auf Twitter hat Network Rail SouthEast einen Thread gestartet, in dem erklärt wird, warum manchmal einige Züge andere überholen. Auch wenn das ein bisschen unübersichtlich ist, habe ich alle Beiträge dieses Threads mal hier eingebettet.
“Why did my @Se_Railway train get held at Hither Green and another let in front of it? What is your signaller doing?!” We get asked this occasionally, not always so politely, so we sat down with Dan the ops man for Kent to find out. THREAD 1/ pic.twitter.com/JbUQBRXpa7
The way some trains are held and others let through is called “regulating”. Junctions where trains meet each other are “regulating points” and the principles are all written down for signallers at each location and agreed with operators. 2/
In Kent (not so muchSussex, whichhasitsownagreements) trainsarelargelyregulatedforPPM (publicperformancemeasure) asthatis themetricthatoperatorsaremeasuredbyin theSouth East. This meansa trainiswithinPPM ifitiswithin5mins ofbookedtime. 3/
That means that if a train is 2mins late it will be held at a junction to allow an on-time train to pass, to protect that train’s punctuality. Which is fine if you are not on it. It can also have unintended consequences where the railway is very busy, as we shall see. 4/ pic.twitter.com/ZYETudoeLR
.@se_railway will knowsometrainsarevital becausethestock hasa tightturnround+ thesame withthecrew. Theygetprotected. Therewas a trainon anotherpartofourrailwaythatcarried4 driversaspassengerseachdayandifitgotheldupitspreaddelayseverywhere. 5/
...Hence, sometimesMetro trainsstoppedatHitherGreen will spota bluetrainwhistlingpastandwonderwhy. This mapshowssomeoftheplaceswemakeregulatingdecisionson Hastings toCannon St trains+ howdifficultthatcanbe. 7/ pic.twitter.com/cdFSP5HBUZ
Bytheend oftheyearSouth East Route will berunning6,000 trainseveryweekday. That’smorethanmostcountries. In someplacesthepermutationsofwhichtraintoregulateareso complex, nobodycanunderstandit. So whatcanwedo? 8/