Driving the Speed Limit

[Kyle]

Typically I set my cruise control for three miles an hour over the speed limit, and that's how I drive 95% of my commute (the rest of it is below the speed limit due to traffic).

But recently I've decided to drive the speed limit. Let me tell you-- it's the best. Y'all. Seriously. Benefits: (1) you are weaving in and out of traffic less, which I'm guessing is safer, but is also much more zen; (2) you don't think twice when you pass a cop- so slight pump on the brakes to come down to speed- just cruise on by; (3) better mileage.

There are no drawbacks other than the extra 60-120 seconds it takes me to get to work. Y'all! This is the best!

[Tahlvin]

Around here, I usually go about 5-10 MPH over the speed limit; more during rush hour, when traffic is generally going faster and 10 MPH is what's needed to keep up with the flow, and more towards the +5 MPH side of things when traffic is lighter. Experience has shown that police in this area will not pull you over unless you're doing at least +10 MPH over the limit, so so I usually will do +5 to +9 MPH over without even bothering to slow down if I pass a cop car.

For longer drives, I usually do about +5 MPH over, but many times will back that down to speed limit in order to avoid the stress of getting mad at slower drivers who insist on using the left lane, as well as improving gas mileage.

[Kyle]

So I do a lot of driving and I drive through a lot of towns with heavy traffic and the idea that "our traffic drives fast, and if you don't go that fast, it's unsafe." And here's my conclusion on that- that statement only applies to the fast lanes of travel- and those lanes are easily the least safe on the highway. No matter where I am- Atlanta, Dallas, Houston, Austin- whatever- there's always at least half the lanes where it is safe to drive the speed limit. And it's safer.

And I get the idea that cops won't pull you over for going 5-7 over the speed limit. But some will. And then you are watching for cops. And that's my point! Do you know how pleasant my drive is when you don't have to watch for cops? It's the best, y'all!

[poorpete]

I speed on a curve.
Speed Limit => How Fast I Go
20 => 20
30 => 30
35 => 38
45 => 50
55 => 62
65 => 74

[Kyle]

For both Tahlvin and poorpete- you should try driving the speed limit for a week. Even in those excruciating sections where you know you can speed. Don't. For just a week. As an experiment.

[Tahlvin]

[Eliahad]

In town, I drive pretty close to the speed limit. Once I'm on the highway at 75+? I'll go 80. Keep in mind that I'm sometimes covering 100+ miles (one way) to get to my jobs.

[Phoebe]

Hee hee Atlanta. LOL. Dying. Atlanta!



Driving can be a form of art. Usually it's all happy little trees, very relaxing.

[FlameBlade]

Adaptive Cruise Control is awesome. I got through a stop and go traffic without touching brakes or gas. So nice to have that freed up so I can focus more on stuff around me.

That said, because of drivers locally, usually 7 above the limit. ACC makes me not worry about braking or speeding up if I am behind a car that is at speed limit.

[Stan]

I get the idea but my experience in more in line with Tahlvin's. I rarely pass. By going 5-10 miles above the speed limit, I'm going the same speed as most other drivers so have the least interaction with other drivers. This is especially true on 465, the beltway around the city. If I go 55, I'm constantly at risk of getting rear ended, even in the slow lane.

Part of this is determined by the speed limit. I've noticed going across states that speed isn't perfectly in line with limits. At higher limits, people are 0-5 above the limit. At lower limits, people are 5-15 above the limit.

[Kyle]

[bralbovsky]

I've been trying lately to do this.

On the bike, if I did, I would not be here. Flow of traffic: being passed by 50% of cars and passing 50%, is 10% or more over posted. One reason I chose to stay off interstates if practical.

So I confess I used to violate rules of time and space routinely. I'm trying to train myself for when I'm not even driving anymore.

[Bluedevyl]

My speed tendencies fluctuate depending on who else is in the car. If its just me, I'll generally be 5-10 miles over the speed limit. If the kids are in the car, I don't. Maybe 2 or 3 miles over the speed limit if I'm passing someone. Otherwise, I set it at 65 and leave it there.

[Mike]

Two identical cars are side-by-side on the interstate. One is travelling 70 mph. The other is going 80 mph. There is an overturned truck completely blocking the road ahead. At the exact moment that the two vehicles are exactly even with each other, they both start braking as hard as they can. The vehicle that was going 70 manages to stop precisely before the moment of impact.

How fast is the other vehicle traveling at the moment of impact?

[Walrus]

[Mike]

Actual answer... while the first car brakes from 70 to 0, the second car goes from 80 to 39 over the same distance. 10 mph over the limit (in this case) means you're still doing 40 by the time a law abiding car comes to a complete stop.

[Bonefish]

Really Mike? You need to show your work.

[Walrus]

I call I think I was just as technically correct lol

but yes, the reduction in speed becomes something like a logarithmic graph when compared to initial speed I think - or maybe it is parabolic or something, either way, the largest percentage of deceleration happens in the very last few metres.

I still stand by my answer though.

[Phoebe]

The main thing is that one shouldn't speed beyond a number of factors that influence how well you can control your vehicle and avoid potential collision, including stopping distance. The road is supposed to be built to offer a certain safe sight distance for stopping, which includes a few seconds for reaction time. (Fun fact: this used to be my job.) In heavy interstate traffic, cars are almost never respecting safe distances from the car ahead for the speeds being traveled, unless of course everyone is crawling along. But when you're all doing 65 or 75, even if it's the legal speed limit, and everyone is following too closely, everyone is collectively screwed if a sudden false move or obstacle appears. But people going too slowly create their own kind of road hazard. If going 70 instead of 80 gives you a shorter stopping distance, well, going 60 makes it even shorter. But going 60 when the speed limit is 75 could help cause the problem that makes everyone need to stop suddenly, so...

The point is, excessive speeding is relative to the circumstance, and when you're in traffic we need to give a much longer berth to the cars in front than we may think, and as we age.... etc etc my reaction time is probably a full second slower - this includes both cognition and then taking action with your body to engage the vehicle.

[Walrus]

As Phoebe said - it's complicated.

My personal bugbear that makes me hate humans and want to go on killing sprees when driving highways especially, is when I leave an appropriate distance, and every jackass and his freaking dog seems to think that is a good place to insert themselves, necessitating I break to get back to a safe distance, only to have some other jerk jump in. The day I get a mounted rocket launcher, the road gets to be a much different place!