How can a signal be missed?

[Railway Man]

I think you meant "Method of Operation" or "train-control system," as TWC and DTC are not signaling systems.

Depends on how many trains you want to run, and if you define "efficient" as "delivers most value for least cost of capital, operation, and maintenance."

For low-train-density railways, TWC and DTC are the most efficient.  There is very little real difference in efficiency between the two.

For high-train-density railways, CTC is the most efficient.

ABS is not a Method of Operation or a train-control system; it's a safety overlay on a TWC or ABS system.  There is some increase in efficiency of operation on a single-track railroad and a significant increase on a double-track railroad, compared to TWC or DTC without ABS.

RWM

 

[Jack_S]

The Metrolink train ran at least two signals in order to end up in this final tragic position.

Mark

 Sorry, but I believe you are wrong on this point.  Based on a detailed map (LA Times, Monday  15 Sept 2008) of the situation, which I have posted about in another message in this thread, he only ran one signal.  I will describe the signal situation again below.

The tracks in the vicinity of the Chatsworth Metrolink station are in a sort of an S-shape.  I am writing from the point of view of a northbound Metrolink train, which would come into the area on a West-North-West heading, on a single track main. 

Just before De Soto AVe. there is a south-facing signal to the right (north) of the single track.  Just after De Soto is the south switch for the siding, which is to the main track's left.  Just past the switch there are 2 signals, 1 on each side of the tracks and facing north. 

Just after the switch, the 2 lines curve north and, after about 1 mile, they are headed due north just south of Lassen St..  Just before Lassen there are 2 signals, one on each side of the tracks, both bi-directional, facing BOTH north and south. 

About 1/4 mile past Lassen there are 2 more  bi-directional signals, also on both sides of the tracks.  This 3rd set of signals is just BEFORE the Chatsworth station.  The station is on the right (east) side of the tracks.

About 1 mile north of the station, is the switch controlling the north end of the siding where it rejoins the single main line.  On the right side (east) of the switch is a south-facing signal.  On the left side (west) of the switch is a north-facing signal. 

About 1/8 mile past these signals and the switch, at Rinaldi St., there is a north-facing signal to the right (east) of the now single track.  The rather sharp curve to the west starts right at this signal and, as the investigation showed, visibility around the curve is quite limited.  It seems to me that this last signal is placed to give a south-bound train a preview of the signal to the west of the switch controlling the north end of the siding.  At any rate it didn't play a part in this accident.

So, after passing the signals at De Soto and Lassen, train 111 came to the station with bi-directional signals on each side of the tracks just before the station.  Obviously, under the situation as it existed then, this signal should have been yellow, allowing 111 to proceed into the station to discharge and receive passengers and wait while the freight proceeded safely down the siding.  And, indeed, according to several witness reports in the LA Times, this was the usual procedure.

After the stop at Chatsworth, the train accelerated to 54 MPH, as if the engineer had forgotten that he had just passed a yellow signal.  Fatigue may have been a factor here, since it can do funny things to your short-term memory.  Distraction by text messaging might have been an issue too, even if he did that only while sitting in a stopped train in the station.

So the only signal he blew was the one at the north switch.  His entry into the station was entirely proper.  After that there was only 1 signal, the one just before the crash.  I question the placement of the signals just south of the station.  Having 2 sets of signals, 1 at Lassen, 1 at the south end of the station 1/4 mile away, seems unnecessarliy redundant.  Wouldn't it be better to have them just north of the station, so that the engineer has them sitting in his view throughout any stops? 

In any case, as soon as the engineer accelerated hard out of Chatsworth, his fate was sealed.  Only a quick recognition, well in advance, of the red signal at the north switch could have saved them.  If he went past the switch by 5 feet and stopped, the freight would have still hit Train 111.  Heavy and headed downhill, the UP crew would have been helpless to prevent it.

Jack 

[DMUinCT]

   Zordoz,

   Your right, if the "Derailer" was still in place the Conrail Diesels would have been put on the ground and the wreck would have been avoided.   As it was, just a Penalty Stop was made and the engines drifted into the Amtrak Main.

    Today in the Northeast Corridor, Double Red on a Draw Bridge Approach, the "derailer" is done by opening up the rail.     Note the right rail as photographed from the cab of an Acela.

   

[wabash1]

Rode ACE today san Jose - Stockton. Sunny day outside Tracy encountered a SP tri signal showing approach and at about 600 ft spotted yellow signal as the engineer slowed at that time approach speed. Next signal about two miles showed stop which I could only tell about 500 ft from signal. Stopped and proceeded at restricted speed, think I saw code line down causing red signal. Next signals green- new LED type which could tell 2500 ft away. Take it for what its worth guys.  

so your saying that you saw the led signal a half mile away? what was wrong with the other signal that you only saw it at 500 ft away or in railroad terms 10 cars away,  seems to me if you only saw the signal indication at 500 ft ( 10 cars) then you didnt even see the signal mast or signal box or even the area this signal was protecting.

[CSSHEGEWISCH]

I don't know how things are elsewhere, but I have rarely to never seen derails as part of the protection at an interlocking except at movable bridges.

[blue streak 1]

the only difference was I was looking through two panes of glass not one that the engineer was looking through. I believe the sun was causing some of those sight problems but the angle was the same on that streach of straight track. The weather was clear and visibility unlimited.

[wabash1]

all i am saying is that i can see standard signals 1/2 mile away  clear and approach and on some i can see the restricting and also the stops on others depending on aiming its harder but after a yellow im always going slow so i can stop.. on the LeD signals its about the same just alittle clearer stop signals still look the same.