Here's why your BART car is so stiflingly hot



Click ahead to read our answers to your most burning BART questions. Why don't trains run 24 hours a day? Why does it take so long to fix broken cars?

Click ahead to read our answers to your most burning BART questions. Why don't trains run 24 hours a day? Why does it take so long to fix broken cars? Photo: Michael Short, Special To The Chronicle Photo: Michael Short, Special To The Chronicle Image 1 of / 19 Caption Close Here's why your BART car is so stiflingly hot 1 / 19 Back to Gallery

You know the feeling: You step into a BART car and are immediately hit with a wave of stagnant, desert-hot air. Trapped in the Transbay Tube, you start counting the minutes until you're at the next station where, despite the hot temperatures outside, the opening doors will still give you a second to gasp in some fresh air.

Why are some BART cars so darn hot? And what should you do if you're trapped in a sauna pod?

The reason why cars can reach Saharan temperatures should come as no surprise — the system was not built to be used by the number of commuters who utilize it today. The trains were originally built with vents near the windows to cool seated passengers, which is why when you're standing elbow-to-elbow, the air feels like it's never getting to you.

Add in the obvious (packed trains, hot outdoor temperatures, body heat, etc.) and you're in for an unpleasant ride.

Unfortunately, there's nothing your train driver can do to fix the problem. Unlike your vehicle, BART cars' air conditioning is not controlled by the driver. If you're suffering, the best thing to do is to note the car number (you can find this above the doors or near the intercom) call the driver on the intercom and let them know the problem. They can pass this information along to maintenance so the car can be inspected on its next maintenance cycle.

Once you've done that, you can try your luck in another car; air conditioning can be busted in one car and not another.

Our current stretch of hot weather complicates matters, too. As BART explains:

"Electronics are subject to damage when they become hot and the critical functions are propulsion and communications. When potential of overload occurs, such as when it is extremely hot or extremely cold outside, the non-essential functions (such as heat and A/C) automatically shut off to preserve the critical propulsion and communications features. The blower will continue to deliver a 'flow' or 'vent' but there is no heating or cooling."

As with most BART problems, this one should hopefully be fixed by the new train cars. They're built with modern HVAC systems and utilize ceiling vents, meaning the majority of us standing riders will finally feel the air.

In late 2016, BART said they hoped to have 60 new cars in service by the end of 2017, 230 by 2018, 420 by 2019, 610 by 2020 and all 775 by 2021.