CTA schedule cuts and reliability: Tracking Purple Line performance

Jul 14, 2023

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The RoundTable recently has received questions from readers about changes to service on the Chicago Transit Authority’s Purple Line, the el train line that runs through Evanston.

Here’s what we learned about reductions to scheduled service in the last few years, and how reliable the scheduled service is today.

The Purple Line’s schedule has changed significantly over the last two years. The CTA began implementing “optimized schedules” for every el line in October 2022 to “align scheduled service with currently available workforce,” according to a news release announcing the new schedule.

The staff shortage has been one of the CTA’s most pressing issues in recent months. In November, CTA President Dorval Carter Jr. told Chicago’s City Council that there were some 1,000 job vacancies for rail and bus operators. This shortage results in “gaps in service and delays in service,” Carter said at the time, leading to the optimizations now in place.

In a statement emailed to the RoundTable, CTA spokesperson Maddie Kilgannon wrote that the CTA has pursued “aggressive and comprehensive recruitment marketing efforts,” but that “as with all other workforces, just as new hires are brought on board, additional vacancies are being created through attrition or job promotions and reassignments.”

A RoundTable comparison of the Purple Line’s past and current schedules found that over the last two years, the number of train runs scheduled on the route each week has been cut by more than a sixth, with weekday service cuts exceeding 20%.

The RoundTable analyzed the Purple Line’s current schedule, implemented in March 2023, as well as previous schedules implemented in October 2021 and October 2022. In the analysis, local one-way trains counted as one run each, while express trains counted as two runs, since they eventually move through Evanston twice. Where older schedules listed estimated times such as “every 6 to 10 minutes” outside of express hours, the median time was used to find an average number of trains for that period.

Overall, the number of scheduled runs each week fell from the peak of 1,540 in October 2021 to 1,264 by March 2023 – a decrease of 17.9%, or slightly more than one out of six runs eliminated.

Breaking this into weekday and weekend totals shows the brunt of the reduction fell on weekday service, as 240 weekday runs were cut, 20.3% of the October 2021 schedule vs. only 36 weekend runs or 10.1% of what had been listed in 2021.

Separating local service from express service reveals that both were hit hard, losing 120 runs each, equal to 18.4% of local runs and 22.6% of express runs in October 2021. However, they weren’t hit at the same time.

Express service was reduced first, as 80 runs were cut from the October 2022 weekly schedule, just over 15% of the previous schedule. This was part of the “optimized schedule” implemented by the CTA to reduce inconsistency while the agency addresses staffing shortages.

The March 2023 schedule mostly cut purely local service. One hundred runs were cut from the workweek schedule, equal to a 15.7% reduction from the October 2022 schedule.

What this looks like day-to-day is a loss of 24 runs from each weekday, and a loss of 18 and 20 runs from Saturday and Sunday respectively.

Notably, these reductions do not reduce the Purple Line’s operating hours on any given day, as both local and express service are still scheduled to start and end around the same times as October 2021.

Kilgannon wrote that the CTA used used ridership and load-by-car data when identifying portions of the schedule to optimize in order to “minimize the impact on customers.” She shared a press release published Friday which details progress the CTA has made in the year since the agency launched its “Meeting the Moment” plan.

“Because of schedule optimization, the CTA is now able to fulfill a higher percentage of scheduled rides and provide riders with a more reliable schedule,” Kilgannon wrote. “The CTA continues to monitor ridership data as new trends develop and make service changes as appropriate and as workforce becomes available.”

Brandon McFadden, a Chicago transit organizer with Commuters Take Action, said he agrees with the optimization approach as a short-term improvement for the el’s reliability.

“When you have enough operators to run 100 trains a day, but you’re scheduling 150, then you’re going to run into those reliability issues,” McFadden said. “You’re just going to have missed departures because you don’t physically have someone there to take the train out along the line.”

He added, though, that “long term, they need to fix the personnel problem” in order to return to delivering full service across the el system.

The reliability of CTA schedules is key for riders’ use of the el. Reliability, in this case, is the percent of an el line’s scheduled runs that actually happen in a given period of time.

Both the CTA and McFadden track how reliably the el system sticks to its schedule, but the two data sets disagree dramatically, particularly on the Purple Line’s performance.

The CTA rolled out its new, online Performance Metrics dashboard on July 12, which includes a variety of data on the agency’s rail and bus systems and other operations. This includes monthly reliability data for individual rail and bus lines going back to July 2022. The agency previously published various other metrics in “Meeting the Moment” scorecards, but none included data specific to the Purple Line.

At the time of writing, the dashboard reports the Purple Line ran 94.6% of its scheduled trains in July 2023, exceeding the el system’s overall average of 88.4%. On weekdays when express service runs during rush hour, the Purple Line improves to running 96.1% of its scheduled trains, according to the CTA’s dashboard.

“While those numbers are strong, the CTA continues to look for ways to improve them even further, as we continue to address service reliability across the bus and rail network,” Kilgannon wrote in an email to the RoundTable.

While the CTA uses internal data to rate reliability, McFadden’s tracking relies on publicly available resources, including the agency’s schedule data for navigation apps and live Train Tracker Map. He’s updated this data on a daily basis since June 2022, publishing it to his website and sharing it through the Commuters Take Action account on X, formerly known as Twitter.

McFadden’s data shows the Purple Line following a volatile weekly pattern in recent weeks: reliability plummets near or below 50% on Saturdays, slightly improves on Sundays, and then shoots up to above 90% on Mondays. It then fluctuates throughout the work week, typically between 75% and 90%, before plummeting again on Saturday.

McFadden said this volatility may be another result of the staffing shortage, as the CTA has to prioritize which lines to run service on when there aren’t enough operators. He said his data shows a broadly inverse relationship between the Purple and Red lines’ performances: when one performs well the other tends to perform more poorly – with a notable exception.

“If there’s an operator shortage [on a given day], then the Purple Line might struggle in favor of giving the Red Line better service,” McFadden said. “Except during rush hour … when it’s doing its Loop runs, it [the Purple Line] actually runs almost all of them. It’s the most consistent and reliable service that we see out of the Purple Line.”

However, there is another possible explanation for the Purple Line’s volatility in McFadden’s data, which many riders may have encountered themselves: Trains can fail to appear on live tracking systems even though they are actually running, especially on short trips like the Purple Line’s local runs. This is true of both navigation apps like Google Maps and the CTA’s own Train Tracker map.

“I rely on data available to the public, where the CTA has internal metrics,” McFadden wrote in a message to the RoundTable. “Because of the length of the Purple Line, if it isn’t programmed into the tracker properly, my tracker won’t capture it, sadly.”

McFadden noted that the CTA has gradually improved the el system’s reliability in recent months. A “rolling average” chart on his website shows the system-wide seven-day average currently sits at 91%.

Kilgannon, the CTA spokesperson, told the RoundTable via email that improving the agency’s tracking system is part of its overall effort to improve reliability.

“Service reliability is dependent on our workforce, and updating the tracker will further complement those efforts,” Kilgannon wrote. “As we work towards addressing our workforce challenges, we are also working to improve our tracker system.”

Editor’s note: This story has been updated with a new statement and news release provided by the CTA.

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Alex Harrison reports on local government, public safety, developments, town-gown relations and more for the RoundTable. He graduated from Northwestern University's Medill School of Journalism in June... More by Alex Harrison