Tanker 'Roll overs':

[1OLDTIMER]

Ashley, Indiana Fire Dept. pumper truck rolls!!

This is a few months old, however I think it may be a good 'training' tool for drivers.

Cause could be driving too fast...not considering the sudden 'shift' of the H2O the tank when conering.

http://www.youtube.com/watch?feature...&v=ksFNWl3QidQ


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Here is another recent tanker 'roll over'

Tuesday, March 20, 2012 Emergency crews responded to an overturned fire truck Monday afternoon in Madison County, Miss.

http://www.emergencyvehicleresponse....ayoutfile/home

[johnsb]

Good topic. I've seen where a lot of old heads have even rolled a tanker. Good reminder that we all need to keep up on training.
We are recieving a new engine/tanker around the first of August. We will require driver/operator training before FF's can drive it on a run. I'm thinking there will be about 5-6 hours required before a driver is qualified. It will also be the last truck they qualify to drive, as it will be the biggest. There's four other trucks they have to qualify on first, not counting our grass truck.

[EastKyFF]

I'm not happy with the configuration of that truck. It looks like a very high center of gravity, and a rectangular tank exacerbates the problem. It does look like speed is a factor too.

On a side note, I was really touched to see all the civilians running over to help. You see so many videos and photos these days of people not willing to get involved, so it's nice to see Small Town USA acting this way. I hope the crew is OK.

[johnsb]

I'm not happy with the configuration of that truck. It looks like a very high center of gravity, and a rectangular tank exacerbates the problem. It does look like speed is a factor too.

On a side note, I was really touched to see all the civilians running over to help. You see so many videos and photos these days of people not willing to get involved, so it's nice to see Small Town USA acting this way. I hope the crew is OK.

I'd say as new as that tanker is, some engineering went into it as far as the center of gravity. But regardless of that, excessive speed will overcome center of gravity no matter how low it is.

[firepundit]

I'm not happy with the configuration of that truck. It looks like a very high center of gravity, and a rectangular tank exacerbates the problem. It does look like speed is a factor too.

Please explain why you think a rectangular tank would exacerbate the problem. It would seem to me that a properly baffled rectangular tank would have a lower center of gravity than most tank shapes that are also properly baffled.

Physics being physics, I am interested in your slant on things.

[ChiefKN]

Speed...

Regardless of other factors, slowing down would've prevented this.

I always tell the guys that there is just no urgent need for the tanker. It gets there when it gets there.

[kuh shise]

Tanker Rollover

Looking at the video, I made some measurements and calculations as follows:

1. The video timer is real time and correct.
2. Roadway is 24 ft. from curb to curb and the distance from curb to centerpoint of the radius is another six feet giving a radius of curvature of 30 feet.
3. It takes the truck six seconds to round the curve of 188 ft (1/4 circumference)
4. The truck is traveling at 31 feet per second or 21 MPH
5. The acceleration will be velocity squared divided by the radius 31 x 31 / 30 = 32 ft/sec squared
6. Acceleration divided by 32 ft (1 G) or 32 / 32 + 1G so the radial force will be equal to the weight of the truck
7. Next question is..Where is the center of gravity compared to the width of the wheelbase.
8. I used the picture standing still and estimated the height at 110 inches at top of tank
9. Looking at the picture my guess is the center of gravity is about 70 inches above the roadway.
10. Width of the wheels is around 100 inches, so the pivot point is 50 inches from the center of gravity. (looking directly at the rear of the tanker.) It will take a force of 50 / 70 G’s to turn this truck over. This is 0.707 G for this turn.
11. Reversing the calculations The maximum speed for this curve would be 26 ft / sec or 18 MPH.
12. If the car were not in the intersection, and the driver spread the curve by coming to the inside in the middle of the turn (making the curve longer) the radius could be stretched to a 40 ft radius. This would result in 0.75G or just slightly above the turn over point. He was still too fast for the turn.
13. This tanker illustrates why the center of gravity is a critical specification on heavy apparatus. Tankers, aerials, cranes, etc. Slow it down! 20 MPH seems like a crawl after you have been running at 40 or more on the straight away.

[1OLDTIMER]

Please explain why you think a rectangular tank would exacerbate the problem. It would seem to me that a properly baffled rectangular tank would have a lower center of gravity than most tank shapes that are also properly baffled.

I don't know for sure, but how many 'other type' of tank vehicle(s) do you see with rectangular tanks...i.e., petro, milk etc, must be good reason...?

[ChiefKN]

I don't know for sure, but how many 'other type' of tank vehicle(s) do you see with rectangular tanks...i.e., petro, milk etc, must be good reason...?

A rectangular tank on its own is no more dangerous than a round or elliptical tank.

It is ALL about the baffles and center of gravity.

Many milk tankers have NO baffles for sanitary (sterlizing) reasons.

[johnsb]

I don't know for sure, but how many 'other type' of tank vehicle(s) do you see with rectangular tanks...i.e., petro, milk etc, must be good reason...?

Milk and gas tankers don't carry ladders, 5" hose, dump tanks, etc. The reason for square tanks is to accommodate more equipment. Elliptical tankers sacrifice storage space for water capacity.

[1OLDTIMER]

Milk and gas tankers don't carry ladders, 5" hose, dump tanks, etc. The reason for square tanks is to accommodate more equipment. Elliptical tankers sacrifice storage space for water capacity.

Thanks, but I guess THIS is what I had in mind as a 'tanker', and it looks like it has a elipitical tank, a dump tank, with a good size pump, etc., but I cannot see why a (real) tanker has a need for ladders.

However, I was ref; to a tanker not a tanker/pumper. Maybe I am not on the same page...as usual...

[LaFireEducator]

Thanks, but I guess THIS is what I had in mind as a 'tanker', and it looks like it has a elipitical tank, a dump tank, with a good size pump, etc., but I cannot see why a (real) tanker has a need for ladders.

However, I was ref; to a tanker not a tanker/pumper. Maybe I am not on the same page...as usual...

Attachment 21946

In LA, many rural departments use the storage space afforded by a rectangular tank for stuff - saws, airpacks, spare cylinders, salvage covers, fans, pike poles and ladders - so that it can be claimed as a service truck on the rating.

[donethat]

The recent 2009 edition of NFPA1901 requires that if a tanker, or any truck for that matter, cannot make a 50% tilt table test, the chassis must be equipped with electronic stability control. That may not have prevented this particular accident but it would have raised the threshold at which it occured.
As a result, more tankers look like the attached version with a long low tank and the water pump located under the water tank for a lower center of gravity.

[johnsb]

Thanks, but I guess THIS is what I had in mind as a 'tanker', and it looks like it has a elipitical tank, a dump tank, with a good size pump, etc., but I cannot see why a (real) tanker has a need for ladders.

However, I was ref; to a tanker not a tanker/pumper. Maybe I am not on the same page...as usual...

Attachment 21946

Well I'm probably a bit biased right now because we just bought a pumper/tanker, but if we had a larger district without any hydrants, that truck would be nice to have!

[LFD2203]

Tanker Rollover

Looking at the video, I made some measurements and calculations as follows:

1. The video timer is real time and correct.
2. Roadway is 24 ft. from curb to curb and the distance from curb to centerpoint of the radius is another six feet giving a radius of curvature of 30 feet.
3. It takes the truck six seconds to round the curve of 188 ft (1/4 circumference)
4. The truck is traveling at 31 feet per second or 21 MPH
5. The acceleration will be velocity squared divided by the radius 31 x 31 / 30 = 32 ft/sec squared
6. Acceleration divided by 32 ft (1 G) or 32 / 32 + 1G so the radial force will be equal to the weight of the truck
7. Next question is..Where is the center of gravity compared to the width of the wheelbase.
8. I used the picture standing still and estimated the height at 110 inches at top of tank
9. Looking at the picture my guess is the center of gravity is about 70 inches above the roadway.
10. Width of the wheels is around 100 inches, so the pivot point is 50 inches from the center of gravity. (looking directly at the rear of the tanker.) It will take a force of 50 / 70 G’s to turn this truck over. This is 0.707 G for this turn.
11. Reversing the calculations The maximum speed for this curve would be 26 ft / sec or 18 MPH.
12. If the car were not in the intersection, and the driver spread the curve by coming to the inside in the middle of the turn (making the curve longer) the radius could be stretched to a 40 ft radius. This would result in 0.75G or just slightly above the turn over point. He was still too fast for the turn.
13. This tanker illustrates why the center of gravity is a critical specification on heavy apparatus. Tankers, aerials, cranes, etc. Slow it down! 20 MPH seems like a crawl after you have been running at 40 or more on the straight away.

I agree with KuhShise: Pilot Error.

[firepundit]

I don't know for sure, but how many 'other type' of tank vehicle(s) do you see with rectangular tanks...i.e., petro, milk etc, must be good reason...?

Over the road trucks use oval or round tanks because they are easier to build and less seams. It has absolutely nothing to do with center of gravity. For any given capacity and a fixed length, the oval or round tank will have a higher center of gravity.

[firepundit]

Found some information on the DOT website that pertains to rollover accidents. It comes from a study of tank truck rollovers that was released May, 2008.

Over 1,300 cargo tank rollovers are reported each year.

31% of all fatal commercial truck rollovers involve cargo tanks.

93% of cargo tank rollovers occur on dry road surfaces.

Over 50% of cargo tank rollovers involve leaving the road.

28% of cargo tank accidents involve driving too fast for conditions.

44% of cargo tank rollovers occur on curves (56% on straight roads.)

25% of cargo tank rollovers involve straight trucks.

66% of cargo tank rollovers involve drivers with more than ten years driving experience.

78% of cargo tank rollovers involve some kind of driver error.

[1OLDTIMER]

Found some information on the DOT website that pertains to rollover accidents. It comes from a study of tank truck rollovers that was released May, 2008.

Over 1,300 cargo tank rollovers are reported each year.

31% of all fatal commercial truck rollovers involve cargo tanks.

93% of cargo tank rollovers occur on dry road surfaces.

Over 50% of cargo tank rollovers involve leaving the road.

28% of cargo tank accidents involve driving too fast for conditions.

44% of cargo tank rollovers occur on curves (56% on straight roads.)

25% of cargo tank rollovers involve straight trucks.

66% of cargo tank rollovers involve drivers with more than ten years driving experience.

78% of cargo tank rollovers involve some kind of driver error.

Good data. I find this VERY interesting, especially that 78% involve (some type of) 'driver error', and that 93% occur on 'dry' road surfaces.

I wonder if this equates to; not paying attention, and not considering the weight/height of the vehile while cornering or exiting on ramps? A less than full tank (like when returning) will overturn easier than a when full.

[johnsb]

Good data. I find this VERY interesting, especially that 78% involve (some type of) 'driver error', and that 93% occur on 'dry' road surfaces.

I wonder if this equates to; not paying attention, and not considering the weight/height of the vehile while cornering or exiting on ramps? A less than full tank (like when returning) will overturn easier than a when full.

I think the real interesting stat is that 66% of rollovers had drivers with more that 10 years experience. I thought that number would be the other way around.

[firepundit]

I think the real interesting stat is that 66% of rollovers had drivers with more that 10 years experience. I thought that number would be the other way around.

How about the incidental 56% that occur on straight roads? Over half. That one got me.

My understanding is that that, predominately, the right front wheel left pavement and drivers over-corrected when returning to the pavement. You should come back on in an oblique angle regardless of the damage to your tires as they scrub on the side. To be honest, I just couldn't read the whole report so they might have reached different conclusions at the very end.