Technique quandary: gliding toward a stale green light - to pulse or not to pulse?

[MadisonMPG]

This depends on a lot of things. Here's a mini check list I go through:

How long is this yellow? (if it's a light I go through regularly)
Sensor triggered or timed?
How large of a road? (smaller triggered roads tend to trigger faster for stopped traffic than larger roads)
How fast am I going?
How close is the car behind, and what has his behavior been like thus far?
Cops?

95% of the lights in my city are "trigger" lights, so I coast down if there is cross traffic that has been there. Most of the time I have a commit distance made up in my head well before light switches yellow, if I am passed that number I accelerate or continue coasting. If I am behind I usually coast to a stop/brake.

[dcb]

yah, those are all good inputs, I might also weigh in if it looks like a high pedestrian area or not, don't want to be terrorizing the peds w/my speeding metal box.

But usually I keep coasting, nothing more frustrating than slamming on the brakes after a long burn.

[PaleMelanesian]

Coast. Nearly every time I break that rule I end up slamming into the red. Each time I swear I'll never do that again.

I have one of these on my route home, in the middle of the worst uphill. I hate it. I usually hold steady speed ~30 mph in 5th gear until the "commit" point - either eoc and stop or give more gas and go. At 30 mph uphill, the commit point is very close to the light.

[orange4boy]

Coast. Nearly every time I break that rule I end up slamming into the red. Each time I swear I'll never do that again.

Ditto!

I almost never pulse up to a green anymore. I've had too many "D-oh!s". Just one of those gambles lost murders your FE.

[Bearleener]

1) Our indecision is telling us that our fuzzy logic processors (our brains) say it's a close call or there's too much uncertainty to tell.
So if we trust our gut instinct and experience and decide instinctively on a case-by-case basis, then on average we've probably optimized it.

But it just hurts so much to slam on the brakes right after a burn that I usually just coast and enjoy the scenery; I've placed my bet, now fate decides.

2) To those fellow red/green color blind: LED's are very monochromatic compared to incandescent stoplights. So if that single wavelength happens to be in the part of color space that you can't distinguish well, then you're outta luck. With multichromatic light maybe there are other wavelengths that still allow you to differentiate red and green lights. But I usually have more problems at night distinguishing between red and yellow, and not between red and green (which is much more whitish to me).

3) Getting information on when stoplights will switch: I spoke to the traffic control center in my city, but they said that because so many lights are traffic- and pedestrian-controlled there's no way to provide, say, a car's navigation system with reliable data to inform the driver. In Ingolstadt, Germany there was a pilot project called Travolution
Audi Travolution Project Minimizes Red Lights and Emissions
in which, among other things, each stoplight informed approaching drivers over their infotainment system about what speed they need to maintain in order to roll through the green light. Presumably you could do this on a large scale if every stoplight had a small FM transmitter, which the car radio receives and passes the data on to the navigation system. Or better yet, the cars ahead of you tell you if they're standing at a light or in traffic, or moving (or for that matter, if the road is slippery i.e. they're using ABS or ESP alot).

[RobertSmalls]

Sometimes you coast up to a green and it's the wrong decision. I did that this morning. I coasted towards a stale green, down to 40mph, and got close enough that I'd have to use my friction brakes if the light turned. Then I decided it wasn't going to turn, and I departed from optimal BSFC to get back up to 60mph quickly.

[user removed]

Coast.

This one of the reasons I drive the Insight in local trips and the VX on highway trips.

The first 7 miles of my daily drive only involve 1 traffic light. I know when I see the light as I come around the approaching curve, if its green, there is no chance of making it through the light, so I slow down and generate some battery juice.

If the left portion of the intersecting road is moving I know the light will be green when I get to the intersection so I maintain my speed. Sometimes I will pulse to a higher speed when the same traffic has been moving for a few seconds.

If the right intersecting traffic is moving I will coast without regeneration, which puts me in a perfect position to reach the light at the highest possible speed, even when there is stationary traffic in my lane headed in the same direction.

The next light is 3 miles further down the road on a slight uphill climb. I can see the light about .4 to .5 tenths of a mile away. The last sequence of traffic flow is the oncoming left turn signal. Ideally I want to be about .2 mile from the light when the left turn oncoming traffic flow stops and my light turns green.

After this first 7 miles, there are 12 lights in the next 3 miles, some of which are newly installed and very poorly timed. It used to be that you could average 47 MPH and hit every light green. The speed limit is 45, but if you go that speed you would catch a yellow light at exactly the wrong time and have to stop quickly.

Sadly the newly installed lights are not timed properly and you are forced to make a decision as to how you react. It's almost impossible to maintain any decent average speed without getting nailed by one of the newly installed lights. Its sad because the traffic at these lights is almost non existent and it is especially stupid to have them individually sequenced which causes 25 cars to slam on their brakes for a single car to enter from the intersection.

In this case I revert to the coasting scenario, and all the cars around me get aggravated by my extended coast to the light, only to have me glide past them as they stomp on the gas when the light turns green again, on this 6 lane stretch of road.

regards
Mech

[IsaacCarlson]

Originally Posted by PaleMelanesian

Coast. Nearly every time I break that rule I end up slamming into the red. Each time I swear I'll never do that again.

Yeah, I am still learning to glide/coast to a stale light. Almost every time I decide to test it and hit the gas it changes and I have to hit the brakes.