Wed, 8 Feb 2012|
Lieutenant Mike Wilbur of the Fire Department of New York (FDNY) compares the operational footprint of an aerial ladder to a tower ladder.
[NOISE]. Hi, I'm Mike Wilbur. Welcome to Fire Engineering Training Minutes. Today, we're going to determine the operational footprint of both an aerial ladder and a tower ladder. Okay, we're not getting ready to measure the truck. We have the truck set up here. And the truck is set up, at a 90-degree angle. The aerial is 90-degrees to the chair seat. And it's at zero-degree elevation. As you can see, this is the most room, that the truck can potentially take up. If you take the aerial and put it up at an angle, obviously, the footprint, of the truck, will shrink. Now I have a couple of assistant firefighters who are going to measure the truck for us. We're going to start with the aerial first. You're going to take a measurement from the side of the chassis out to the furthest most point of the aerial. With a truck like this, it should be in the neighborhood of about 30 to 32 feet. It's a four section, aerial, and each section, is, is about twenty-two, twenty-four feet, in length. You can see that the tape is a little short, we're going to come together and get the rest of that. it's a thirty foot tape that we're using today. It was thirty feet up to about. The middle of the ladder pipe and now were gonna get to the rest of that. And we have measurement of >> 32 feet. >> 32 feet. Okay so were at 32 feet. Were at the high end. The next measurement that were going to take is that were going to have to measure the chairs. If you go to a down town row of stores in a tight space and you are going to anticipate using your truck at around a zero to 10 degree angle you're going to need at least this much room in order to set the trucks. Here we have our firefighters measuring the truck. On now and generally this measurement should be somewhere between eight feet and about eight four. There's a DOT regulation here, that the manufactures have to subscribe to so, that the truck isn't over width. And we get a measurement of, >> Eight feet three inches. >> Eight feet three inches. And so what we're going to do now is, we're going to add 32 feet. And then we're going to add 8'3". And we realize that if this truck was short jacked with only the set of jacks on the inboard side of the truck out, that it would take, at a minimum, the operational footprint of this truck. Would be 40 feet, 3 inches at a minimum. Now if your going to set the truck up totally we're going to need little bit more real estate to do that and so we measure this jack realizing that the other jack would be out on the outside of the truck. And what's the measurement of that. 4' 5.5" >> 4' 5.5". So the maximum operational footprint of this apparatus then would be 45' 9". 45' 9". So that's the maximum footprint if you were to short jack the outboard side and bring the jacks in. We could subtract this measurement and then we would add the eight feet three inches and the thirty two feet and the minimum for this vehicle then would be forty feet three inches. Realizing that most apparatus today can be short jaxed however there are a couple of manufactures that. Do to constraints, don't allow that to occur. And so, if you were to measure that particular vehicle, you would just have the maximum footprint. Because all the jacks would have to be out, all the time. The next measurement that we're going to take on this 100-foot rear-mount ladder, is a measurement from the bottom of the aerial-ladder, down to the ground. American Aerial ladders, the distance that they can reach is calculated from the tip of the areal down to the ground. Many US cities use their aerials in a vertical plane. But most of the rest of the country use their aerials in more of a horizontal plane for reach. So in order to get an accurate accounting as to what the apparatus can reach, we need to subtract that measurement from the bottom of the aerial down to the ground and subtract it from the 100 foot this aerial is rated for and that measurement in this case ended up being seven foot six. So at a zero degree angle like you see the apparatus here now, we can use this apparatus. It won't reach 100 feet. We have to subtract the chassis out of that number. And it's a 100 feet less 7 foot 6, or we will be able to reach at zero degrees. On a horizontal plane, 92 feet, six inches. But it's not just 92 feet six inches this way, to the right, we can also reach 92 feet six inches to the left. But that would be, That would be calculated if we had the aerial right up against the building line, but we know that we can't be in the collapse zone and we have to have the aerial away from the building line, and so we're going to make an allowance for that about one boom length, which, again, we calculated to be 32 feet away from the building. And when we get all done with this calculations, we would realize that this aerial at zero degrees could reach about a hundred and seventy feet of the frontage of any given building at zero degrees a one story row of stores. Now we've completed the measurements on a hundred foot aerial ladder. We are now going to turn and measure a ninety-five foot mid-mounted aerial tower. And as you will see here, the measurements are gonna be vastly different as it relates to the operational footprint. [MUSIC] The next apparatus we're gonna measure is a 95 foot mid-mounted C grade aerial scope tower ladder. As you're going to see here, it's going to be vastly different than the rear mounted aerial ladder that we did previously. One of the issues with this as we measure is the geometry as it relates to the turntable to the ground. You are going to see this particular apparatus, that from the bottom of the boom down to the ground, the amount that we're gonna have to subtract out of that 95 feet is going to be far less than the 100 foot truck that we did. And so we're gonna start the same way to calculate the operational footprint of this vehicle. And we're gonna measure from the side of the chassis. Out to the tip of the boom. As you recall from the earlier, segment. That the, aerial ladder had a measurement from the side of the chassé out to 32 feet. The aerial ladder's 100 feet. It has four sections. This is a four section aerial scope tower and the measurement is. The measurement is 24 feet, 6 inches. As you can see, it is dramatically less than the 32 feet for the Seagrave rear mounted aerial. The next that we're going to calculate is the chassis. We need to get the chassis measurement. And that again should be somewhere between 8 feet. And 8'6" due to DOT regulation for over the road width. And the measurement is: the measurement is 8'2". So if we take the 24 feet and the eight feet and add the inches, we're gonna find out that this, the minimum operational footprint for this vehicle if we short jacked it,. Is gonna be around 33 feet. Recalling earlier the rear mounted aerial ladder, we had to add 32 feet plus the 8 feet, and we were over 40 feet for that truck. So the footprint for this, the mah, the minimum footprint is, is far less than with the rear mounted aerial. If we were to put both sets of jacks we would have to measure the jacks to account for that if we weren't going to short jack the truck, and so we'll measure those for you now. So so far we have a 24 feet plus a few inches and we have 8 feet plus a few inches, and so, we are at 32 feet and then we're going to add the jack in and the jack measurement is >> 6 4. Six four, so the outrigger on this truck is six feet four inches, and so we put everything together, and the operational footprint for this vehicle is gonna be less than forty feet. Again, far less than the operational footprint of the rear-mounted tower. And we often get asked the question what has the best scrub barrier? And understanding that scrub barrier is defined as that area of the building line that we can touch with the basket of a tower ladder or the tip of an area ladder. And scrub barrier's dependent on two very important things. Who did you buy the truck from, who built it? And then who designed the truck as it was being built. And then the second thing to consider is how it was positioned on the fire ground ready for fire fighting duty. In this case the scrub area of this vehicle based on design you're going to find is going to be, pretty good. So, to wrap up here you can see that calculating the operational footprint of the vehicle and finding what's going to best suit your area as it relates to room to be able to set the truck up is gonna be of vital importance as you go to purchase the truck and as you go to use the truck in your first do. For Fire Engineering Training Minutes, this is Mike Wilbert.