Your article today about signal gaps and the Chatsworth collision requires response. The facts about the locations of the signals in the Chatsworth vicinity are clear from your map yet your “experts” draw the wrong conclusions. For the benefit of your readers let me point out:
All of the signals shown on your diagram can display various colors or aspects depending on whether the track ahead is occupied.
As train 111 approached Signal number 2 on your diagram the signal was displaying yellow, which warns the engineer that the next signal is red.
From Chatsworth station the engineer can see signal number 3 on your diagram. As soon as signal number 3 comes into view the engineer’s actions are controlled by that signal, not by the warning from the preceding signal.
Repeater or reminder signals can be very useful on curved track or where the engineer’s line of site is obscured by bridges or tunnels for example. They are not necessary when there is a clear view of the signal along a straight stretch of track with no visual obstructions, as is the case from Chatsworth station north to the signal in question..
No amount of additional signals or trackside warning devices will prevent an accident if the engineer is not looking!
Your contributor Mr. Meshkati says the system is designed “in a haphazard way”. This is not true. The system is designed so that engineers receive sufficient advance warning of a stop signal so that they are able to stop their train before reaching it. In the case of the Chatsworth collision the engineer had in any event stopped at the station in advance of the red signal. He could see that signal from his cab before leaving the station. He was apparently not paying attention. Only an electronic device that automatically applies the brakes before the red signal would have saved that situation.
As we saw at Rialto just recently and at Placentia in 2002, a second engineer in the cab is not the answer. Let’s get on with installing a modern, fail safe, Train Control System.
President, Rail Passenger Association of California
Former Operations Manager, British Railways.