Cross post: Why don't red lights function as alternate stop signs?

Started by wanderer2575, August 25, 2018, 03:39:29 PM

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fillup420

Quote from: wanderer2575 on August 25, 2018, 03:39:29 PM
I came across this thread on the Straight Dope Message Board.  Link to that thread:
https://boards.straightdope.com/sdmb/showthread.php?threadid=860748

Quote
My son asked me this question the other day and I don't have an answer...  His idea is that a guy facing a red light should have the same rules as a guy facing a stop sign (or blinking red light):  Come to a full stop.  If no perpendicular traffic, then proceed.  The driver from the perpendicular road has the right-of-way.  But the actual rules are of course that a driver cannot proceed through a red light regardless of whether there's any traffic at all from the other direction.  Why is that?

I'm guessing that red lights are generally installed at intersections where it's relatively uncommon for there to be no traffic from the other direction.  But this is very far from uniformly the case, and especially at off-peak hours it's very common for cars to sit waiting for the light to turn green with nothing at all from the other direction.  This seems enormously inefficient.

I can dream up various scenarios where allowing this could cause an accident.  (Perhaps the people will misjudge how far away the traffic is?  Perhaps the second car will be tempted to proceed through without coming to a complete stop?)  But all seem very far-fetched.

I've never thought about that before but it seems like a good question.  If one comes out of a non-signalized crossroad or driveway, one may proceed right, left, or straight through the intersection when one feels it's safe.  But if one comes out at a signal, one has to wait for the green light (permitted turns on red excepted, of course).  Why?

Yes, I've considered that many signalized intersections are limited-visibility.  But yet, one may legally proceed at will through a non-signalized intersection that may be just a hundred feet away from the signalized one.  Visibility isn't any better.

A solution i have thought of would work something like this:

Lets say there is a signalized intersection with lower average traffic, and visibility is good. The default signals would be flashing red (meaning stop and proceed if clear) for the secondary road, and green for the primary road. If oncoming traffic is detected on the primary road, the secondary signals would go solid red. If a car sits waiting for too long, a green would be given for the secondary road.

This allows for entering traffic to not waste time waiting if the coast is clear, or if there is too much traffic to enter.


kalvado

Quote from: fillup420 on September 09, 2018, 08:32:29 PM

A solution i have thought of would work something like this:

Lets say there is a signalized intersection with lower average traffic, and visibility is good. The default signals would be flashing red (meaning stop and proceed if clear) for the secondary road, and green for the primary road. If oncoming traffic is detected on the primary road, the secondary signals would go solid red. If a car sits waiting for too long, a green would be given for the secondary road.

This allows for entering traffic to not waste time waiting if the coast is clear, or if there is too much traffic to enter.
I suspect that for such mode to actually work, traffic flow would need to be very low. If you're talking about larger intersections with multiple lanes, cars spend more time within the box just due to dimensions, and flow would need to be really low, maybe 100-200 vph. The same intersection can handle 4-5k vph daytime (3 lane approaches), so you're talking 2-5% throughput. On a real major intersection that can be only a relatively short period of time with not many vehicles affected. Besides, drivers are likely to be less efficient at 3 AM (that is when the traffic is low) and more likely to make an accident causing mistake with lax control system.

UCFKnights

Quote from: kalvado on September 09, 2018, 10:11:08 PM
Quote from: fillup420 on September 09, 2018, 08:32:29 PM

A solution i have thought of would work something like this:

Lets say there is a signalized intersection with lower average traffic, and visibility is good. The default signals would be flashing red (meaning stop and proceed if clear) for the secondary road, and green for the primary road. If oncoming traffic is detected on the primary road, the secondary signals would go solid red. If a car sits waiting for too long, a green would be given for the secondary road.

This allows for entering traffic to not waste time waiting if the coast is clear, or if there is too much traffic to enter.
I suspect that for such mode to actually work, traffic flow would need to be very low. If you're talking about larger intersections with multiple lanes, cars spend more time within the box just due to dimensions, and flow would need to be really low, maybe 100-200 vph. The same intersection can handle 4-5k vph daytime (3 lane approaches), so you're talking 2-5% throughput. On a real major intersection that can be only a relatively short period of time with not many vehicles affected. Besides, drivers are likely to be less efficient at 3 AM (that is when the traffic is low) and more likely to make an accident causing mistake with lax control system.
So is there any data on this? I know that about 10-20 years, the flash at night/inactive signals seem to have disappeared, so we have a before and after on a pretty widespread basis. Has this actually increased safety by any margin?

jeffandnicole

Quote from: fillup420 on September 09, 2018, 08:32:29 PM

A solution i have thought of would work something like this:

Lets say there is a signalized intersection with lower average traffic, and visibility is good. The default signals would be flashing red (meaning stop and proceed if clear) for the secondary road, and green for the primary road. If oncoming traffic is detected on the primary road, the secondary signals would go solid red. If a car sits waiting for too long, a green would be given for the secondary road.

This allows for entering traffic to not waste time waiting if the coast is clear, or if there is too much traffic to enter.

Delaware has done this in the past; the only exception being the green was a flashing green.

The experiment, while lasting many years, evidently didn't work. Basically, those at the flashing red were proceeding when it wasn't safe enough. I don't think any still exist in the state.

ipeters61

Quote from: jeffandnicole on September 09, 2018, 10:32:18 PM
Quote from: fillup420 on September 09, 2018, 08:32:29 PM

A solution i have thought of would work something like this:

Lets say there is a signalized intersection with lower average traffic, and visibility is good. The default signals would be flashing red (meaning stop and proceed if clear) for the secondary road, and green for the primary road. If oncoming traffic is detected on the primary road, the secondary signals would go solid red. If a car sits waiting for too long, a green would be given for the secondary road.

This allows for entering traffic to not waste time waiting if the coast is clear, or if there is too much traffic to enter.

Delaware has done this in the past; the only exception being the green was a flashing green.

The experiment, while lasting many years, evidently didn't work. Basically, those at the flashing red were proceeding when it wasn't safe enough. I don't think any still exist in the state.
As far as I know, there are none.  The only types of constant greens are the ones at the Florida T intersections (I think there's one on Kirkwood Highway somewhere, just can't remember the exact intersection).

I can say that stop signs are an issue in rural portions of Delaware...sometimes people roll through, sometimes people just go at the wrong time.
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