My landlord and good friend is chair of the Pigeon Key Association. There is a two mile long one lane private bridge out to the key from the main highway (If you seen the movie "True Lies - Arnold Schwarzenegger" you seen the bridge)
Presently, they allow traffic going out for the first 1/2 of the hour and traffic going in for the last 1/2 of the hour. They are looking for a traffic signal on each end of the bridge that would be green unless there is oncoming traffic.
I googled for a few places and sent Emails with no luck so far. Does anyone know of a commercial company that could provide something like this? This has to professional - its for hauling the public to and from the attraction.
Did you check with Crouse-Hinds? I'll bet they have already done this exact system many times. They may even have a radio system so you don't have to run 2 miles of wire. If you don't know the name, look at the nearest traffic light to your house. It will almost certainly have been made by them. They do all sorts of custom systems to handle drawbridgs, etc. This is the base company
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they must have the traffic signals somewhere else.
I was going to suggest the same company- they are located in Syracuse, NY- about 20 minutes from my house. I'm not sure how much longer they'll be here- the parking lot is mighty empty and I've heard the plant has less than 20 workers.
I'd talk to the local town or state highway department - ask advice - they might have an old manual or relay one in junk - when they use solid state models now.
Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
Have your friend contact the State Traffic Engineer in Tallahassee. That office will know which vendors and suppliers of traffic control equipment are currently considered viable. They will presumably also be able to offer some advice on how to approach the problem. It's not as simple as it might appear, but traffic engineers understand the issues involved.
About any programmable four-phase or eight-phase actuated controller could do this job. (This is only a two-phase situation, but there's about no market for twophase controllers.) This is an unusual situation for an actuated controller because of the rather long clearance interval involved.
Issues to ask about:
Would an actuated control really work better than a fixed-time controller in this situation.
Might a TOD/DOW programmable fixed-time controller work better than present setup and/or an actuated controller
Recommended controller vendors and models. Preferred vendors in FL may be different than those preferred in regions with fewer lightning strikes per year.
Recommended loop sensor vendors and models
Should queue length sensing be provided on one or both ends
Recommendations for programming permissive phase timing as fns of elapsed time in a permitted phase, time since last actuation, queue lengths, etc etc.
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I am not a traffic engineer, but I designed traffic controllers and worked with traffic engineers (including those in Tallahassee and Dade County), once upon a time.
Traffic engineers in general were panned recently on this NG. It's like anything else: some are better and more motivated than others. Some are genius good at tuning an intersection or stretch of arterial to run smoothly with max volume and minimum delay. It ain't as simple as it might appear. There are well over a hundred user-adjustable variables in a fully-actuated 8-phase dual ring controller. Things may (or may not) have progressed now to the point where controllers employ AI and/or neural net logic to learn from experience. I doubt that they have because it's a very cost-competitive meet-the-spec low-bidder-win biz that doesn't motivate R&D beyond cost reduction in design and mfg.
Sounds to me like something homebrew is needed - they might make something, but it's not going to be setup for that long a span between the ends. They might make something to control a 100' tunnel, not two miles.
Free-form idea dump - see if you can find any gems here.
To be really reliable, this needs to be preferably a wired system between the two ends - an RF link would work, but it increases the possible failure modes. Is there any communications cable or a vacant conduit between the two points, preferably a telephone cable where you can lease a few pairs?
It needs to have some 'smarts' and feedback between the two signal light control stations at the ends. The system HAS to handshake every status change between the two ends - you don't want it going green at both ends.
And to keep track of the traffic if it's operating totally "automagically" you might want those comm pairs available at a few spots mid-span (along with a power source) so the electronics can track the progress of the traffic with loop detectors, treadle switches, or other means. (Optoelectronics is out due to fog and birds.) You would count five vehicles entering the span, five at the first mid-span check, three at the second mid-span check, three clear the other end - hey, waitaminit...
A simple timed system is out, too easy for someone to stop along the way. (Even if there are signs every 100 feet warning people not to stop, some moron will.)
My vote would have two sets of off-the-shelf access control systems and motorized gate arms at both ends, and multiple cars get a short window (5 minutes) to get on as a batch, then it's the other direction's turn. Call Stanley and see if they have parts you can use to kit-bash into what you need.
Use a 'check code' system using off-the-shelf parking lot access control equipment and some custom smarts to run them. They sell these automated systems where the ticket reader reads the IN time on the ticket and computes the payment - that IN time could just as easily be a sequential serial number with a check digit.
People receive a code (ticket printer/spitter) to raise the arm and get onto the bridge, and at the other end they enter the same code (keypad or put the machine-readable ticket into a ticket receiver/ reader) to raise the exit gate arm and clear them across in the computer. When all the vehicles in that direction's batch are confirmed clear, allow the opposing flow. And if nobody's waiting, go to 'first car either way gets the priority'. That can get goofed up too, but it's less likely.
And you can have all the disclaimer crud printed on the back of the ticket with the bridge rules (This Ticket Limits Our Liability...) so they can't say you didn't warn them. ;-P
You may want an override so the local LEO or Fire/Ambulance officials can override the timer and get priority the second the last car clears. Or better, some sort of 'secret' control access phone number so the police or ambulance dispatcher can preempt the bridge timing the second the call goes out, and the green will be waiting for the ambulance when they arrive.
Brian Lawson wrote in news: snipped-for-privacy@4ax.com:
I've replied to Karl. With a few ideas. Without knowing exactly the use, WHO uses it (public or employees?) the proposed budget, and potential liability issues, its a tough call.
BTW. Crouse Hinds hasn't made traffic signal equipment in years. :-) An old CH rep relocated and dropped by our shop and gave me a brand new CH signal head with ball cap visors. Pretty cool looking, it sits up on a shelf in the shop.
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