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Road Conditions: Grand Avenue at Westbound Arterial

Just because I hadn’t done so for quite a while, I rode Grand Avenue from Beechwood north to the rail trail. The rotted asphalt at the Westbound Arterial (a.k.a. Maple St, at that point) intersection makes it easy to spot the quadrupole sensor loop:

Grand at Arterial WB - front camera - 0193

Grand at Arterial WB – front camera – 0193

After half a minute, with no traffic pulling up behind me, I eased the bike over the central wire:

Grand at Arterial WB - front camera - 1693

Grand at Arterial WB – front camera – 1693

Which is exactly as awkward as it seems:

Grand at Arterial WB - front camera - 1945

Grand at Arterial WB – front camera – 1945

Much to my surprise, the sensor tripped:

Grand at Arterial WB - front camera - 3044

Grand at Arterial WB – front camera – 3044

That’s about 50 s from the time I rolled over the first of the two sensor loops, which is fast enough for me. It’s unusual to find a sensor loop that detects a bike, though.

A bit over 6 s seconds later, I’ve cleared the intersection:

Grand at Arterial WB - front camera - 3445

Grand at Arterial WB – front camera – 3445

The rear camera shows that the light remains green:

Grand at Arterial WB - rear camera - 1085

Grand at Arterial WB – rear camera – 1085

And it stays green:

Grand at Arterial WB - rear camera - 1121

Grand at Arterial WB – rear camera – 1121

About 11 s after turning green, a car approaches the sensor loop:

Grand at Arterial WB - rear camera - 1228

Grand at Arterial WB – rear camera – 1228

I think that reset the signal timing, so that light remained green for nearly 23 s:

Grand at Arterial WB - rear camera - 1581

Grand at Arterial WB – rear camera – 1581

It turned red after 26 s:

Grand at Arterial WB - rear camera - 1671

Grand at Arterial WB – rear camera – 1671

As nearly as I can tell, the minimum green time for this intersection is 12 s.

So life is good: the sensor loop detects a bicycle and the signal remains green for long enough to a bike to clear the intersection. If only all intersections worked that way!

Compare that with the minimum 7 s for the Burnett Blvd intersection and you (well, I) wonder why crossing six lanes requires 5 s less than crossing three lanes. Perhaps different standards apply to this single-direction cross-traffic flow that make it much more difficult than Burnett’s bidirectional cross traffic?

 

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  1. #1 by M Lange (@errorad) on 2016-06-01 - 03:43

    Curious. Where I live, our traffic light sensor loops typically have three yellow dots to show cyclists where the best spot is to trigger them. Honestly, though, judging from your pictures, that kind of thing would require paint on the asphalt to A) Exist, and B) Be visible. Those roads are grotesque.

    That said, I have observed workers testing coils with some form of handheld device and what appears to be an electromagnet on a cable. I’d be curious to know if it was just a hunk of metal on a string, whether he was measuring the output of the loops, or whether there was actual electrical oscillation of the object.

    • #2 by Ed on 2016-06-01 - 09:00

      require paint on the asphalt

      Yeah, and the asphalt under the paint should exist, too. [sigh]

      measuring the output of the loops

      From what I’ve read, a vehicle changes the loop inductance, which then changes the oscillator frequency, so a fast check on the sensor would be to make sure the oscillator is running and driving the loop. No signal = no oscillator.

      Internet lore to the contrary, I doubt that a small transmitter can overdrive a well-built oscillator, particularly at low frequencies.

      • #3 by M Lange (@errorad) on 2016-06-01 - 17:53

        Hm, so probably just a check of the field, then. I’m curious how large of a hunk of iron or steel you would need to more effectively set off the loops given your lack of markings, asphalt, etc.. Obviously it’d be more of a pain to haul around, but may be handy for those loop-trigger-only intersections.

        My biggest pet peeve is currently one intersection with a major road going north/south and a lesser road going east/west. Each has one lane per direction, directions of travel separated by a yellow line, no medians, and north/south each have a left turn lane. Cars turning left coming southbound often hit the westbound loop, triggering the east/west signal, except it then sees once it’s time for a green that there are no cars waiting, so goes right back to giving north/south the green. This is usally seconds before I pull up waiting to go east, of course. (And the light cycle thus resetting the wait timer again, another 15 or 30 seconds depending on time of day).

        The number of times I’ve arrived at the loop as north/south went red, just for them to be given green again is rather high. I can only imagine the frustration of trying to do so on a bicycle. Ugh.

        /rant