Wow, this was only a two month project! The crossing signals are from nj International, with logic from Azatrax. My detection is all digitrax bdl168 and bd4 units, so (with fantastic customer support from Azatrax) I had to convert the detection output using optoisolators. The cantilever signal accounted for a good few weeks of the project...brass and styrene (I now know why anyone who sells/plans to sell them charges so much! Very time intensive!). All of my signal control is via digitrax SE8c. Got kind of a funky camera angle...the cantilever section looks a bit distorted in the photo. Would be happy to answer any more technical questions...I know I combed the internet and eventually had to figure most of it out myself. My reason for using he Azatrax board was because I like everything to function without having to plug in the computer. Thanks to all TB members for various past posts on various bits and pieces of information necessary for this to work! [video=youtube;qFY8xRqfglk]http://http://youtu.be/qFY8xRqfglk[/video]
Way cool! Nice effect. BTW, federal law requires something like 27 seconds between the warning and the train. I don't know how long that is in N scale seconds.... Nice work! Regards, Otto K.
Haha! I suppose that would be .16875 seconds in nscale! Really though, I am still working on distances for the detection sections. The near track is the main line, so will require more distance/time. The far track has a low speed limit, so even the train in the video is going a bit fast for that length of track.
Looks great. I went with the Azatrax as well. Used the TeamDigital detectors, to avoid the optoisolators.
20 seconds minimum from the time the lights turn on to when the train hits the first plank of the crossing. 13 seconds minimum from when the gates are all the way down to when the train hits the planks also.
FRA bulb voltage is 85% of rated bulb voltage, 35to65 flashes per minute. I'm having a maintainer flashback!!
Here is a bit more detailed write-up. Again, I will be happy to answer any questions on any particular aspect of the setup...as I was writing I realized this could be a very long article indeed depending upon how and where detail was detailed! View attachment Crossing Gates.pdf
Federal law should be 20 senconds once the gates are fully down, before the train enters the crossing, but most I have been at are longer than that, but I don't think it will mtter to most folks, just be sure your train dose not get to the crossing before the arms are all the way down.
its 20 seconds from when the lights/bell start to when the train gets to the first crossing plank minimum. It is a minimum and the BNSF actually pads the FRA numbers so were always in the safe zone. im sure the other RRs do the same but thats the min. FRA requirement.
How is this actually implemented? In other words, how are contemporary flashers and gates activated by the prototypes? If the speed limit in a block is 30 mph, with one train traveling at 30, and another traveling at say 15mph, would the slower train just trigger the gates and give a longer lead time?
crossings use an AC overlay circuit(except some older stuff like eezer weezer DC stuff) and a GCP(grade crossing predictor) or HXP/PMD watch the overlay for movement within the circuit. The box basically uses an ever changing equation to "predict" when the XR(crossing relay) needs to drop and provide the minimum warning time for the train. It watches the motion of the incoming train and can sense its speed and adjust accordingly. Theres 2 types of sensing. Constant warning and motion detect. constant warning basically drops the XR when it sees any motion and drops when it needs to for the speed of the oncoming train. motion detect basically drops when it first sees anything at all change in the circuit and that could mean 20sec of warning time or 30 no matter what the trains speed may be. Ill just say its a bit complicated. Newer boxes like the GCP 4000 can even give you a rough estimate of train speed. The signal/crossing systems seem like theyd be easy but its anything but that.
