NO caboose? WOW,I woulda thought that woulda been a no brainer with a Steam engine pulling?
Forgive my ignorance but is the desiel there just in case of a problem or? Also looked to be going kinda slow? I guess for photo graphs?
There were two diesels when I watched it on Cajon Pass, and they were pulling, though not in Run 8. That is a Heavy train! And it is my understanding that Big Boy is limited to something like 2/3 power burning oil instead of coal. No caboose on a passenger train. They have that beautiful observation car back there!
1. They've had way too many close calls with BB 4014 and stupid people who want to stand on the tracks.
2. BB is operating off home territory. Some of these bridges are not really designed to support her massive weight. They crawl over them as to not shake the bridge apart.
3. BB has been fitted with 1 oil burner instead of the SP design of two burners to the fire box. She is limited to 2/3 her rated HP currently. SP 4-8-8-2 types had two burners.
4. Diesel is for dynamic braking, further assistance on hills. The diesel is fitted with the electronics to pick up the safety and signaling system signals that are fed from sensors along the track. PTC being the latest such setup. The steam locomotive is not currently fitted with this high tech gadgetry.
In addition to dynamic brakes and track safety equipment interactions, the diesel also helps stretch supplies of fuel and water on long runs between stops. They can set the steamer to be cruising along on point making only a token effort, and the diesel behind it taking the brunt of the load. Like so it helps them reach the next workshop where they can fill the water tanks again, as most of the water stops from the age of steam are long gone.
I was under the impression that UP was asking the FRA on behalf of preserved steam in general to grant an exemption to PTC requirements for heritage steam that isn't in regular revenue service. Usually when the big engines are on the move they have 2-3x their traditional crew aboard, more crew and railfans trackside and aboard the train, and they take extra precautions for line security and track safety. Having the extra crew should make the scenarios that PTC is intended to prevent far less likely to begin with.
Similarly, the bulk of PTC's functions could be implemented on a steam locomotive except one key feature- the ability to disengage the throttle automatically in conditions that would result in an emergency stop. Most steam locomotives would require significant mechanical alterations to be able to accomplish that, although I keep thinking a magnetic breakaway and spring to disconnect the lever and shut the throttle might make it possible with minimal visible changes. I'm visualizing a device that somewhat resembles a car's spring and shock absorber that can be installed in the throttle rod in an out of sight place. In normal use the spring is compressed and the rod latched. Under a PTC throttle disengage, the rod is unlatched and the spring extends, shutting the throttle regardless of where the engineer has the lever. Once the fault is cleared it can be reconnected by shutting the throttle fully, compressing the spring again and allowing the latch to pick back up. A little magnetic trip would be enough to release the latch on computer control.