Starting light working group

[walterclark]

Random thoughts on alternate support.

3 legged chair with light sitting on seat/cradle. Front 2 legs create a relatively wide base with one leg adjustable to eliminate side to side tilt on uneven surfaces. Open frame cradle with "seat" portion connecting from front legs to single vertical spine. Light sits on open seat and has single thumbscrew to spine to secure it. Single rear leg that is hinged to top of spine allowing triangular base angle to be changed for terrain and collapsed for storage. Rear leg length adjustable for tilt and terrain. Cradle tilt angle from rear leg adjustment when in use 0 degrees to 7 degrees tilt back. A totaled Ez-Up (the good ones not the is-this-metal-and-how-could-they-make-it-for-$50 models) could be the material source and that would eliminate the need to fabricate adjustable legs...

Another. A hand on a telescoping arm that could reach from somewhere on the top-holding tripod design to stabilize the light and push the back of it to an angle needed to be seen properly... That range would be up to 4" at the bottom of the light for a 7 degree angle, less further up.

[jkale]

Random thoughts on alternate support.

3 legged chair with light sitting on seat/cradle. Front 2 legs create a relatively wide base with one leg adjustable to eliminate side to side tilt on uneven surfaces. Open frame cradle with "seat" portion connecting from front legs to single vertical spine. Light sits on open seat and has single thumbscrew to spine to secure it. Single rear leg that is hinged to top of spine allowing triangular base angle to be changed for terrain and collapsed for storage. Rear leg length adjustable for tilt and terrain. Cradle tilt angle from rear leg adjustment when in use 0 degrees to 7 degrees tilt back. A totaled Ez-Up (the good ones not the is-this-metal-and-how-could-they-make-it-for-$50 models) could be the material source and that would eliminate the need to fabricate adjustable legs...

Another. A hand on a telescoping arm that could reach from somewhere on the top-holding tripod design to stabilize the light and push the back of it to an angle needed to be seen properly... That range would be up to 4" at the bottom of the light for a 7 degree angle, less further up.

I like your first idea. Sitting the light on a seat will keep the weight low, and we could still use the eye-bolt to attach a telescoping arm for proper tilt angle..

[walterclark]

I finished modifying Kevins finish box to include the start tone decoder - it interfaces the finish electric eye, manual start/stop switches, PC and now the start tone decoder to each other. I also got a copy of the timing software from Kevin so I could try out the whole system (across a 50' "wire"). I am happy to report that it all works GREAT!...At least over the short wire I have on my basement electronic bench.

Since I have the KSCC wire here for maintenance I plan to connect the timing system to either end and check the tone transmission over its distance this next week.

Joey - once you settle on a design for the stand I need to know how long a wire I would need to be able to run it from the bottom of the traffic light to the ground near one of the front legs. If the light hangs it will need to be long enough to got from the bottom of the light up to the eye and back down. If the light sits on a cradle, it can probably go straight down. This will be how long I need to make the 8 conductor cable that goes from the traffic light to a small box at the bottom of one of the legs where battery power, start switch electric eye and comm wire connections will be made.

[jkale]

It will be a stand that the light sits on.

How far away from the driver are we planning on putting the light? That determines how far off the ground the bottom of the light will be...

[walterclark]

When I was doing my observations of the light patterns yesterday I sat 15' away from the light. That is about as close as I would imagine positioning it, and the starters switch is on a 25' cord so a bit less than that would be the upper limit.

I am not sue I understand the relationship between height and distance, if we tilt the light so it is parallel to the road.

I would suggest a couple things. First, that we assume the traffic light is mounted so the beams are parallel to the road. Second, we pick the point on the traffic light midway between the green and yellow lights as the point we want to be even with the "drivers eye" height. Third, we figure out what the average "drivers eye" height is and use that value for designing the stand with the first and second points in mind.

Anyone want to guess the height of Bob's and Butch's eyes from the road? That should get us to the extreme cases. I am around 40" in my car.

[jkale]

I am not sue I understand the relationship between height and distance, if we tilt the light so it is parallel to the road.

I was just thinking that the farther away from the driver that we position the light, the closer to the ground we will want it..

[DaveVT02S]

Would it be possible to rotate the lens 180 degrees to change the beam angle to 7 degrees up? (the K.I.S.S. principle)
Thinking it would keep the stand smaller and more stable?
(2 cents)

[walterclark]

Interesting idea, but the sun shades are also sloped and not really adjustable. So they would block a portion of the lights if the LED lights are rotated so they tilted the beams up and then the light was mounted lower and the light assembly set perpendicular to the road as you described. Tilting the whole thing back to keep it low (compared to a normal traffic light) tilts the shades up so they are not blocking the lights themselves but still reduces sun and sky glare. Also, we need to make sure we dont put the light so low that someone cant see parts of it because their hood blocks it, or so high that it is blocked by the cage halo or top of the windshield (or for that matter so far off the the side that it lines up with a lot of A-pillars and A-pillar cage bars).


By the way (for everyone reading) I have assumed all along that everything regarding tilt is relative to the road surface and the location of the light is at the same elevation as the road next to it. The road may or may not be at an angle other than level, but should be constant in the area of the start, and the car and driver will also sit relative to the road surface. So however high or low the lights ends up they will appear the same out the front of a car at each hill. If we had a location where the light had to sit several inches down from the nearest road surface, along the side of the road (I dont think that is an issue right now), we would need to figure out how to accommodate that.

[walterclark]

from General Discussions and jkale:

How bright are these LED's compared to the new street light LED's?

1' off the ground 15' away is pretty much what I had in mind...

They are the current GE RX11 8" traffic lights. On axis they are very bright, I would say about the same as most new traffic lights. As I indicated earlier they have a limited vertical beam where they remain very bright and and the lights have an inherent 7 degree downward beam tilt.

The geometry for positioning the light gets more complicated if we mount it very low. In addition to having some range of eye height for drivers that needs to be considered, now we have to also consider their eyes' distance from the start line, which will vary from car to car and driver to driver. Sitting back in a long hooded Camaro with the nose of the car at the start line positions the drivers eyes much lower relative to the center of a rising beam of light than someone in say an original Mini. If, on the other hand, the center of the light beams are set to be parallel with the road, the distance of the drivers eye from the start line does not matter, only their eye height.

One way we can set the traffic lower lower and maintain a beam set parallel to the road and about at drivers eye height for the green and yellow is to invert the lamps in the traffic light. Since the red light has no effect on a driver (it will come on only if they jump the start, and requires no action or change on the drivers part) it would be OK, though not ideal, if that particular light was not seen coming on by the starting driver. So if I reverse the light order in the unit, green at the top, yellow in the middle, red at the bottom, we can lower the assembly about 10" while keeping the yellow and green beams level and at eye height.

In practical terms, lets say we find the average eye height is 36"". To set the mid-line between green and yellow lights at 36" with the present light order (red on top), we would need to set the traffic light on 26" legs. By inverting the lights, we could set it on 16" legs. In both cases the light needs a 7 degree tilt back to maintain a set of beams that are parallel with the road so eye distance form the light does not matter.

Since I mentioned the red light I should mention that Kevin and I do not envision setting the photoswitch so close to the start line that it can be used as a sort of staging light. That is because in order to be sure an early jump start is seen by the starter, the light once tripped, stays tripped for several seconds. So driving onto it then rolling back until it goes out is not a practical use. Thus we see the photoswitch being set a short distance in front of the start line and is generally only tripped by a car well past start during the countdown. I am not sure what "short distance" and "well past" mean yet but I would guess not less than a foot or more than three. Also, there is no audible tone (on the comm wire headsets and speakers) associated with the red light in the current code. It is possible as a future addition.

[DaveEstey]

Just throwing in something I haven't seen proposed. What about mounting the light horizontally rather than vertically?