Ooops
The monorail line in Seattle is double-tracked. On most of the route of the monorail, there's nothing wrong with this, but there's apparently a spot where the two tracks squeeze together closely enough so that there's not enough room to fit both trains side by side. For 43 years, this was not a problem.
oops!
The last few years have not been particularly good for monorails in Seattle, between the ongoing New! Monorail! Just! Like! Disney! scam and the fire that damaged the Blue Alweg car (do they have fleet numbers, or are they just Red car and Blue car?) Perhaps when the New! Monorail! project climbs out of the grave again they should not just extend the existing Alweg line, but re-engineer this monorail-equivalent-of-a-gantlet-track so that trains can pass on it?
(picture and link from the Seattle Post-Intelligencer)