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.
[INAUDIBLE]. [SOUND] [MUSIC] 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 now getting ready to measure the truck. We have the trucks set up here and the truck is set up at a 90 degree angle, the aerial is 90 degrees to the chassis, and it's at 0 degree elevation. As you can see, this is the most room that the truck could 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 fire fighters who are going to measure the truck for us. We are going to start with the aerial first. You're going to take a measurement from the side of the chassy to the further most point of the aerial. With a truck like this, it should be in the neighborhood of about 30 to 32 feet. Its a 4 section area in each section is, is about 20 to 24 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 to 30 foot tape that were using today, it was 30 feet up to about,. The middle of the ladder pipe, and now we're going to get to the rest of that. And we have a measurement of? >> 32 feet. >> 32 feet, okay. So we're 32 feet, we're at the high end, the next measurement that we're going to take, is that we're going to have to measure the chas. If you go to a downtown row of stores in a tight space, and you aren't going to anticipate using your truck at around a zero to ten degree angle, you're going to need at least this much room in order to set the truck. Here, we have our firefighters measuring the truck. Now and generally this measurement should be somewhere between eight feet and about eight, four. There's a DOT regulation here that the manufacturers 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 that eight feet, three inches. 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 three inches, at a minimum. Now, if you're going to set the truck up totally, we're gonna need a little bit more real estate to do that. And so we measure this jack, realising that the other jack would be out on the outside of the truck. And once the measurement of that. Four feet five and a half inches. So, the maximum operational footprint of this apparatus then would be 45 feet, 9 inches. 45'9". So that's the maximum footprint if you were to shortjack the outboard side and bring the jacks in. We could subtract this measurement and then we would add the 8'3" and, the 32' and the minimum footprint for this vehicle, then would be 40'3". Realizing that most apparatus today can be short jacks, however, there are a couple of manufacturers. Due 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 gonna 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 aerial 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. And 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 areal down to the ground and subtract it from the 100 foot that this areal is rated for. And that measurement, in this case, ended up being 7 foot 6. 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 chassé out of that number and it's 100 feet less 7 foot 6 or we will be able to reach at zero degrees. On a horizontal plane 92 feet 6 inches. But it's not just 92 feet 6 inches this way to the right. We can also reach 92 feet, 6 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 these calculations we would realize that this aerial at zero degrees could reach about 170 feet of any gives building at zero degrees at one story row of stores now we have completed the measurement of a 100 foot aerial ladder we are now going to turn and measure a 95 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. The next stop [UNKNOWN] we're gonna measure is a 95 foot mid mounted C grade for 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 in this particular apparatus that from the bottom of the boom to the ground the amount that we are going to have to subtract out of that 95 feet is going to be less than the 100 foot truck that we did so we are going to start the same way to calculate the operational footprint of this vehicle and we are going to 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 chassis out to 32 feet. The aerial ladder is a hundred feet. It has four sections. This is a four-section aerial scope tower and the measurement is. The measurement is 24 feet, six inches. As you can see, it is dramatically less than the 32 feet for the C-grade, 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 eight feet. And eight foot six inches due to DO2 regulation for over the road width. And the measurement is, the measurement is eight feet two inches. So if we take the 24 feet and the eight feet and add the inches, we're gonna find out that this, the minimal operational footprint for this vehicle if we short jacked it. Is gonna be around 33 feet. Recalling earlier, the rear mounted 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 minimum footprint is far less than the rear mounted area. 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 eight 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. 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 40 feet and far less than the operation footprint of the rear mounted tower. And we often get asked the question what has the best scrub area? And understanding that scrub area 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 aerial ladder. And scrub area is depending 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 the second thing to consider is how it was positioned on the fire ground ready for firefighting duty. In this case, the squadburry of this vehicle based on design, are you going to find, is going to be, pretty good. So, to wrap up here, you can see that calculating the operational flip point of the vehicle and finding what's going to best suite your area as it relates to room, to be able to set the truck up, is gonna be a vital importance as you go to purchase the truck and as you go and use the truck in your first do. For fire engineering and training minutes, this is Mike Wilbert. [SOUND]