Beautiful Day aint it..

[Khel]

Originally Posted by burn_this_city

The best solution would be to build a Tim Hortons on the corner of every major intersection. So the yuppies can get their coffee every morning, and the cops will be in line of sight in the event of an emergency like this..

You mean there isn't one already?? Who knew...

[Bob]

I'm somewhat surprised that major traffic lights don't have battery backups in them.

[FireFly]

Originally Posted by Bob

I'm somewhat surprised that major traffic lights don't have battery backups in them.

Probably they have none because a battery won't tell them which colour to be at any given time...

[rockstar]

Yes, it is a beautiful day.

[ken0042]

Originally Posted by FireFly

Probably they have none because a battery won't tell them which colour to be at any given time...

How do you figure Firefly? You figure it's impossible to have the control computer on a battery backup?

[Got Miikka?]

I just snowboarded to work this morning, there was more than enough snow. It was kind of like Superman III, where the guy has a ski hill on top of a skyscraper. Except I wasn't on top of a skyscraper. But I WAS downtown.

[V]

Originally Posted by Bob

I'm somewhat surprised that major traffic lights don't have battery backups in them.

I'm also quite surprised they can't work off of battery backup. They use a very small amount of power, and it wouldn't take much to make room for the battery in that control cabinet. There's gotta be a reason, I just don't know what it could be. And I've designed traffic signals.

[FireFly]

Originally Posted by ken0042

How do you figure Firefly? You figure it's impossible to have the control computer on a battery backup?

Nope, but really, how expensive would that be? It's probably not impossible, but probably really difficult to have the lights talk to each other, all on a control computer that is it's own system for that particular set of lights...

In addition, because each set of lights would be on it's own circuit, let's say that downtown goes down... there's nothing to say that the lights would operate consecutively like they normally do, resulting in more stops and starts. Whereas if you have police at them, they can direct in such a fashion that traffic flows smoothly.

If that made any sense.

[ken0042]

Well, I guess it's news to me that any lights in Calgary are synchronized. Put putting that aside for the moment, I'll ask this:

Which is better- lights not working and intersection treated as a 4 way stop? (Or in the case of 114th and Barlow you now have a 16 way stop as there's a total of 16 lanes hitting the intersection) Or would it be better to have the lights operate on some pre-programmed sequence that would allow for traffic to flow?

I mean, the reason we have lights in the first place is they work better than a 4 way stop in high volume situations.

I can see the cost of placing a battery backup system being more per year that what it would cost to pay police salary for the few times the lights go down. But that just brings us back to the question; why don't police direct traffic in times of need?

[FireFly]

Originally Posted by ken0042

Well, I guess it's news to me that any lights in Calgary are synchronized. Put putting that aside for the moment, I'll ask this:

Which is better- lights not working and intersection treated as a 4 way stop? (Or in the case of 114th and Barlow you now have a 16 way stop as there's a total of 16 lanes hitting the intersection) Or would it be better to have the lights operate on some pre-programmed sequence that would allow for traffic to flow?

I mean, the reason we have lights in the first place is they work better than a 4 way stop in high volume situations.

I can see the cost of placing a battery backup system being more per year that what it would cost to pay police salary for the few times the lights go down. But that just brings us back to the question; why don't police direct traffic in times of need?

The ones downtown all are for the one ways. You can go from one end to the other if you are going at the proper speed.

And I'm not saying that having a battery would be worse, I'm saying that the lights still have to talk to the other lights at the same intersection so they know they aren't all green at the same time... and what's going to control that? It isn't just a battery you need....

However, having the cops there would've been the best solution. I don't know why they weren't, I'm just saying having batteries isn't as easy as you think it might be!

[ken0042]

Originally Posted by FireFly

I'm saying that the lights still have to talk to the other lights at the same intersection so they know they aren't all green at the same time... and what's going to control that? It isn't just a battery you need....

Firefly, I think you are misunderstanding us. We aren't talking about just putting in batteries to power just the light bulbs. We are talking about using battery backup for the traffic control device; the grey box that sits beside every controlled intersection and tells the lights what colour to turn. It has a computer inside that runs switches. (I know because for Y2K some cities had to set theirs back to 1972 because they couldn't switchover in time.) And a computer can run on batteries; as can light bulbs.

[FireFly]

Originally Posted by ken0042

Firefly, I think you are misunderstanding us. We aren't talking about just putting in batteries to power just the light bulbs. We are talking about using battery backup for the traffic control device; the grey box that sits beside every controlled intersection and tells the lights what colour to turn. It has a computer inside that runs switches. (I know because for Y2K some cities had to set theirs back to 1972 because they couldn't switchover in time.) And a computer can run on batteries; as can light bulbs.

Oooooh. See I thought it was done centrally. IE, not in a little box. I don't drive, so I don't pay attention to things like this.

[Bob]

Originally Posted by FireFly

Probably they have none because a battery won't tell them which colour to be at any given time...

Well, in a situation such as a power-outage, the lights don't need to talk to other lights, or any central controller, they only need to keep operating on some failsafe program, even if it's not totally appropriate timing, so that traffic can continue flowing. Once power and connectivity has been restored, they can return to their regularly scheduled programming. Since full-blown power outages are rare, and usually don't last for more then a few hours, it would at least help to avoid gridlock, although it's likely only worthwhile for major intersections, and it would be better then turning a major intersection into a four-way stop.

[Nufy]

About half of calgarys intersections are controlled by a central system.

http://content.calgary.ca/CCA/City+H...ement+FAQs.htm

Look for the MIST information...

[V]

Firefly,

Every single intersection is operated by a computer that talks to all of the lights at each intersection. For half the city, as Nufy pointed out, this computer is a computer located at the Manchester building (I think, haven't been there, although I'm planning a visit). For the rest of the city there is a control cabinet at the actual intersection. This control cabinet does a number of things, but one of those things is make sure that the lights in one direction are never green when the lights in the perpendicular direction are green. Now, with the cameras, that control cabinet is even more impressive, and costly. I've been told the higher end computers (we designed for them at the new lights in Chestermere) will put you back about $50,000.

As for the cost to build an entire intersection (mast arms, signals, cameras, control cabinet) it's about $250,000. It gets to be even more when you include advance warning signals.