tag:blogger.com,1999:blog-2638543736544799966.post1523743360082433032..comments2023-10-17T14:32:04.734+01:00Comments on Thoughts of a Trainspotting Mathematician: What is... the Thameslink Programme?Dave McCormickhttp://www.blogger.com/profile/16226892437669224991noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-2638543736544799966.post-60679295891463575342016-05-22T05:40:40.392+01:002016-05-22T05:40:40.392+01:00A flat junction on the railway is much like a righ...<i>A flat junction on the railway is much like a right-turning lane on a dual carriageway: trains wanting to turn right must wait for a gap in trains coming the other direction to make the turn.</i><br /><br />But note that trains are guided, not manually steered. And all junctions are signalled, I understand that junction signals are set danger in all directions by default, clearing on demand. When the points are set to turn right, the signals for one direction on the continuing route are only clear if the signals for trains going the other way are at danger.<br /><br />Rail vehicles, whether for passengers or freight. unlike most road vehicles, but like buses, are all timetabled.<br /> I imagine that train timetables would be accommodate this conflict in the flat junction illustrated above so that trains in one direction turning right don't arrive at the same time as train going straight through in the other direction.<br /> This factor does limit the frequency of trains on both lines, if they are both operating at the same time. That said, these limits may be necessitated by level crossings, especially in the trunk section so that the headway between scheduled trains in the same direction is greater than the interval between the activation of the level crossing and the arrival of the fastest train.<br /><br />The flyover junction shown in the diagram above is one where one of the tracks of the divergent route goes over both tracks of the continuing line.<br /> Another type of grade separated branching is where where one direction traffic on each line is on a different level from opposite direction traffic on the same line.<br /> In case of a double track junction, this would mean one turnout on each level.Myrtonehttps://www.blogger.com/profile/06414825749856157045noreply@blogger.com