Drafting a big rig

[user removed]

Traffic Cameras | HamptonRoads.com | PilotOnline.com

First point. I do not actively seek a drafting situation.

Second point, if you check some of the traffic cameras on the above posted link, especially the bridge tunnel to the right (Hampton Roads Bridge Tunnel), which was built (first tunnel) in 1957, during rush hours, you will better understand that you really have no choice under certain situations.

In fact, inside the tunnel itself, where there is no lane changing and no escape route, notice how close the average distance between vehicles can get at the peak traffic volume times.

In summer (tourist season) the density is something like 95,000 vehicles per day for east or west bound lanes. I think that is 95k in each direction. That's 45,000 per lane, per day, with a day at 84,600 seconds.

Do the math. That's less than 2 seconds average, for every vehicle, for 24 hours. When the peak congestion periods come, it's much less than 2 seconds per vehicle.

You can try to leave a 3 second (football field length) space between you and the car in front of you, and all you will do all day long is hit your brakes as someone pulls over 20 feet in front of you, and if you are in the center lane of a 3 lane section of road, you risk as simultaneous merge by drivers on both sides, with a collision right in front of you at 65 MPH, with a half a dozen cars within 300 feet behind you times 3 lanes.

It's not uncommon to look in your mirror and see nothing but a pickup truck grille in your mirror.

I try to avoid the Interstates here, because people are stupid and don't know how to drive. You would think that they learned by watching a NASCAR race.


regards
Mech

[Chuck.]

Please, please don't draft!

I can't tell you how many hypermiling stories imply that "all hypermilers draft 18-wheelers and roll thru intersections" :mad Of course it's seldom practiced, but the media enjoys spreading this misinformation. The effect is the general public is turned off by hypermiling, even when most techniques are nothing like this.

Aside from obvious safety issues, you are likely not to see an exit until it's too late. Most truckers know when they are being drafted and will shake you off. And this is outside of the city - the only place you can get an opportunity to do this.

[Chalupa102]

Originally Posted by Chuck.

Please, please don't draft!

I can't tell you how many hypermiling stories imply that "all hypermilers draft 18-wheelers and roll thru intersections" :mad Of course it's seldom practiced, but the media enjoys spreading this misinformation. The effect is the general public is turned off by hypermiling, even when most techniques are nothing like this.

Aside from obvious safety issues, you are likely not to see an exit until it's too late. Most truckers know when they are being drafted and will shake you off. And this is outside of the city - the only place you can get an opportunity to do this.

Completely agree. The media is all about trying to attack hypermilers and say that what we do is "dangerous". I also have a friend who is a trucker driver. He is mainly referring to the aggressive/road raged drivers, but he said that he absolutely hates when people follow too close.

[roflwaffle]

Originally Posted by ilusnforc

If you are 130 ft behind a vehicle that begins braking and it takes you 130 ft to react and begin braking as well, you will begin braking at approximately the same point as the vehicle in front of you, if you have better braking capability or shorter stopping distance you will still be well behind that vehicle when stopped as the vehicle in front of you will be incapable of an instantaneous stop (except in the instance of something influencing the abrupt stopping of the vehicle in front of you such as the already mentioned reinforced wall, car hitting a stopped big rig, etc).

Assuming that average human reaction time from seeing a situation to applying brakes takes 130 ft, I'd say that 130+ ft is safe for a following distance.

The problem there is that if the average is 130 ft before someone starts to brake, then some people will be above average and fine, and another large chunk will be below average and tap the semi on the rear. Having a safety margin is never a bad idea AFAIK, which is why we have the three second rule like you mentioned instead of a two second rule even though on average may be able to respond in two seconds.

[caissiel]

Me and the Mrs travelled to Florida from canada, 1800 Miles. I drove the RV, Ford F250 with a 15000Lbs 5th wheel trailer in tow. My mrs had the Toyota Matrix 1.8L engine 5 Speed.
I averaged 13.4 MPG on the trip. But the best was my Mrs with the Matrix. She averaged 45MPG on the 1st 2 tanks following me. I then told her to back off a bit from me until she felt the need to lift the accelerator a bit and stay there for most of the rest of the trip. The next 2 tanks of Gas were at 49MPG. I drove at 100KPH or 63MPH most of the way and all the traffic just passed us and left her behind me. We did the trip back for Christmas and we did average 40MPG, that was the car alone the RV is still in Florida. We travelled faster on the way back because any day I can do 45MPG with the Matrix at 100KPH. The MPG are in Imperial which is 6/5 of a US Gallon.

[discovery]

Driving very close behind a big rig with Honda Insight at 80 mph you can get well over 80/85 mpg on the instant dash board computer. At night with no big rig in front same highway MPG sucks alot.

[justjohn]

How close it's safe to follow all depends on your reaction time and how attentive you are. I'll be one of the first to say drafting as a habit is probably a bad idea.

However, considering the difference in stopping distance between a fully loaded semi and any car with decent brakes, an intensely alert driver with decent reaction times can follow significantly closer than 3 seconds.

To me the question is more about other risks, (like tires coming off) and whether you're willing to stay on edge to keep it safe than it is about stopping distance.

[Jethro]

I hate being behind Semi's period. In NM I guess they don't use enough tar when they pave, so seems every Semi throws an ungodly amount of rocks up. Windshields are expensive.

I'll either be WAY behind one, or pass em. Period. Drafting is fun when it's your buddy driving infront of you, but drafting a stranger is a HORRID idea.

[Bicycle Bob]

Here ya go: Robot drafting: Follow the leader: SARTRE road train technology successfully demonstrated

[AeroModder]

The images show it being used in the slow lane, which would be very dangerous for someone realizing that they need to take an exit that the "train" is blocking. That should be used in the far left lane only.