It's already been a tough week for Caltrain riders and it's only Wednesday.
Many commuters say mechanical delays are becoming intolerable as the aging system limps toward getting a fully upgraded electric train fleet by 2019.
The most recent troubles started early Monday morning when a speedometer failed on a northbound train, delaying northbound trains by up to 20 minutes. Brake problems on another train, followed by a person on the tracks at San Francisco's Bayshore station, compounded delays throughout the morning — with some passengers reporting wait times of more than an hour.
Mechanical problems hit the system again Tuesday. One northbound train died between Burlingame and Millbrae for about 15 minutes, and another northbound train was stuck at San Jose's Diridon station with brake issues.
Again, 20 minute delays rippled through the system for most of the morning commute.
"We want to apologize to our riders," said Caltrain spokeswoman Christine Dunn. "We understand how frustrating it is to have these kind of delays when you're just trying to get to work."
Dunn said Caltrain has an aging fleet, with 20 of the system's 29 diesel locomotives chugging past their 25th birthdays in recent years.
"Generally speaking, a diesel locomotive is expected to last 25 to 30 years, so these are nearing the end of their service life," she said.
Data provided by Caltrain show the system rarely meets the goal of 95 percent of trains leaving within five minutes of their scheduled time. Trains do usually leave within 10 minutes, with some exceptions — like in October, when about 83 percent were within 5 minutes and 91 percent were within 10 minutes.
With plans to upgrade to a fully electric fleet by 2019, Dunn said it doesn't make financial sense to upgrade any of the aging locomotives now.
But some passengers aren't willing to wait.
San Francisco resident Jon Marcus said he quit his job in Mountain View this summer largely because he couldn't stand taking Caltrain anymore.
"It was just a long, awful commute," he said. "The trains are overheated. They're unreliable."
But Marcus is likely not the norm. Caltrain has seen skyrocketing ridership, and now estimates a more than 47,000 average weekday ridership.
About 67 percent of Caltrain riders reported being satisfied with how frequently trains arrived on time at their destinations. The responses were collected in a Caltrain-commissioned customer satisfaction survey released in April.
Dunn said she "certainly hopes" passengers won't see more frequent mechanical delays as the trains continue to age. She said the system will be "redoubling" efforts to keep the trains maintained, but it won't be adding staff or hours or inspecting more frequently.
Correction: This story was updated Sept. 19 to correct a quote from Caltrain spokeswoman Christine Dunn. When discussing the transit system’s train fleet, she said, “Generally speaking, a diesel locomotive is expected to last 25 to 30 years, so these are nearing the end of their service life.”