Traffic Measurement box thingy-mo-bober

[Ducay]

Quick question; the city has installed one of those mobile boxes that measures traffic near my house; do these measure the volume of traffic, or volume and speed of traffic?

I'm not concerned about my speed (its almost literally on my driveway), but I need CPs help with me winning (or losing) a debate with the wife

[Frank MetaMusil]

IIRC, the single cable track volume only, and the doubles track speed and volume.

[BlackArcher101]

I think the dual cable ones are used to determine axle types and not speeds, but I might be misinformed.

Warning: If you win the argument, you will lose in so many other ways.

If I were you, I would tell her she's right, even if she's wrong.

[You Need a Thneed]

is it double over two lanes, and single over just one? If so, it's just to measure traffic in each lane separately, I believe.

[ken0042]

How could it measure speed? It would need to know tire size. A Smart car going over it would have a much larger time between hitting the first and second tubes than a full sized pickup.

[octothorp]

Originally Posted by ken0042

How could it measure speed? It would need to know tire size. A Smart car going over it would have a much larger time between hitting the first and second tubes than a full sized pickup.

Nope, it only needs to measure the first of the two 'blips' on each tube, and ignore the second, essentially taking vehicle size out of the equation.

[metallicat]

Can you take a picture of it? We have some here that are little boxes that get drilled into the actual road, and they do calculate speed. It's not for enforcement, obviously.

[Ironhorse]

Originally Posted by oilers_fan

Can you take a picture of it? We have some here that are little boxes that get drilled into the actual road, and they do calculate speed. It's not for enforcement, obviously.

I do wonder if CPS gets to use the data for locating honeypots, er, "enforcement".

[Ducay]

I'll take a picture tomorrow if its still there;

essentially a brown metal shoebox with 2 black lines running across the road; which is just your standard neighborhood street with houses along it (is in a playground zone though)

[Hanni]

Originally Posted by octothorp

Nope, it only needs to measure the first of the two 'blips' on each tube, and ignore the second, essentially taking vehicle size out of the equation.

This is correct.

[Reaper]

Originally Posted by Puxlut

Warning: If you win the argument, you will lose in so many other ways.

If I were you, I would tell her she's right, even if she's wrong.

It is the easiest way. Nothing wrong with picking your battles. It helps you avoid being all tired of arguing when something really difficult comes up.

[sclitheroe]

Originally Posted by octothorp

Nope, it only needs to measure the first of the two 'blips' on each tube, and ignore the second, essentially taking vehicle size out of the equation.

Also, theoretically, if the tube was sensitive enough (say a piezo electric sensor instead of pneumatic, and thus capable of detecting contact instantly), you could simply measure the duration that the tire is on the tube, in microseconds, and get a good idea of how fast a car was going. At 60 KM per hour, if the tube is say 2 cm in diameter, the tire is going to be in contact for about 1200 microseconds.

But they don't do that, because your solution is obviously much simpler.

[Frequitude]

Originally Posted by ken0042

How could it measure speed? It would need to know tire size. A Smart car going over it would have a much larger time between hitting the first and second tubes than a full sized pickup.

Ken, how could you. I'm pretty sure this is the first time you've ever failed the somehow-knows-every-random-fact test on CP.

[Jackpot_Smooth]

Sort of off topic but every so often by market mall, along shaganappi i see a cop at the intersection of shag and 32nd ave, looks like they're wired to the box on the NE corner. anyone know what they're doing when they do that?

[Hanni]

Originally Posted by Jackpot_Smooth

Sort of off topic but every so often by market mall, along shaganappi i see a cop at the intersection of shag and 32nd ave, looks like they're wired to the box on the NE corner. anyone know what they're doing when they do that?

Are red light camera's wired to some sort of network or do they have to download the data to issue tickets?

[Bring_Back_Shantz]

Originally Posted by Jackpot_Smooth

Sort of off topic but every so often by market mall, along shaganappi i see a cop at the intersection of shag and 32nd ave, looks like they're wired to the box on the NE corner. anyone know what they're doing when they do that?

Pretty sure they're just manually controlling the lights.
I've seen them there at Christmas and other high traffic times quite often.

[4X4]

Originally Posted by Bring_Back_Shantz

Pretty sure they're just manually controlling the lights.
I've seen them there at Christmas and other high traffic times quite often.

Interesting. I've wondered from time to time why the police don't sometimes do that. Some intersections just need a human brain controlling them from time to time. For example, the intersection at McLeod and 26th ave. If a train interrupts a SB to EB turn cycle, the intersection is fata'd for about 20 minutes after that. Eating alone at Humptys can sometimes be very interesting.

[Yasa]

Originally Posted by 4X4

Interesting. I've wondered from time to time why the police don't sometimes do that. Some intersections just need a human brain controlling them from time to time. For example, the intersection at McLeod and 26th ave. If a train interrupts a SB to EB turn cycle, the intersection is fata'd for about 20 minutes after that. Eating alone at Humptys can sometimes be very interesting.

The Glenmore/Elbow/5th St to Macleod intersection could benefit from a person monitoring the lights. That whole area is a mess.

[Bill Bumface]

Originally Posted by sclitheroe

Also, theoretically, if the tube was sensitive enough (say a piezo electric sensor instead of pneumatic, and thus capable of detecting contact instantly), you could simply measure the duration that the tire is on the tube, in microseconds, and get a good idea of how fast a car was going. At 60 KM per hour, if the tube is say 2 cm in diameter, the tire is going to be in contact for about 1200 microseconds.

But they don't do that, because your solution is obviously much simpler.

Different tire diameters and running pressures create significantly different sized contact patches, so it would be impossible to measure this way.