old railcars.
Coming soon, the new 7000-series railcars, which are set to replace hundreds more aging rail cars with all-new, state-of-the-art cars, are already ordered and are expected to begin arriving in the next few years!
You can read more about how we're improving our system (tracks, stations and vehicles included!) in the System Improvement Projects section of our website.
Why do trains sometimes break down?
Our maintenance crews work hard to keep our vehicles and other operating equipment in good shape. Many of our railcars have been in service since the 1980s, however, and some are now approaching twenty years beyond what their designers would reasonably have expected.
The good news is that we've just replaced about half our fleet and our oldest railcars (some dating to the late 1960s) have been retired and replaced with modern 5000-series cars, which feature state-of-the-art propulsion technologies and other features for better reliability.
The average age of our fleet is now much younger than it was just a few years ago, reducing maintenance needs and the number of failures that occur, but we still have to keep some decades-old rail cars running that are pending replacement.
New technology helps us identify and fix issues more quickly, and the recent new car delivery allowed us to increase the number of cars available for service.
We're also overhauling our 3200-series cars (at present, primarily used on the Brown and Orange Lines), previously our fleet’s newest cars, as they are now more than 20 years old and due for a mid-life rehabilitation to extend their life and improve their own reliability, further.
The good news is that we'll be replacing more of our fleet with an even newer series of rail car—the 7000-series, which have been ordered and we expect to begin receiving soon—starting as early as 2020.
Why do Red Line trains sometimes get rerouted via the elevated lines—or Pink Line trains onto the Blue Line tracks?
If something halts service in the subway, the Red Line has the special advantage of being able to be rerouted away from the subway via elevated lines. This way, trains can still make the whole trip between Howard and 95th via downtown.
We sometimes refer to this as Red Line trains being rerouted “over the top.”
A similar situation is when something disrupts or severely delays Pink Line service into the Loop. If this occurs, we sometimes will use a track connection between the Pink and Blue lines near Polk to divert Pink Line trains onto the Blue Line just up to Racine. This allows us to provide Pink Line riders a same-platform transfer to continue their trip downtown via subway (instead of having to ask people to transfer to a shuttle bus which can get stuck in unavoidable traffic). This alternative plan also helps us more efficiently turn Green Line trains back toward the Harlem/Lake terminal with fewer delays and less congestion if both lines must be disrupted.
There are a number of other, common reroutes we might implement, too, such as sending Brown Line trains into the subway if there's a problem on their elevated routing, or “through-routing” Brown and Orange line trains via half of the Loop ‘L’ if there's an event that limits or disrupts service on one side of the Loop Elevated.
Why does my train keep stopping for signal clearance?
In addition to when you have to wait for other trains to clear at a junction, trains are kept at a safe distance from the train ahead of it by our signal systems, which are designed to tell trains to stop if there's a train occupying the tracks ahead.
If a train incurs a delay during very busy times, this can create a ripple effect for the trains behind it. Your train can only move ahead so far before the signal system alerts your train operator to stop and wait at a safe distance for the train ahead to move.
Though congestion can happen anywhere on any railway where trains have gotten too close together, it can be worse when several trains approach a junction at once. Take for example the junction at Wells and Lake on our Loop Elevated where five of our eight rail lines intersect: Here, a southbound Purple Line train could have to wait for an approaching Orange, Green and Pink line train to clear the junction before it can be cleared to turn left to enter Clark/Lake.
It's kind of like what happens at a stop sign—if there's light traffic, with just two or three cars going through, the wait isn't long and it's barely noticeable. But if there's 20 cars that come all at once, traffic can crawl through the intersection ahead and you might have to wait a while to get up to the stop sign yourself and finally proceed.
Though there are fewer trains than cars on some roads, 8-car 'L' trains are a lot longer and, because they're also much heavier than cars, require more space as a buffer to ensure safe stopping distances.
As a result, a delay during busy hours can back up further than just 20 cars on a street at a stop sign.
Why do you run trains “express?”
Running a train “express”—not stopping at stations it normally would stop at—is a way to alleviate congestion following a delay.
A delay can cause a gap in service, and it’s important we try to keep service evenly distributed across a route. Not only does running an express train allow that first train after the delay to get ahead and fill a gap in service, it also helps to alleviate the congestion effects behind the delay so more trains can get moving more quickly, at once.
A reason that it's really important to close gaps is because if we don't, that first train may become extremely crowded and incur additional delay at each stop due to the train taking longer to exchange passengers at each stop, while leaving more and more people behind at platforms.
By sending one or more trains express to spread them out, multiple trains can then simultaneously start picking up waiting passengers across multiple stations past hte delay at once, delivering more capacity more quickly and leading to overall faster travel times.
We understand that it may not feel like a very good solution if you’re on an express train that doesn’t serve your stop (or are waiting and see a train go by), but we sometimes must look at the larger picture of the route and work to restore the intervals between trains.
When deciding whether to send a train express, staff does their best to determine:
- whether or not closing a gap would cause more crowding than it might solve,
- whether following trains are close enough behind to quickly accommodate those bypassed by an express train, and
- overall how to get everything back to normal ASAP.
Why did my train wait due to a delay elsewhere on the line?
To manage service across a rail line in a way that can minimize the impact of developing or ongoing delay, we may sometimes hold trains during a delay both ahead and behind the delayed train to help keep service more evenly spaced. (This is a common strategy as part of managing service intervals on busy transit lines, used by us and other big city transit systems around the world.)
By holding some trains, we help to avoid big gaps in service from forming ahead of a delay and reduce the potential for crowded trains and platforms, long waits and the additional delays that might occur after the original delay is cleared as a result.
On the Bus System
What causes bus delays?
Bus systems, because they have to deal with so many external influences beyond our control, are a big challenge to design.
Our service schedulers carefully weigh a variety of factors when writing schedules while trying to provision service in a way that makes the most of limited resources. These data-driven considerations include historical run times, ridership trends, school bell schedules, traffic conditions, construction projects, as well as the potential for any number of “unknowns."
The work they do is intricate—planners add a half-minute to a trip here, shave a half-minute there—all applied in massive, schedule updates that occur every few months to accommodate for changing traffic and ridership patterns, as well as seasonal changes (such as when school is in or more people traveling to the beach or tourist destinations).
Analysis of huge quantities of data collected by buses using GPS devices, passenger counters and more is done to help inform our schedulers and drive these refinements to accommodate demand and run an efficient service.
Though our bus schedules are created with a bit of room for expected delays and service impacts, unusual and unexpected delays out of our control still occur. When a significant delay happens, it can sometimes quickly snowball, resulting in gaps in service and bunches of buses trying to accommodate waiting passengers behind a gap. Unfortunately, this easily occurs along our most heavily traveled routes where service is more frequent. Often, these high-frequency routes serve streets that host high volumes of vehicular traffic, so external influences on service can sometimes be greater there.
We’ll try to explain how and why these things happen, and what we do to minimize it, and why it’s not something that can easily be altogether prevented.
Why do big gaps form and buses bunch up?
Bus bunching is frustrating. It frustrates us too, not only as the people who work very hard to deliver high-quality transit service for the communities in which we live, but also as experienced bus riders, ourselves.
Bunching is the bane of bus systems around the world and it's by no means unique to Chicago. Unfortunately, there isn't an easy fix for it. The phenomenon is an especially difficult challenge for transit agencies that operate service on busy streets with heavy traffic and where frequent service is required.
How does bunching happen? Here’s just one scenario:
Imagine a busy route that has buses running about every 5 minutes during the morning rush.
Everything's great until a large truck backing into a dock blocks the street for a bit, delaying a bus just 2 ½ minutes.
No big deal—it was just one bus sitting for a couple of minutes, right?
Unfortunately, this seemingly minor delay actually amounts to a 50% increase in the space between that bus and the one ahead of it. (Instead of every five minutes, there's now a 7½ minute gap, and then two buses 2½ minutes apart.)
Assuming a pretty steady flow of people are approaching stops along this route, this can mean 50% more people are now waiting to board the bus at every stop up ahead, meaning that the bus takes a little longer than usual at each stop, adding valuable seconds to how long a bus is stopped at each stop ahead. (We call this an "increase in dwell times" in the transit world).
The bus is now likely to have to stop at every stop (even if no one is waiting at the stop) because the greater number of passengers already on board than usual need to get off at a higher share of upcoming stops.
These factors can lead to the bus falling further and further behind schedule and, meanwhile, meanwhile, that bus’s “follower” (the bus behind it), has begun to catch up.
Even if the following bus has a similar delay, by already being closer behind the delayed bus in the first place, it's easier for the follower to keep a normal pace and stay on schedule, since the stops ahead of it were more recently served than the schedule designed and they can make up delays they experience more easily.
In fact, the driver might even need to slow down or stand for a bit to keep from getting ahead of schedule (one of the things that we can and do control by having the on-board computer on the bus tell the driver if they're getting ahead, since this can cause gaps, increased dwell times, and thus delays further back along the line).
Despite this following driver doing a good job of staying on-time, she still catches up to her leader and a bunch is formed as the first one gets more delayed.
Just that quickly, a "bunch" of two buses come together, after a ten minute gap in service, the two buses can together can still fall further behind, because they begin leapfrogging and serving nearly every stop together.
If just a few more minutes of added delay occurs, a third bus will have caught up...All because of an unavoidable delay of just a couple of minutes a few miles back!
At the end of the line, the terminal may “absorb” the delay because some time for a "layover" is often scheduled at the end of a trip. But, if they end up falling too far behind, a gap can even ripple all the way into the spacing of bus service in the other direction.
This is where our Bus Service Management staff become crucial to minimizing delays and inconveniences: They can use a number of techniques to restore regular service, such as directing the bus to run express or adding a “fill in” run from another route.
Chicago Public Radio's Curious City did a story on bus bunching and why it happens (and how it’s virtually impossible for any large bus system to eliminate it completely). You can read the story here, and check out this handy animation they made, explaining it:
So what can we do to address a bunch, or prevent them in the first place?
The answers aren't always easy, but we do have a number of tools in our toolkit to mitigate unavoidable delays. Here are some examples:
Run a delayed bus "express": We can try to have one or more of the buses caught in a “bunch” run non-stop to get further ahead. However, this is inconvenient and frustrating for people who've already been waiting a long time at stops only to finally see an approaching bus breeze by (especially if the bus is not full).
This strategy can also be a problem for people already on the bus who need to get off in the area that we wish to bypass—to accommodate those riders, an additional delay may then be incurred as service managers coordinate to let passengers off one bus and get them onto the one behind it.
Because of the potential for added inconvenience and frustration for riders and new delays that can come from implementing it, we need to use this option minimally.
"Short turns": In some circumstances, we can do what's called "short turning" a bus, which means having a bus that's mid-route end its trip early, turn back to go into service the other way, short of the end of its route. This can fill in a gap going the other way.
This restoration technique is difficult to implement, though, as it may require special coordination to ensure that riders exiting the first bus have another bus immediately there to pick them up—and it can only be done if the bus behind it can accommodate all the people from the first bus. (Otherwise, a new problem is created by doing it.)
Side note: When you see a bus not going all the way to the end of a route, it's not always from a delay—many routes have scheduled service that goes only part of the way, as extra service that's focused on busier parts of a route as a matter of efficiently delivering resources with the resources we have.
As a preventative measure, we do schedule in extra wiggle-room to allow for run-of-the-mill delays. However, this extra time increases the length of each trip, so we also have to be careful not to add too much. (Too much wiggle-room can create gaps, force buses to go slow to stay on schedule and not create gaps behind it, or even cost money in wasted man-hours.) Our schedulers work diligently to find just the right balance here and not pad in too much.
As another preventative measure, scheduling more service can be an option that helps against the likelihood that a delay becomes compounded by crowding but we also have to be careful not to spend money on excess capacity in one place at the expense of somewhere else that really needs it.
Suffice it to say, there really isn't a silver bullet for solving bus bunching and it's a problem that affects every busy bus system around the world. Corrective actions can be complicated and need a lot of people and pieces to come together in just the right way to really break up a bunch which is why you'll see bunching on any big city transit.
We continue to work to improve service and regularly work to find new ways to prevent things like bunching, including evaluating new technology and implementing strategies to address it.
However, our buses continue to be at the mercy of street traffic from accidents and problems just like other vehicles on the road, but with far less flexibility to adjust routes and stops since people depend on service following usable patterns.
Why did my bus go down the street slowly and/or purposely miss a green light?
We understand how frustrating this is, but this is a necessary evil in the big-picture of how to operate the best possible service. Here are the basics:
In the event that everything lines up in such a way that traffic is lighter than normal, and no events cause a delay to service, buses can get ahead of schedule because there’s some wiggle room built into schedules to help mitigate delays and variability.
We refer to being early as "running hot."
The problem is that if a bus "runs hot," it creates some problems:
During off-peak hours, running hot can cause a person trying to catch a specific bus to miss it, and then have to wait a full scheduled wait, plus the amount time they arrived early at the stop.
During higher-frequency service, a larger-than-normal gap behind a bus that's running hot leads to the following bus having more passengers than usual, slowing it down and potentially leading to a bus bunch behind it.
Either way, being ahead of schedule creates a gap in service and, potentially, one that’ll lead to bus bunching by increasing the number of people getting on and off the bus behind it, causing it to take longer and longer at each stop.
Since being early is one of few variables that can cause big inconveniences and is a variable that we can completely control and avoid, it’s in our procedures to simply not "run hot."
While it may be frustrating, keeping with the schedule, and not getting ahead of it, is an important, strategic procedure that helps us make the system more reliable, in general.
Some additional thoughts
Delays on high-frequency services like ours are a problem that every major transit system faces. As much as we'd love to be able to, it’s simply not possible to account for every variable and anticipate delays caused by external factors. Further, the solutions to when inevitable delays occur are not always easy or quick to implement. We do, however, try to do everything possible to keep your service running on time.
We want you to know that we're very aware of how delays can affect your day and we experience these same frustrations ourselves, as transit riders, who appreciate and believe in how important transit is to everyone's quality of life in and around Chicago—and part of what makes it such an amazing place to live.
Providing a good service that improves your quality of life is a passion for us, and we think about how to find creative solutions to problems and, in general, how we can do better all the time.
While a good trip, generally, is a trip you don’t remember (you get on, you go, you get to where you’re going and never have to think about it again), we also know that it’s those bad trips that stand out. For every time you experience a delay, there are probably a dozen delays that were averted or alleviated because of talented people in the field working hard to keep you on the move. This is in addition to all those times where things just worked the way they should in the first place.
When a train breaks down, we usually have it back up and running in just a few minutes and only a small percentage of our buses actually are arriving at stops within a minute of another—but we know those times are the ones you're more likely to remember and we work hard to minimize how often that happens further.
To understand the quality of our service and look for opportunities to make it even better, we extensively monitor and keep track of our performance and quality of service, and are constantly responding to delays that crop up so, hopefully, it never gets big enough to affect you.
We also appreciate our responsibility to provide you with a better service, and as part of the effort, we work to give you tools to find the best way to get you going where you need to go, such as Bus Tracker and Train Tracker, new cars, new tracks and other service improvements that are part of what we do year in and year out.
As always, we welcome feedback, which we regularly use to improve service. You can reach us via phone (1-888-YOUR-CTA), e-mail or social media (@cta on Twitter, facebook.com/thecta).
Further, please feel free to check out our Performance Metrics to see how we’re doing—and also the App Center to find some of the nifty things the community has put together with data we publish about our system.
Thank you for riding the CTA.