Comments on: red light green light http://dan.hersam.com/2003/10/28/red-light-green-light/ A computer programmer's commentary on news, Linux, programming, music, web design, trivia, humor, usability and whatever else strikes his fancy at the time. Thu, 24 Jul 2008 14:58:43 +0000 http://wordpress.org/?v=2.6 By: jason http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2628 jason Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2628 I've never heard the flashing lights thing. That would be cool if it worked. As for the U-turn turn-right trick, it drives me crazy when I see people doing it, and I've seen people pulled over for it too. The other one is turning right at a light when that lane is totally full. Some people will cut through a business parking lot, usually a 7-11 and jump ahead of the people who are in the turning lane. I’ve never heard the flashing lights thing. That would be cool if it worked. As for the U-turn turn-right trick, it drives me crazy when I see people doing it, and I’ve seen people pulled over for it too. The other one is turning right at a light when that lane is totally full. Some people will cut through a business parking lot, usually a 7-11 and jump ahead of the people who are in the turning lane.

]]> By: Cameron http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2629 Cameron Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2629 I think the flashing trick does work, but it depends on whether or not the lights are intelligent and at what hour of the day/night. Many lights in Provo are light detecting, and while I can't give you a quantitative number of flashes needed or operation hours, I often flash my lights if no one is around. Depending on the light, and whether a default minimum time limit has been reached, it quickly changes to yellow. In fact the stoplight north of where we work, on the frontage road behaves that way too. I think the flashing trick does work, but it depends on whether or not the lights are intelligent and at what hour of the day/night. Many lights in Provo are light detecting, and while I can’t give you a quantitative number of flashes needed or operation hours, I often flash my lights if no one is around. Depending on the light, and whether a default minimum time limit has been reached, it quickly changes to yellow. In fact the stoplight north of where we work, on the frontage road behaves that way too.

]]> By: Jan http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2630 Jan Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2630 Police and ambulance services have those green light remotes here. Of course, very few municipalities have upgraded their traffic lights so that the police can actually use them. I've never heard of the flashing headlights at traffic lights before. If it's not a hoax, then it's not something that's used in the southeast. Or at least, it's not something included in the GDOT spec books for intersection lights. Around here, GDOT uses magnometers to sense when cars approach intersections. When the magnometers sense a car it sends a signal to a networked computer, which in turn signals the traffic lights to turn accordingly. If the municipality doesn't want to pay for magnometers, the lights can be timed pretty effectively based on traffic studies of the intersection. You wouldn't believe how accurate and efficient the timing sequences are if they're done right. Police and ambulance services have those green light remotes here. Of course, very few municipalities have upgraded their traffic lights so that the police can actually use them.

I’ve never heard of the flashing headlights at traffic lights before. If it’s not a hoax, then it’s not something that’s used in the southeast. Or at least, it’s not something included in the GDOT spec books for intersection lights. Around here, GDOT uses magnometers to sense when cars approach intersections. When the magnometers sense a car it sends a signal to a networked computer, which in turn signals the traffic lights to turn accordingly.

If the municipality doesn’t want to pay for magnometers, the lights can be timed pretty effectively based on traffic studies of the intersection. You wouldn’t believe how accurate and efficient the timing sequences are if they’re done right.

]]> By: dan http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2631 dan Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2631 Jan: That's interesting. How do the magnometers work? When I had my motorcycle I couldn't get the lights to change until a car showed up, so I assumed it was due to weight. I don't think Utah does their timing sequences right, because at two in the morning, you still have to wait for lights to change. Back in New Hampshire they would just turn the main road to a blinking yellow and the other way to a blinking red. It made life much easier. Jan: That’s interesting. How do the magnometers work? When I had my motorcycle I couldn’t get the lights to change until a car showed up, so I assumed it was due to weight.

I don’t think Utah does their timing sequences right, because at two in the morning, you still have to wait for lights to change. Back in New Hampshire they would just turn the main road to a blinking yellow and the other way to a blinking red. It made life much easier.

]]> By: jason http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2632 jason Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2632 I think you're both correct. This <a href="http://www.dot.state.oh.us/spec/732.htm">document</a> has all the specifications for optical intersection signals, including the <strong>magnetometer</strong>. I think it's embedded in the pavement where the cars stop and maybe it detects the magnetic field of the car. With that it would make sense that your motorcycle wouldn't be detected. Bangerter Highway's intersections are definately not timed. I think you’re both correct. This document has all the specifications for optical intersection signals, including the magnetometer. I think it’s embedded in the pavement where the cars stop and maybe it detects the magnetic field of the car. With that it would make sense that your motorcycle wouldn’t be detected.
Bangerter Highway’s intersections are definately not timed.

]]> By: dan http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2633 dan Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2633 I wonder if the optical sensors are sensitive enough to pick up a motorcycle. You'd think the engineers would take motorcycles into account during their design process. I wonder if the optical sensors are sensitive enough to pick up a motorcycle. You’d think the engineers would take motorcycles into account during their design process.

]]> By: Jan http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2634 Jan Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2634 In Georgia, legislators are considering letting motorcycles turn left on red arrows, etc because the magnometers (that's what GDOT calls them) don't pick up motorcycles. The problem with motorcycles is that the magnometer equipment needed to 'sense' them is very expensive. Also, there's a problem with pavement depth. Magnometers are under a couple of inches of pavement; This makes them less sensitive. In places where there's a lot of snow and rain, they have to be buried even deeper. I hate to tell you this, but roads aren't designed for motorcycles at all. They're not designed for small cars, either. Roads are designed for medium sized trucks, which is the design vehicle size determined by AASHTO. Also, and this is something I've always thought was a little funny, roads are only designed so that 85% of people can drive them safely. That means that we design them so that 15% of the cars on them will have an accident. In Georgia, legislators are considering letting motorcycles turn left on red arrows, etc because the magnometers (that’s what GDOT calls them) don’t pick up motorcycles. The problem with motorcycles is that the magnometer equipment needed to ’sense’ them is very expensive. Also, there’s a problem with pavement depth. Magnometers are under a couple of inches of pavement; This makes them less sensitive. In places where there’s a lot of snow and rain, they have to be buried even deeper.

I hate to tell you this, but roads aren’t designed for motorcycles at all. They’re not designed for small cars, either. Roads are designed for medium sized trucks, which is the design vehicle size determined by AASHTO. Also, and this is something I’ve always thought was a little funny, roads are only designed so that 85% of people can drive them safely. That means that we design them so that 15% of the cars on them will have an accident.

]]> By: dan http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2635 dan Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2635 How rude of them, both for not designing for motorcycles, and for only having an 85% safety design. I'm not impressed. How rude of them, both for not designing for motorcycles, and for only having an 85% safety design. I’m not impressed.

]]> By: Cameron http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2636 Cameron Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2636 I'm in the outcast 15% -- not because I can't drive them safely, but because many of the rules are ridiculously conservative. They weren't designed for people who enjoy driving. I’m in the outcast 15% — not because I can’t drive them safely, but because many of the rules are ridiculously conservative. They weren’t designed for people who enjoy driving.

]]> By: Levi http://dan.hersam.com/2003/10/28/red-light-green-light/#comment-2637 Levi Tue, 30 Nov 1999 00:00:00 +0000 /?p=743#comment-2637 I'm curious about the 85% thing. What sort of vehicles fall in the 15%? If you remove traffic from the picture, small vehicles have a definite advantage over large ones when it comes to acceleration, braking, and corner grip, simply due to their lower mass. It seems to me that designing for larger vehicles then makes the road over-designed for small ones. Perhaps the 15% that aren't safe are really huge trucks? I’m curious about the 85% thing. What sort of vehicles fall in the 15%? If you remove traffic from the picture, small vehicles have a definite advantage over large ones when it comes to acceleration, braking, and corner grip, simply due to their lower mass. It seems to me that designing for larger vehicles then makes the road over-designed for small ones. Perhaps the 15% that aren’t safe are really huge trucks?

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