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

[DifferentPointofView]

I know that, I can see red and green, but these new lights are weird, unlike the old ones where you could see the light from all angles, the light can only be seen when looking at it directly. So these are called "lensed" lights now? They are nice when it's dark, not so much during the day. So the red one is normal and the rest are lensed? I'll take note of that. But I'll be blaming you all when I get pulled over or smash into another vehicle when I blow a red light because it's the new type :P Just kidding btw.

[SVOboy]

They have some of them around me, mostly on roads where you can see the other light changing and it tempts you to jump the green,

[hummingbird]

Spare me the rants, because what I am going to say will seem theoretical. I adhere to it religiously.

One principle in hypermiling is 'plan ahead'. Which means peak traffic conditions, number, nature and locations of traffic lights and sufficient time margin for any sort of crap happening enroute.

On a light that is not in your regular territory, I would play safe, and coast on. If I pass the stop line before the light turns amber, I am allowed to accelerate and clear the intersection before the other morons gun their vehicles. If you are not that fortunate, just kill the residual momentum (would not be much anyways), to minimize losses.

If this is a familiar signal, I would have my strategy of getting through it without coming to a standstill. That involves noting the distance to the signal, noting it's status, noting which side is passing a green, and that gives you an idea of when the signal is going to turn. All this calculation does not get into the system all of a sudden, you have to practice it, and it is tough sh*t to conquer. And that is where the challenge lies.

Jumping the signal or gunning for the green are mindlessly are far inferior options. Choosing between them is sorta asking "would you like a lump of clay or a bit of gravel will suit you better?" No offense intended, it is just my attempt to clarify!

[Piwoslaw]

Traffic laws allow running a yellow if stopping would require slamming the brakes and cause a traffic hazard. In a fuel economy oriented world I could imagine traffic laws permitting running a yellow or even a fresh red if the color change caught you towards the end of your pulse. On the occasions when I ran a yellow because it was almost impossible to stop on short notice at the end of my pulse, at least 2-3 other cars behind me would also keep going, I'm sure they caught the red. I keep an eye on them in the mirror, expecting red/blue flashing lights...

[NeilBlanchard]

The "freshness" of the red is in the mind of the beholder! This is a line that cannot be crossed, I think...

[SentraSE-R]

Add me to the list of those who continue gliding. I've wasted enough late pulses to have figured out it's not worth the gamble, especially when there's already cross traffic waiting.

[cfg83]

Hello -

I will admit to the occasional "im-pulse" on occasion. However, I think that "just saying no" to the pulse evens out over time. It's cool when I let fate decide and it goes yellow as I cross the intersection (I win!).

CarloSW2

[Piwoslaw]

Originally Posted by NeilBlanchard

The "freshness" of the red is in the mind of the beholder! This is a line that cannot be crossed, I think...

I couldn't agree more. I was by no means advocating that reds should be run, only imagining a reality more hypermiler-friendly: Longer red overlap with cross-traffic, or maybe longer yellows, and of course an LED display showing seconds until color change.

[hummingbird]

Displays showing seconds to next green are a commonplace in India. Also sometimes the red lights have "RELAX" or "CHILLAX" written on them. People are encouraged to shut off engine when waiting for a green.

There is something called PCRA - Petroleum Conservation Research Association, that funds such advertising, and promises a blanket 20% increase in FE to everyone on taking a few simple actions. Good for us!

[Old Mechanic]

Originally Posted by MetroMPG

There's the key point.

If you throw in another pulse, and the light does in fact change to red, you're forced to brake (or run it, if you're igo ) - and probably brake pretty hard. Gas in --> brake dust out = FE nightmare.

If you keep gliding and the light does in fact change to red, you're far better off than if you had pulsed & braked (since in this scenario, I mentioned you would pretty much coast to a stop at the intersection anyway).

I really did face this situation a few drives back. As it turned out, the light *didn't* change to red on the approach, so I ended up re-applying power just as I got to the intersection (having almost coasted down to zero).

It's a completely bizarre, non-intuitive tactic to use. Green means go, right? Yet there I was, coasting nearly to a stop facing of a green light (NOTE! Not affecting any other drivers.) But if max mpg is the goal, only a predictable green means go.

Waste no inertia is my basic rule. The Insight fuel economy display clearly shows a significant loss in average mileage from a single forced stop from any decent speed, with the resulting acceleration from the forced stop.

Gliding is your best friend when it comes to extracting the best possible mileage. The key to your scenario is knowing you can coast to a virtual stop regardless of the light condition.

I would only pulse when I knew I could make it through the intersection safely and without any legal risk.

I always give myself plenty of time to reach my destination, so there is no impulse to push for time saving.

regards
Mech