Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
Display:
My focus above is on branch/main line junctions, rather than main/main line junctions, and branch/main junctions should be designed so that through services run through without switching. And this being the US, on a switch onto the end of the branch line (if the branch is to be accessed two-way, this is on the other side of the flyover, not in the main corridor)

So:

  • pull the main line alignment apart to allow a central track;
  • have the switching loop branch off one of the two main lines;
  • have the other main line switch onto that; and
  • fly the switching loop out of the main line corridor.

There is at least one switch on the branch line end, more if its a dual-track line or a t-intersection for access in both directions. If its a two-way Express alignment, then it would have the identical alignment on that end, so four switches total to interconnect the HSR corridor with a two way Express alignment. Add two more switches if a standing loop is required on the interconnection line.


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
by BruceMcF (agila61 at netscape dot net) on Mon Mar 26th, 2007 at 11:12:42 AM EST
[ Parent ]
My focus above is on branch/main line junctions, rather than main/main line junctions

The switches used being high-speed switches, what I posted applies equally for 'branch/main' and 'main/main'. What may have been confusing is that I just didn't draw up the other end where the branch reaches the conventional line, which can be built as a mirror image of the high-speed junction, or simpler, depending on line speed and frequency (and number of tracks). The lots of Italian interconnections mentioned (& photo-documented -- the one shown is the Interconnessione Cassino, at the foot of famed WWII flashpoint Monte Cassino) are such.

For single-track access (which I'd generally advise against -- keept it double-track at least on the acceleration length, or until it connects to the conventional line), yours is fine, except if you fly over only from one side and connect on the other side, the through tracks can remain straight.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Mon Mar 26th, 2007 at 12:00:04 PM EST
[ Parent ]
OK, its the same number of switches, the central access is more space conserving, the two separate flyovers more flexible. Looks like a footprint / cost / frequency tradeoff to me.


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
by BruceMcF (agila61 at netscape dot net) on Mon Mar 26th, 2007 at 12:58:02 PM EST
[ Parent ]

Display:

Top Diaries

Occasional Series