I know that ATSF F units for passenger service had an oscillating light fitted above the standard headlight. I even found information on how it was developed. What I have not found is the reason for it.
What was the purpose for them?
Here’s a primer:
https://www.american-rails.com/mars.html
Considerably more here although this site could use a little TLC in the format department:
http://www.trainweb.org/gyra/mars.htm
ATSF_mars by Edmund, on Flickr
As automobile use grew and train speeds increased there was cause for concern raised about grade crossing accident frequency and magnitude.
Part of the remedy was the push to design retracting couplers and ‘deflecting’ styled pilots. Then there was attention given to whistles and horns. It was found that some people could not hear certain frequency sounds well so multi-chime horns began to replace the single note ‘blat’ horns.
Finally visibility became an increasing solution with reflective ‘conspicuity’ striping and added front-end lights to raise awareness to an oncoming train. Various styles of animated lights were developed and tested with varying degrees of results.
Today the alternating ‘ditch-light’ is about all that is left of the lighting efforts. It is reasoned that the ‘triangulation’ of the two ditch lights along with the headlight is supposed to give a person better awareness of the speed and distance of the approaching potential for danger.
Some roads used the red colored oscillating light as a warning to approaching trains from the front and/or rear. These lights generally activated automatically upon an emergency application of the brakes with the assumption that the train had parted and is possibly fouling an adjoining track.
[url=https://flic.kr/p/2mphZPT][img]https://l
Thanks. I suspected that it was safety/visibility related but I wasn’t sure how much an oscillating light mounted over a fixed headlight would be of benefit.
See the difference between the Gyralight and Mars-light patterns.
When used as crosding-approach warnings, the idea was that the moving or intermittently flashing beam would attract notice more readily than just a bright headlight. When early streamliners were developed, oscillating lights were tried pointing straight up (the idea being to make a moving beam in the sky or on the clouds, like spotlights at a Hollywood premiere) or at a 45-degree vertical angle (see early C&NW high-speed power as used on the 400). These did not work as well as a light that shone directly to vision and moved in an interesting pattern (something the Mars light does particularly well!)
Note that the ATSF light pictured has one clear and one red lens. The brake-warning lights on, for example, UP and Milwaukee had red lenses in front of the oscillating mechanism, probably do as to be clearly visible but not dazzling to oncoming engineers.
Not sure about Santa Fe’s early E and F units, but on many railroad’s first EMD passenger units the upper light was the regular headlight (as it would be on an engine with just one headlight*) and the lower light in the door was the Mars or other moving light. In a few years, railroads generally found it worked better to have the regular headlight lower, so moved it there and had the Mars light in the upper.
*Note that some railroads (CN, NYC, Pennsy) used just the one main headlight on both freight and passenger units.
One of the BP-20s famously had two headlights (and looked somewhat strange as a result to those used to Sharknose esthetics) – it was good enough that they kept it, but not good enough to repeat on other power.
In addition to two EP22s 5700 and 5701:
http://www.rrpicturearchives.net/showPicture.aspx?id=4044142
I run the 5700 on my layout. I like Mars lights [8D]
Word has it that PRR was desperate to get their hands on any available E8s EMD had to offer and two happened to be nearly complete but you’ll have to take them with the extra headlight.
Over the years PRR plated them over or at least removed the guts and left the glass in place. Amtrak is said to have restored the Mars light on at least one of them.
Here’s the BP20 5771:
http://www.rrpicturearchives.net/showPicture.aspx?id=4965563
Regards, Ed
Nice photoshopping
Which one?
Can you be just a bit more specific?
[:^)]
Ed
Keep in mind that the oscillating light will appear to flash on-and-off quite brightly, and flashing lights attract human attention (and in other breaking news, water is wet).
Aaron
A fun “urban legend” I remember coming across was that the lights were called “Mars lights” because back in 1938 during the famous broadcast of “War of the Worlds” on radio, people saw the then-new flashing / rotating lights off in the distance and thought they were Martian spaceships landing.
[alien]
And here I thought the urban legend was that the guy who founded the company was an heir of the Mars candy company and that’s how he got the development capital to make them.
Well, if I was standing on some track and saw a light coming towards me I would move. It wouldn’t matter if it was steady or flashing.
I don’t have any immediate cites, but there are a number of reasons a steady light is not as good as an ‘oscillating’ one. Much of the time there is limited sight distance at a crossing, so there is little or no evident motion parallax to show that the light source is moving, and in fact a headlight can be easily confused with a sun reflection. Meanwhile, the brighter the light, the more difficult it is to assess both distance to it and whatever closing speed it may be approaching with. This is at the heart of much of the Operation Lifesaver PSA message that trains are closer than they appear.
An oscillating light may do the same as the alternately-flashing ditch lights in giving a signal that a train is actively under way or expected to be. The issue then arises that a bright and highly-focused headamp beam can be dazzling if it is rotated or deflected into a driver’s or pedestrian’s line of sight, particularly at night where night vision acuity is ruined and ‘situational awareness’ confused beyond what a distinctive pattern at lower spot intensity would provide.
It’s amusing to see what some of the earliest assumptions about high-speed warning lights were. Some of the earliest involved putting gyra-lite style rotating beams in the cab roof, under t