Wanted: Documentation of Dangerous Drafters...

Discussion in 'General' started by Chuck, Aug 6, 2008.

?

How many Instances of Close Drafting Semis to save Fuel Have You Seen the Last Year?

  1. Several times a day

    0 vote(s)
    0.0%
  2. Daily

    4 vote(s)
    4.2%
  3. Weekly

    6 vote(s)
    6.3%
  4. Monthly

    6 vote(s)
    6.3%
  5. Once in the last 3 months

    8 vote(s)
    8.3%
  6. Once in the last 6 months

    4 vote(s)
    4.2%
  7. Maybe once in the last year

    15 vote(s)
    15.6%
  8. None

    46 vote(s)
    47.9%
  9. I close draft

    7 vote(s)
    7.3%
  1. R.I.D.E.

    R.I.D.E. Well-Known Member

    The stripes are about 43 feet apart from beginning of the stripe to beginning of the next stripe. Right at 13 stripes per tenth mile. Looks like about 100 yards to the truck in front of you, maybe a little more.

    regards
    gary
     
  2. jhu

    jhu Well-Known Member

    What's considered "drafting"? I'm usually 2-3 seconds behind the slowest vehicle I can find, and that's usually, but not always, a semi. That way people behind me can see that it's the guy in front of me that's slowing everyone down...
     
  3. St. Mushroom

    St. Mushroom doesn't wash his car.

    My understanding is that to actually draft a semi, you have to be all but kissing its bumper. Which is incredibly dangerous, and it's not like most of semis are traveling at optimal efficiency speeds in the first place, but rather too fast on the highway or too slow on local.

    I remember they used to teach us to follow at four seconds. Increasing to five or six can only reduce brake usage, right? Aside from the hotdogs darting into the gap right in front of a stop light...
     
  4. Chuck

    Chuck just the messenger

    The wake may be about as long as the trailer.

    I usually go at a speed the semi is not around me for long, and I clearly was not tailgating.

    This thread stems from the hundreds of hypermiling stories in 2008 that declared all of us are drafting semis and rolling thru stopsigns. In a few instances, it was apparent the writer of the story knew this was a lie, but wanted to promote the myth anyway. :mad: Others lazily just repeated older articles with little research.
     
  5. some_other_dave

    some_other_dave Well-Known Member

    There is actually some benefit to be found in following a semi at ~2 seconds of distance. It is an awful lot less than that from getting right up on the rear bumper of the semi, but it's a whole lot less likely to get you killed.

    And, as noted, if you can get behind one that is going somewhere near your preferred speed, people won't get as agitated being behind you; they can see that the semi is "holding you up". I was able to drive ~15 miles at 45 MPH on the freeway that way a week or two ago. :D

    Though most of the time the trucks around here are running at 60+, which is faster than I want to go.

    -soD
     
  6. JusBringIt

    JusBringIt Be Inspired

    I just thought i'd mention having a really good laugh at this knowing how true it is. :p
     
  7. some_other_dave

    some_other_dave Well-Known Member

    Some jerk in a Volvo wagon was exhibiting the worst of what I think of as "the Volvo Syndrome". They were following less than half a car length on a busy four-lane road that has stoplights and a 35 MPH speed limit. They stayed that distance behind the car in front of them as the one lane they were in got onto the freeway, and as everyone accelerated to 50+ MPH. Half a car length, right around six feet, between the bumpers of the two cars.

    It's "Volvo Syndrome" because it seems like some Volvo drivers feel invulnerable, because they drive a "safe car"...

    And if you were guessing that I was the car being tailgated for part of that time, you'd be right. But when I moved over (Reverse Pass FTW!) they just got right up on the car that had been in front of me... Sigh!

    -soD
     
  8. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    It's like they view changing lanes as a difficult task. It's not exactly rocket science, now is it? :confused:
     
  9. Ptero

    Ptero Hydrogen Nut, Battery Skeptic

    Well, I just finished reading this entire thread and it's pretty sad. It's pretty sad to see people who claim to be hypermilers criticizing real hypermilers for actually hypermiling.

    You know, Wayne didn't invent hypermiling and a lot of you folks who think you know everything were in diapers when I started hypermiling and drafting in the 1960s. I draft big trucks every chance I get. I enjoy it. I like sneaking up behind them and tucking into the vacuum zone so close that they can't tell with their mirrors that I'm back there. I just let 'em suck me down the road on their dime.

    A good technique is to get up close behind some yahoo who's thinking he's smart and stays in the right lane except to whip around trucks, thinking like the idiot he is that the cops won't see him weaving around traffic. When he whips around the truck I choose to draft, I drop off Bear Bait's bumper and settle into that sweet 1-second range and slowly whittle it down until the buffetting drops off, right foot on the gas, left foot lightly touching the brake.

    I'll draft a truck crosscountry. I'll fuel with him. We'll go 500 miles together. I'll pull off at a truck stop and fuel my itty bitty plastic car and check out the trucks at the fuelling bays. I'll look for a company truck using satellite tracking. Some of these are limited to 60 or even 55 mph. Then I look for flaps - flaps running all the way across the back of a box trailer if I'm lucky. And just as important, I want a truck that's empty or light. They can't stop as well as a loaded truck. A driver won't slam on his brakes with a light trailer. It flat-spots the tires and he catches hell back at the yard. You can judge his load as he pulls away from the truck stop. An empty trailer bounces, a loaded one wallows. If I'm running with a CB, sometimes we'll chat. They never care if I draft them when they know I'm a truck driver. They know I can't hurt them, anyway. Most times we just reach a silent agreement. Once in a while, some dick will get a hair up his ass and tap his brakes so I'll just back off and pick another truck.

    I got a triple-A card. I got a million-mile-safe belt buckle. I'd have one for the second million if I'd cared to ask for it. Some people shouldn't draft. I'm not one of them.
     
  10. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Ptero, it's your life but I'd sure hate to see you lose it because you'd rather live dangerously at a higher speed. :(
     
  11. lightfoot

    lightfoot Reformed speeder

    ptero, most of this has been said before, but drafting is not a recommended hypermiling method because:
    (1) it's dangerous
    (2) it doesn't save as much gas as simply slowing down does.

    It's dangerous because you must be REALLY close to get most of the benefit, and then there is almost no reaction time. If the truck slows suddenly. If the truck straddles debris (gator strips of shed tire treads, broken pallets, any of the stuff that litters our highways). If the truck sheds a tread.

    Drafting forces the drafter to make constant speed changes to match the semi, even on a flat road. This burns more gas than driving to accommodate the terrain does. And P&G is impossible while drafting.

    The draft drops off rapidly with following distance, thanks to air plunging down off the back of the roof of the trailer (and swirling in from under the sides of the trailer for anything but a moving van). Yes there is some draft further back but the benefit drops off very quickly and becomes mainly turbulent air rather than a clean draft pocket.

    For the record, I was a bicycle racer in the '70's and on training rides I used to draft semis and anything else I could, including buses, motor homes, and even mopeds (cars don't work very well because they are too low and change speeds rapidly). Part of our training involved drafting a scooter (ridden by a teammate) for 32 miles, averaging 35-40 mph. On a bicycle you can feel the air currents against your skin. To draft a semi, you had to stay within one to two feet of the rear tires. If you dropped further back, you could feel turbulent air spilling down off the roof and could not catch back up into the air pocket. BTW, we stayed behind the left rear tires to avoid debris straddled by the truck and to be able to see a bit ahead around the side of the trailer, accepting the risk of a trailer tire blowing. Now all of this seems foolhardy, but learning about semi drafts was useful.

    Later on I rode motorcycles and avoided getting close behind trucks because the turbulent air slapped me around too much. Still later I tried drafting a semi with my Subaru, and the ScanGauge showed that I got better mpg doing 50-60mph P&G than I did drafting, on the same stretch of I-95.

    Why not get a Scangauge and do the same experiment for yourself?

    Maybe this thread could be retitled "dangerous tailgaters" because as has been pointed out most of the people following really close are simply tailgating and have little or no intention of drafting.
     
    Last edited: May 12, 2010
  12. Chuck

    Chuck just the messenger

    Ptero, three weeks ago the "Drill, Baby, Drill" folks also threw caution to the wind - look at offshore drilling now.

    Same goes not just for drilling, but other activities, including hypermiling.
     
  13. Xringer

    Xringer Older Member

    Hydrogen Nut? LOL!! Are you sure about the Hydrogen part?

    Why do I get the feeling your post is just a trollish joke??

    If your post is for real, I'll say a prayer for any passengers in your car, and for
    those other cars, that might get killed crashing into a fireball on the road..

    Anyone who knows how to rack up good MPG, understands how fast they can drive
    before they are way past the MPG sweet-spot.

    Around here (US-95), it's pretty dang rare to see trucks driving the speed limit or under.
    90% of them are speeders and there is no way most Hypermiler is going to try to keep
    up with them.

    Like what's the use in drafting, if you are only getting 20 MPG??
     
  14. Chuck

    Chuck just the messenger

    Now for my long answer.

    Of course what we call hypermiling has been around for a long, long time - probably since before WWII...the best promoters are not necessarily the inventors.

    I'm not spending time on the safety of tailgating semis - that's pretty obvious.

    Ptero, I'm glad you have a problem with us condemning drafting.

    You have been here long enough to read stories from the media and truckers that attempt to portray hypermiling as the #1 highway menace, recklessly drafting - why give these lies credibility?

    We live in a sad world that many think their agenda is better advanced emoting BS rather than a sound argument. A good example is those that claim Barrack Obama is a closet Muslim without authentic US citizenship. :rolleyes: There is way too much button-pushing and not enough honest discussion these days....hypermiling has suffered this too.

    Much of the hypermiling-bashing is from speeders that somehow feel threatened - they don't reason - they fight in the manner of political arguements just mentioned. A few are not on speaking terms with Wayne - or me. One guy was so hostile he can't even call me by my real name and is the only person in the room that thinks I'm say - like Charles Manson.

    Come to think of it, your post was pretty emotionally charged - Ptero.
     
    Last edited: May 12, 2010
  15. Ptero

    Ptero Hydrogen Nut, Battery Skeptic

    I figured this was a great way to make myself popular around here. Still, some of you people are severely misinformed. Close drafting is not tailgating. Tailgaters have their foot on the gas. Close drafters have one foot touching the brake and are primed to use it in a millisecond.

    [​IMG]

    1) Close drafting actually does works really well. Better than almost everyone thinks.
    http://www.teammccallusa.com/history.html

    2)
    No one will ride with me when I close draft. They find it too stressful. But that is subjective. The important factor, as I've mentioned before, is the closing speed. When you are close drafting a lightly-loaded big rig at highway speed, you are not going to be able to generate much closing speed if he slams on his brakes - even if you do not react. You will hit his bumper at only a 5 or 10 mph closing speed. Hold your wheel straight and you'll be okay. This is common knowledge in NASCAR, where they close draft at 200 mph. Your post represents the hysteria I'm trying to counter with my response. I'm not trying to encourage people to close draft. I'm saying it isn't such a big deal and I'm offended by the infusion of political correctness into a pure sport that has proved harmless over 40 years of practice. Real hypermilers should defend close drafting, not condenm it. Look at the title of this thread, Wanted: Documentation of Dangerous Drafters. Well? Where is it?

    3)
    Not true. As you ease through the turbulence into the vacuum zone, you will notice that your foot lifts noticeably from the gas pedal. This is because you are no longer pushing air out of your way. The truck is doing that for you. And professional truck drivers like me maintain a constant speed. You've obviously never done close drafting.

    4)
    People often think turbulence is all drag. That's not true. When hypermiling in turbulence, drag is for the most part generated by the wind vectors that come from the forward quadrants. But while the overall drag is reduced in the turbulent wake of a truck, the major benefit lies in close drafting.
     
    Last edited: May 14, 2010
  16. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Ptero, have you considered what happens if the truck driver loses concentration and happens to slam into something you can't see because you are too close? Or straddles road debris you can't see because you are too close? Or has a tire blow out and you can't avoid it because... you are too close?

    This isn't hysteria, it is an objective look at the danger factors involved. Having tried this myself :)o) I know from experience what the activity can and cannot do for me. I can achieve low 50's on the highway in my Elantra with P&G drafting. I can achieve over 60mpg on the highway at lower speeds using P&G without any drafting at all. I'll stick with the one that gives me higher mileage and fewer hazards, thanks.

    Once again, I'd sure hate to see you lose your life to something that could easily have been avoided with a bit of anticipatory focus. After all, that's the key to hypermiling -- choosing the best technique while keeping situationally aware of the environment as far out as possible. It is hard to see much of anything with a huge trailer blocking forward view, and just as hard to keep an eye to the rear if all your attention is required to avoid running into that large bumper which just happens to be at about eye level. :(

    No one here claimed you can't get positive effects on fuel economy from drafting. We just state (with facts to back it up) that you can get better mileage much more safely by using other techniques.
     
  17. lightfoot

    lightfoot Reformed speeder

    Human visual reaction times are on the order of 100-200milliseconds, not 1ms. See http://www.humanbenchmark.com/tests/reactiontime/stats.php. At 65mph one travels 10-20 feet in this time.

    This table omits the data the MythBusters got at 2 feet. At 2 feet, the reduction was 28%, or about the same as at 20 feet, because "Grant [the driver] had to keep working the car pedal to maintain distance from the truck." Even at a constant 55mph.

    There's no question that it reduces drag. It's just WAY too dangerous.

    Very sensible of them. So what do you do to improve FE when you have a passenger and don't close draft?

    Looking back at the posts, it appears that
    (a) there are so few actual drafters and it is so hard to determine if someone is drafting or simply tailgating (can't know what their intentions are or see if their left foot is on the brake!) that nobody has photos of them
    (b) there are many tailgaters, so the thread turned to documentation of dangerous tailgaters
    (c) the title of the thread was sarcastic: few people draft for fuel economy whereas lots of people drive dangerously close (tailgate) because they're distracted, frustrated, or just don't drive well.

    Great: you've just had a 5-10mph collision (not insignificant) and you're still traveling at ca 55mph while you try to deal with that, meanwhile your forward vision is blocked by the back of the truck in your face. No thanks. This situation is completely different from a parking lot collision at 5-10mph.

    Not to mention that any road debris that the truck has straddled ISN'T moving at 65mph, so you have full closing speed with that. No chance to reduce impact by braking to scrub off 10-20mph before you hit it, or better yet avoid it.

    I spent 10 years as a professional photographer working trackside at ovals like Daytona, Texas Motor Speedway, and Charlotte, not to mention at most major road circuits in the US and Canada. I witnessed a LOT of crashes (and lots of drafting). There are HUGE differences between these environments and normal roadways in terms of the crashworthiness of vehicles, driver protection, runoff areas and protected crash zones, instant availability of medical personnel, etc, etc. Besides, racing and safe, economical travel are two completely different mindsets (or should be).

    Not in traffic and not on the rolling terrain around here. Even in the MythBusters episode when the truck was moving at a steady 55mph the car driver had to work the accelerator to maintain distance.

    A drafter must follow the truck's speed pattern, which is probably too fast (even these days) and doesn't match what is best for FE for a car. A drafter can't glide the downhills because he can't see them coming and because he must either brake to avoid hitting the truck or gas it to keep up. A drafter can't glide approaching a traffic slowdown because he can't see it. And on a flat roadway there is no way a drafter can reap the huge benefits of P&G.

    Read my post: I've drafted at inches or less on a bicycle (our front tires used to scuff the taillight on the scooter we were drafting behind, and I was often inches behind trucks). And I tried drafting - close but not inches - on a motorcycle (for warmth) and in my car.

    Yes and no. Yes, in the turbulent area behind a truck the car's pressure drag is reduced. But surface drag is increased. In smooth air, a boundary layer of air sticks to the car (if it's well designed) so that we have air:air friction, which is far less than air:surface friction. Turbulence destroys this boundary layer. In close-in drafting, there is very little air flow because one is in a pocket of still air traveling with the truck.

    Even setting aside the huge safety issues, close-in drafting isn't a good tactic for saving fuel because (a) slowing down to 50-55mph will save more fuel than drafting a truck at 65mph and (b) the huge benefits of gliding, P&G, DWL, etc aren't available when you're glued to the back of a truck.

    P.S. Thanks for your posts: it always helps to keep rethinking issues like this.
     
    Last edited: May 14, 2010
  18. Xringer

    Xringer Older Member

    Maybe it would be safer to draft behind one of these Gator Getter trucks?

    [​IMG]
    http://www.gatorind.com/

    Then, you won't have to worry about hitting one of these.
    [​IMG]

    When you drive across country in the summer time, you can hear the drivers
    warning each other about the 'Gators' on the CB. Even big-rigs don't want to hit them.
    If you hit one just right, you can launch it into the air, to break some windshields behind you.

    Unfortunately, there are millions of gators (and other debris) on the roads just waiting
    to nail some inattentive driver.

    I've seen objects like sheet metal fall off trucks and then fly around like pin-balls
    as it clipped cars traveling behind the truck.

    In the winter time, almost everyone around here knows about the giant sheets of ice that fly off the tops of trailers.
    No one wants to be around when one of those comes down.

    Now that I'm an old man, I seem to have lost my one millisecond reaction time.. :rolleyes:

    Yeah, I'll stick to driving with one foot and a clear view of the road ahead.. :cool:
     
  19. Chuck

    Chuck just the messenger

    ....and typically you don't post like this late at night when the spammers and flamers are most active - not saying you are one of those, but pointing out the unsavory company that hates to post when everybody else is present.

    Like a rolling stop thru intersections, it's a bad idea for both gearhead and hypermiler.

    It goes on to mention hypermilers as tailgaters....if you are serious, get that edited out of the Wikipedia article. Many of us have edited Wikipedia articles before.

    Three years ago I found being a few feet behind a semi way too close to take see and take and exit in time.

    Ptero, you have dodged the PR hell this practice has brought. I can't count the articles the media discredits hypermiling because they draft in the manner you are advocating. Part of what we are wanting to do is to encourage the general public to save gas....it's not just about how much I save but getting others to save.

    Ptreo, how is embracing your practice going to increase the number of drivers that drive for economy? We look forward to your answer along with your efforts to remove hypermining from Wikipedia's tailgating article. Saying this because I hope you are looking for more than a mere reaction to your posts.
     
    Last edited: May 14, 2010
  20. Ptero

    Ptero Hydrogen Nut, Battery Skeptic

    Chuck, you're rambling.

    Here's a radar braking technology from Mercedes. I heard that they ran a test by equipping a series of trucks with this technology and running several hundred kilometers nose-to-tail while experiencing dramatic fuel savings.

    Note that the accidents mentioned all have high closing speeds and were not due to drafting. I cannot find any statistics about drafting accidents. And I've never seen one. Can't even find any mention of drafting on the National Highway Traffic Safety Administration (NHTSA) where they do talk a lot about real problems.

    In fact, when I'm trying to drive at a sensible speed on interstates, I'll pull behind a governed truck as a survival strategy. I can't be sure the leadfooted yahoos will see my little plastic car but they always seem to see the truck I'm drafting. I'm a lot more worried about one of them running into the back of me than I am about me running into the back of the truck I'm drafting and maybe scratching my paint..
    _________________

    [​IMG]

    DISTRONIC PLUS and Brake Assist PLUS – Mercedes assistance systems based on sophisticated radar technology – are highly effective at helping to prevent accidents. This is one of the findings of an analysis carried out by Mercedes-Benz based on representative accident-research data. This technology can prevent a fifth of all head-to-tail crashes in Germany alone. On motorways, the accident rate can be reduced by as much as around 36 percent. Mercedes-Benz has further enhanced the radar technology for the new E-Class and 2009 S-Class.

    Every year in Germany there are over 50,000 serious head-to-tail crashes, in which some 5,700 people are either killed or seriously injured. One in six traffic accidents in which people are injured is down to a head-to-tail crash. The situation is even more serious in the US, where this type of collision accounts for around 30 percent of all serious road accidents.

    In developing the DISTRONIC PLUS and Brake Assist PLUS radar-based assistance systems, which have been available for the S-Class since 2005 and the CL-Class since 2006, Mercedes-Benz has made an important contribution towards preventing head-to-tail crashes. This is one of the findings of the latest accident research carried out at Mercedes, based on the reconstruction of over 800 head-to-tail crashes. The representative study focussed on one question in particular: how many accidents of this type could be prevented if all passenger cars were equipped with this Mercedes technology?

    The results confirm the considerable safety-enhancing effect of the assistance systems: DISTRONIC PLUS and Brake Assist PLUS prevent over 20 percent of head-to-tail crashes on average. In another quarter of these collisions, the systems can help to greatly reduce accident severity. This combination of state-of-the-art radar and brake technology offers the greatest safety potential on motorways, where around 36 percent of all head-to-tail crashes can be prevented.
    http://www.daimler.com/dccom/0-5-1210218-1-1210321-1-0-0-1210228-0-0-8-7165-0-0-0-0-0-0-0.html

    [​IMG]

    An EU-financed research project is looking at inexpensive ways of getting vehicles to travel in a 'platoon' on Europe's motorways.
    Each road train could include up to eight separate vehicles - cars, buses and trucks will be mixed in each one.
    The EU hopes to cut fuel consumption, journey times and congestion by linking vehicles together.

    Early work on the idea suggests that fuel consumption could be cut by 20% among those cars and trucks travelling behind the lead vehicle.

    Spanish trials

    The lead vehicle would be handled by a professional driver who would monitor the status of the road train. Those in following vehicles could take their hands off the wheel, read a book or watch TV, while they travel along the motorway. Their vehicle would be controlled by the lead vehicle.

    Funded under the European Commission's Framework 7 research plan, Sartre (Safe Road Trains for the Environment) is aimed at commuters in cars who travel long distances to work every day but will also look at ways to involve commercial vehicles.
    Tom Robinson, project co-ordinator at engineering firm Ricardo, said the idea was to use off-the-shelf components to make it possible for cars, buses and trucks to join the road train.




    "The goal is to try and introduce a step change in transport methods," he said.

    "We're looking at what it would take to get platooning on public highways without making big changes to the public highways themselves," said Mr Robinson.

    A system that involved wiring up motorways with sensors to help control the road trains would be prohibitively expensive, he said.

    "Each of the vehicles will have their own control and software monitoring system," said Mr Robinson. "There may well be a platoon sensor envelope that collates information and presents it to the lead vehicle so it can understand what is happening around all the vehicles."

    The idea is to make platoons active so vehicles can join and leave as they need. Mr Robinson speculated that those joining a platoon or road train may one day pay for the privilege of someone else effectively driving them closer to their destination.
    Sartre will run for three years. The project partners are currently doing preliminary research to find out all the elements needed for a working system and the situations in which it might be used.

    There were also behavioural elements to consider, said Mr Robinson, such as whether all the vehicles will need to have their hazard lights on while in a platoon.

    Also, he said, there had to be a way to ensure the vehicles in a platoon are organised to make drivers feel safe.

    "Car drivers do not want to be between trucks," he said.

    Towards the end of the research project trials will be held on test tracks in the UK, Spain and Sweden. There are also plans for public road trials in Spain. The first platoon will involve two trucks and three cars.
    http://news.bbc.co.uk/2/hi/technology/8349923.stm
     
    Last edited: May 16, 2010

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