Hypermiling and Safe Driving Distances

My "rule of thumb" is 1 car length for every 10 MPH. Of course in practice, someone will invariably pull in front of me.

I'm happy to see a car length per ten mph is still alive. They have that 2 second rule wanting to be really thee one and; some of them trying to say one car length per ten mph never existed. Since I was seventeen over thirty years ago that is thee only distance rule and to me it saves more lives. It's going to be a mandatory distance like seatbelts and headlights in the rain, and will work, make a difference, and watch what else. No offense to one two but; here lets try ready: one...two... telephone booths?, I mean poles, trees, cactuses, sorry, hun what are we passing right now? one two uh, missed that one try again; one two uh, again; one two pwuuuuuuuushbkkkkkkkkkkkoops.

Distance, going to save lives. 38,000+- lives lost! Well to many each year and is going to start decreasing dramatically.

This is a reply to myself. I'm knocking here in the USA on the second rule particularly because of a NJ DOT who claimed the one car length per ten mph didn't exist and we had to pass it on our written test. Distance is thee number one to saving lives, eliminating accidents, traffic jams, and road rage so; however we maintain it, as long as we are maintaining it. One two is good for me when its good for you.

UK Highway Code recommends at least 2 seconds.

The full Highway Code is here. The safe distance/time is discussed in section 125.

Some more discussion here, including a note about chevron road markings used on some motorways. The chevron marks are about 125ft apart, giving 2.4 seconds between cars 2 chevrons apart @ 70mph (the national speed limit for cars).

'Only a fool breaks the two second rule' was a safety slogan a while back..it makes a lit of sense...however like Brickie says...some pillock generally fills in your gap.

There are plenty of nutters who sit a cars length behind someone at 90mph presumably thinking their ABS will save 'em.

I pride myself on knowing what's behind me and if one of those guys comes up on me in a stream of traffic I raise my hand to achnowledge I've seen 'em (and hopefully keep 'em off by arse). I'll then get over as soon as there's a safe gap...If they want to bulldose their way through the traffic and clear a path maybe I'll follow.

I try not to get too annoyed with them...you never know they might be rushing to get to someone in intensive care... I know I was once .... (or it maybe it'll be themin intensive care soon ).

Anyhow with the price of fuel now I keep closer to the speed limits (eg +10mph max)

Del

I know how you feel about the the guys on your bumper. I usually follow twice the distance recommended. Half for me and half for the guy on my bumper.

If you're on a multiple lane road stay in the lane that allows the faster cars to automatically pass. Here in the US its to the right, and we're still not coordinated yet, yet will be soon. Pass on to your engineers to multiply speed on multiple lane roads, low to high. It automatically makes things better; and I hope the usual doesn't happen and things are said like we're coordinated with thee electronics and lights, it won't work, things like wet roads and, I forget what else was said, something really second grade ish.

Distance with speed; however use it at all times.

Don't forget 'Think once, think twice, think BIKE!', 'Clunk, click, every trip!' Anyway, back to the topic at hand! I'm a three second man and change down a gear when coming off the motorway man! Always works for me especially in Spain where some of the slip roads are so short they are dangerous! Here in Spain, the tailgateing problem is crazy! Bumper to bumper (less that half a meter) at 120kmh and faster! We have some really nasty accidents but still they do it! It make me wonder about the mentality of these people!

Good answers everyone.

Another aspect of this question is...How far past a vehicle should you be when you pull in?

I've been guilty of tailgating too close during rush hour traffic and very infrequently I pull in to close to a car, either in front or back.

Yeh, I must admit I get a bit impatient and close in slow urban rush hour traffic..., but on the motorway I leave plenty of room. After all a bump at 20mph isn't going to kill you ...but at 90mph.

The people who wind me up are the ones who sit for ages in a traffic jam...then finally when the yget to the front and the lights turn green they p-u-l-l a-w-a-y r-e-e-e-e-a-l s-l-o-w do they enjoy sitting in a jam.
Del

Seems to be a bit of a regional thing. Sit at a green (or even red-and-amber) light in London for more than 2 sec, and horns will be blaring. In remote parts (I'm thinking bits of Scotland), you'll be lucky to get two cars through between changes of lights.

Reading is a bit of a mixture. There are some who burn rubber at the first flicker of a light change, and some who are still trying to find the biting point as it goes back to amber. I guess it's 'cos Reading is now such a mixture of this'n'that.

The distances between cars seem to be roughly proportional to the getaway times from the lights.

(Note: this is all referring to town driving).

You all know everything is always good, and all these ???s and answers are great. If you don't mind me saying real quick, my last response wasn't to Maryland, it was to thee above, but related to both. Now on getting back in after passing; depending on what's happeing, if things were perfect, moving over two or more + car lengths after you pass is good; you're going to be increasing distance automatically because you're going faster; and if that driver reduces speed in the least just for a little allowment, the diistance will increase so much so fast everything will be kinda honky dory immediately. These things are going to be. Apply more distance at all times and allow when you can, and hopefully be offered the same in whatever situation.

Safe driving to all at all times.

I try my best to maintain a three-second gap, or at least three vehicle lengths between me and whatever's ahead, and as someone mentioned, I look past them at what the lead vehicle is doing waaayy up there. More often than not, I touch my brakes before the third car up ahead does because I've been reading the road. As for pulling back in front of who I just overtook, I check my side mirror. If I can't see BOTH his headlights, I stay put. That usually triangulates to at least a couple of vehicle lengths. Never been in a fatal crash yet!

Brakes? You need to use the brakes?
I look soooo far ahead I can just ease off the accelerator...why I coasted all the way into work this morning. .

Del

It's 3 or more seconds for me. Unfortunately, it can drop to 2 or less when some fool pushes his way in between me and the car in front.

Yes, there is a law against tailgating. I can't remember exactly what it says because it says "so-many-meters-for-every-kilometer-per-hour" which is difficult to calculate (especially with an under-developed Vulcan brain ).

I usually drive at 60 kph on average. I get an occassional tailgater but these usually overtake as soon as it's clear. If it's just him and me on the highway, I slow down until he gets irritated enough to drive past.

I have yet to hear of a case of road rage here where drivers chase each other. The only forms of road rage I hear about are those where drivers get out of their cars and deal with their differences mano-a-mano.

On one when that fool is right in front again, just let up and that distance opens right up again. It works.

To me tailgating is on them. If they're that close and you have to for whatever reason slam on your brakes and they hit you, it won't be to hard hopefullyright, and you get to sue their basketballs off; hopefully never. Things are changing.

Difficult to sue when you are dead...and whiplash would make my golf swing even worse...

Dunno why we havn't got automatic distance control controlled by doppler radar...could have had it years ogo except for macho idiots who want to kill us all. (I notice this stuff is slowly creeping in now as 'collision avoidance')

Del

I think it is starting to become available. Adaptive cruise control.

I rarely check the distance or time, I usually space myself by how far I can see. If I'm in a van or pickup I can usually see three or four cars ahead. Based on conditions I will hedge on being closer or further based on what I see 1/4 to 1/2 mile ahead.

I am also becoming like Del in trying not to use the brake (brakes? what brakes? We don't need no stinking brakes!) So if I have a highway exit or stop light far ahead, I try to get off the gas early and coast as far as possible.

Of course when I'm in a short compact, forward visibility is impaired so I will leave more space.

I have started to stretch that 2 second space a little more as I become more tolerant of those idiots. That has forced me to drive in the left lane less.

As for tailgaters, as parts keep falling off my truck, most tailgaters decide to back of some.

Our Northern Territory Government only imposed a 130 km/h speed limit on us about a year ago. Prior to that it was open slather on the open road. Apparently if charged by the police, offenders merely had to prove they were driving in a safe manner and to the conditions.

I usually make the pilgrimmage from Adelaide to Darwin once a year, mostly in a 4WD. I am normally the slowest vehicle on the road, sitting between 110 and 120 km/h. Because the highway is so long and straight, road trains and cars zip by as though I'm standing still. If I encounter a grey nomad or other slow mover, I sit a good 3 seconds behind until I get room to pass.

I honestly don't know what the NT Government's legislation has to say on the subject of tail gating.

I've always used "one Mississippi, two Mississippi", etc. as my rule of thumb for driving distance. At higher speeds, I do leave extra room, always watch out for the fools around me, and use a racing technique, "drive beyond" the car immediately in front of me...observing several cars ahead and behind.

Many people key off of the car immediately ahead, and that's a major cause of collisions, in my humble opinion; the fourth or fifth car ahead starts braking or moving about suddenly, the followers key off of the car immediately ahead, and the pileups start when people can't stop in time.

I like Mississippi better then poles and trees, you're past them to soon. We're going to do our best make all kinds of distance practices mandatory to keep things like pile ups from ever happening. Keep it standard, drive on.

In icy road conditions on regular tyres? "Halve your speed and double your distance" works quite well as a rule-of-thumb.

Good stuff, no bout adout.

Ride on

I used to manage a branch office for a transportation company. All employees were required to take a defensive driving course from the national safety council. Their course recommended a three second following distance in a passenger car in ideal conditions (daylight, dry pavement, etc.). They additionally recommend that an additional second be added for larger vehicles and for each individual hazard faced (ie. for an suv(+1) traveling at night(+1) in rain(+1) following distance should be 6 seconds). As for laws aginst tailgating, I believe every state in the US has laws on the books prohibiting following too close. However, I've never heard of someone being cited unless they've been involved in an accident.

Hi ddk,

You're right to say that if vehicles on the road followed closer together then there would be a direct savings in fuel. This fact is demonstrated everyday in auto racing. Also, since most vehicles stopping distances are about the same there is no real reason why vehicles should not be able to follow close behind each other. The problem is the drivers.

A skilled driver who is fully alert and focused on the task of driving is quite capable of following only a quarter second or so behind a lead vehicle while reacting to changes in speed of that vehicle. However, this is much harder to do while staring blankly at the dotted line in the middle of the road or sending a text message with a cell phone.

Perhaps one day cars will be equiped with sensors that will cause them to automatically slow down without first having to wakeup the driver. Then the world-wide economy and global environment will benifit from the savings generated by lower wind resistance thanks to good engineering.

To answer your questions:

1. In Western Kentucky the rule of thumb taught in driving school today is to follow "2-seconds" behind the vehicle ahead of you.

2. There is not a specific law that says, "tail-gating is illegal," but "following too close" is cause for the police to pull a driver over and ticket him or her for aggressive or reckless driving.

Welcome aboard! I doubt a quarter second would keep you safe. The reaction time to a surprise move ahead of you can be longer than that.

I myself do not follow close to other vehicles unless traffic is so thick that I have no choice, and if someone tail gates me I pull my vehicle to the side of the road and wait from them to pass.

People do follow a quarter second behind all the time - especially in thick traffic. The result of this is that tens of thousands of accidents occur every day and hundreds of thousands of close calls, but millions more vehicles get to work every day and have completely uneventful commutes 4.99 out of every 5 years, so generally speaking a driver is capable of following very close to another vehicle.

My point is that even though it is possible human drivers should not follow each other closely because we simply are not very good at staying focused. While following closely does save gas on the way to work it eventually catches up with the driver and costs him or her thousands of dollars in repairs and even worse if injury results.

I would never trust people to drive that close all of the time, but I see skilled drivers do it very easily during auto races, but their minds are on high alert and their reactions are working at peak. However, I would trust proven technology which is probably only a few decades away.

The 2 - 3 seconds rule is difficult to follow. The easier way for safe conditions is to apply the speed in yards as the following distance. I use this rule in good conditions and it is similar to the 2"rule. For 80 mph, the following distance would be 80 yards.

Calculating 80 mph yn yards are 140,800 yph. Divided by 3600 seconds per hour are yards per seconds =~40, x 2 seconds rule = 80 yards in 2 seconds. Very simple way to calculate distance by speed.

Nothing like a good wise guy

I'm sorry but that is just (in my opinion) complete rubbish not right.
Most people can neither do the mental arithmetic not accurately judge distance. But most can count 'one thosand and one, one thousand and two'.

As a golfer, I know hit my pitching wedge 75yards...but I need to pace it from the 150 yard marker. On a featureless road it's virtually impossible to accurately judge distances straight ahead.

Del

The question was:

1. What "rule of thumb" do you use for safe following distance?

The answer was for MY rule for distance.

You pointed out an ability to judge distances that I was unaware others don't have. Sorry for your inability. For those who can judge distance, here is a different rule.

Other people cannot concentrate on traffic and at driving, and at the same time on a fix object and counting 'one thousand and one...' like me.

If the distance judgment thing does work for you (not that I'm doubting your word), I think you're a lucky guy. I don't think there are too many people around who could do it reliably.

For me (unless the road is marked with chevrons or whatever (see #2)), I'll stick to counting elephants. Don't know what it's like where you are, but here it's pretty easy to pick up on a roadside marker to start & end the count.

Don't need to do it all the time - once I've got an idea of the distance (derived from the time, at a particular speed), I can fix on that for a while, just occasionally checking (using the counting rule) when the general traffic flow slows down or speeds up.

I found the road asphalt was very hard on the yardsticks.

I was hoping to get a few more replies from other countries. India, China, Austrailia to name a few. Just to see what their rules of the road are.

Under Secretary of Transportation Dole, the US starting requiring a third, high mounted brake light. I've always thought that a yellow light going on when the driver lifted his/her foot off the gas would have more of a safety benefit due to the earlier warning that the car ahead might be about to stop.

I remember in the 50's, a miniture street light was available that lit green when accelerating, yellow when slowing, and red when braking. As is typical of our government, the DOT only tested one idea and didn't look to see if there might be a better one.

I always thought a little blue 'sorry light' could defuse a lot of road rage...we all screw up ocaisionally .

Del _{<Bump crash thud...little blue light flashes on...>}

We have those little blue flashing lights - but they are only on certain cars...

Some of the transit busses in south Florida have gone back to these amber lights.

Two seconds on clear day with dry roads

Three seconds in bad weather.

Yes we have laws. Unfortunately, they are usually only enforced if they cause an accident.

To your second question (re. the law) - the UK road laws don't seem to have any definite rules - it's all a bit fuzzy, as far as I can make out.

The Highway Code is largely an advisory doc - though it also spells out the mandatory stuff. Note that there is no legislation cited (no 'MUST/MUST NOT') in the relevant sections - 125 & 126.

I think it boils down to three possible outcomes if someone is found guilty of causing an accident or exacerbating the results - Careless Driving, Dangerous Driving, or Causing Death by Dangerous Driving. Any of these could involve tailgating, but getting the evidence is the tricky bit.

The law generally does stack up against the guy behind - i.e. the tailgater.

[Sorry if I'm waffling ]

Of course the time it's easy to get caught out is when you are driving at a sensible stopping distance in a slow moving stream and you don't realise the speed has slowly crept up from 40 to 90.... oh I mean 70 officer.

Del

Good point there, tho'. With the 'distance' method you have to continuously monitor your speed - which means eyes off the road. The counting method means you don't need to.

(I accept it's a good idea to check the speedo from time to time to make sure you're both within the law and at a safe speed for the road conditions (tho' for me, the latter tends to be more 'felt' than by checking the actual mph)).

Heh, I have no need for safe driving distances or laws about tail gating. I'm married. My wife will tell me EXACTLY what I'm doing wrong