Doug,
Those are what they call top shelf couplers and are "required" on tanks of haz mat. You are correct in that it is designed to keep the adjacent coupler from riding up and out of the coupler of a car equipped with the top shelf coupler. The explosion on the N&W in the early 70's at Decatur, Ill. was caused when 11 car loads of LP gas were allowed to roll free into a track. They gained speed as they rolled since most yards have a slight "bowl" shape with the low part in the middle to facilitate better rolling while switching. They struck a single empty boxcar that was coupled to 50 cars of grain which of course did not move. The force of the coupling caused the empty boxcar to jump up, allowing its' coupler to lift vertically out of the coupler of the adjacent tank car and it was then driven through and punctured the end cap of the tanhk car. The LP gas, loaded under extreme pressure, immediately escaped in to the atmosphere, and since it is heavier than air, and settled like a dense fog over the entire East half of the yard before it was ignited by an unknown source. When it went off, it instantly killed 7 employees, burned and injured 25 others, destroyed 9 locomotives, 952 freight cars and literally wiped out the entire east half of the yard that was 3 miles long and 95 tracks wide, collapsed two schools, damaged or destroyed over 400 houses, injured over 250 citizens, shattered windows in the downtown area 4 miles away and otherwise created quite a stir. Yours truely just happened to be standing nearby, but was leaning against a large concrete bridge pier that was between me and the blast talking to another guy. I felt the blast and heat but was basically protected by the pier. The guy I was talking to was blown over and rolled almost 25 feet with some small cuts and abrasions and a severe "sunburn" from the flash. Just my lucky day I guess as I then got to work 16-18 hours a day for 84 days straight while we continued to try to operate trains in and out and clean up and rebuild at the same time.
As far as you and Marc's derailments, I agree with Pete. I haven't had a derailment in at least a couple of years unless it was something that I caused by not paying attention. I think if you look back you will see that me and Pete have always stressed good track work. A bad spot will always get ya. Maybe only once out of every 10 or 25 laps but it will get ya.. Check for mismatched joints, cross-level, reverse crosslevel, dips and humps, and of course the good old common Atlas turnout.
prof
