Wednesday was a rough day for two of the biggest public transit systems in the US. First, the Washington, DC, Metro shut down its train service for 29 hours Wednesday for safety inspections. Then on Wednesday night, electrical problems caused delays on the Bay Area Rapid Transit (BART) network.

And when BART customers complained on Twitter about yet another delay, the people behind the system's Twitter account started getting real.

Rather than a cheerful, anodyne apology for the delay and a promise to do better, they detailed the systemic problems afflicting mass transit in the Bay Area and elsewhere. They told their customers the truth: These issues aren't easy to fix, and Wednesday's delays are unlikely to be the last.

@shakatron BART was built to transport far fewer people, and much of our system has reached the end of its useful life. This is our reality. — SFBART (@SFBART) March 17, 2016

@tquad64 Planners in 1996 had no way of predicting the tech boom - track redundancy, new tunnels & transbay tubes are decades-long projects. — SFBART (@SFBART) March 17, 2016

@lisabari To illustrate this point - the number of people who exit at 19th street in Oakland has doubled in less than a decade. — SFBART (@SFBART) March 17, 2016

@CBonneaux We have to fix what we have first - our system was built to last about 45 years and we've reached that limit. — SFBART (@SFBART) March 17, 2016

@cliberti We have 3 hours a night to do maintenance on a system built to serve 100k per week that now serves 430k per day. #ThisIsOurReality — SFBART (@SFBART) March 17, 2016

@cliberti The magnitude of repair projects is too great to do during our 3 hour maintenance window. 1/2 the time would be spent staging. — SFBART (@SFBART) March 17, 2016

The last trains are leaving the end of each line within the next 15 mins - it's been a great conversation. Goodnight. #BayAreaRidesTogether — SFBART (@SFBART) March 17, 2016

This isn't just a Bay Area problem — its transit agency is just being unusually honest. Mass transit systems throughout the US are in very, very bad shape. A study in 2010 by the Federal Transit Administration found that 26 percent of rail mass transit systems were in poor or marginal condition.

An association of most of the nation's largest transit systems — including BART and DC's WMATA — reported in 2015 that transit systems need $104 billion in backlogged repairs in order to bring them up to good working order. They're not getting it, and the backlog keeps growing.

Go deeper:

Another problem: Transportation projects in the US are really, really not cost-efficient, as Vox's Matt Yglesias wrote in December 2014.

Second Avenue Sagas wrote about why New York's subway system has deferred maintenance for so long.

The full report on transit repair backlogs shows just how pervasive the problem is.

220 years of population shifts in one map