Predicted arrival times on NextMuni signs at transit stops and on NextMuni/NextBus apps are particularly daunting this week — 85 minutes for the N Judah? — and wildly, totally wrong. To blame is a glitch that's rendered as many as 40 percent of buses and Muni vehicles "invisible" to the NextMuni system: A bus or light rail train could arrive far sooner than indicated, but the problem, which emerged this week, is not expected to be resolved for several weeks.

Muni officials wrote to the SFMTA blog to explain the problem: NextMuni, which is a customized name for the third-party vehicle tracking system NextBus, relies on infrastructure installed in 2002 that only has 2G wireless network capacity. That outdated technology is being replaced nationwide by AT&T, Muni's provider. The issue, according to Muni, is that "The deactivation work that affects our vehicles started sooner than expected and outpaced our ongoing upgrade of all Muni vehicles to a new communications and monitoring system."

Put another way, "Muni vehicles that aren't yet upgraded aren't transmitting data to NextMuni to predict their arrival." As SFMTA spokesperson Paul Rose tells SFBay, as many as 40 percent of Muni's fleet of vehicles, trains included, don't have the new, 3G communications systems in place.

Rose says his agency is "working aggressively" to resolve the problem, but as indicated in the official Muni blog post, it could take weeks to get all the Muni buses back onboard, so to speak.

It's more damaging news for the technical reputation of a transit agency that was hacked by a ransomware spammer after Thanksgiving, and hasn't exactly been a beacon of reliability over the years. Should we trust the expected wait time for this glitch to be fixed, or at this point, are all predictions off?

Related: Friday The 13th Will Mark The Arrival Of Muni's First New 'Fleet Of The Future' Train

Seen on NextMuni on Wednesday night at 8:30 (image cropped a bit). What's wrong with this picture?