Introduction:
This document is meant to help you understand the math behind the MPC. The MPC is one of those amazing products that make it easy to get a result that's simple to calculate once you have the data but isn't simple to calculate in the real-world without FleetWatcher.
The Mainline Paving Calculator can help:
Optimize asphalt use by helping monitor asphalt-depth in real-time (the pictures below are about that).
Calculate how much more material will be required to reach the target for the day so that the right amount of material is ordered from the plant.
There are other things, but those are the high points.
1 square yard of asphalt, 1-inch-thick weights (for example) 110 lbs.
That’s a “square yard inch” often written “sy-in”
Therefore 1 square foot weights about 12.22 pounds
(110 pounds divided by 9 square feet in a square yard)
110 / 9 = 12.22
Therefore, if you’re paving 12 feet wide by 2-inch depth, then 1 foot of road weighs: 12.22lbs. * 2” x 12’ = about 293 pounds
Therefore, if you get a truck load of asphalt weighing 15 tons (30,000lbs) then that asphalt “should” cover 30000/293 = 102 linear feet.
Therefore, if FleetWatcher measures the paver using a 15-ton load in LESS than 102’, it is probably being laid down too thick.
Conversely, if FleetWatcher measures the paver using a 15-ton load in MORE than 102’, it is probably being laid down too thin.
Example: If, 1 ft = 293 lbs.
5280 feet in a mile
5280 feet X 293 lbs. = 1,547,040 lbs. of asphalt
2000 lbs. in a ton
1,547,040 lbs. / 2000 = 773.52 tons
So, it would take approx. 773.52 tons to pave a 1 mile stretch of road at 2" thick.
250 ft3 (from manufacturer specs)
Current material: 110lbs. per sy-in / 1.25 compaction ratio / 9 ft2 in a yd2 = 9.78
lbs. / sqft-in = 9.78 X 12 = 117.33 lbs. / ft3
250 X 117.33 = 29,333 lbs. = 14.66 tons
Set the hopper size and material density and FleetWatcher will do the math.
NOTE: Uncompacted material is 125% of the volume of compacted material which
means that compacted material is 80% of the volume of uncompacted material.
Shown as Math:
2.5” of uncompacted material *80% = 2” of compacted material
2” of compacted material * 125% = 2.5” of uncompacted material
Material To Finish 1:
Material To Finish 2:
Given a trend of 2.08” X 12’ wide @ 12.22 lbs. / sf-in, each linear foot is 305 lbs.
With 1800’ remaining, that’s 1800 X 305 = 549,000 lbs. (274.5 tons)
NOTE: The calculator also works by setting an end-time. For example, If it is 2:00 now and the user wants to stop paving at 4:00, and the trend is 15 FPM, FleetWatcher would calculate that in 120 minutes, 1800 more feet could be paved (120 * 15 = 1800) (minutes * FPM = Feet)
The purpose of % hopper full is to tell us how much is in the mat.
Asphalt Mat – During the laydown and compaction phase of construction, the asphalt mat is a term most used to refer to the new asphalt surface behind the paving machine.
Hopper. The hopper is used as a temporary storage area for HMA delivered by the transport vehicle.
At a high level, the hopper of a paver can be filled with the latest load and 20% of the prior load, if the paver has an 18 ton hopper and all the loads are approximately 15 tons. FleetWatcher calculates the hopper capacity in tons based on the user-entered material density (e.g., 110 lbs/sy-in) and the user-entered hopper capacity in cubic feet (ft³) in the Add/Edit equipment screen.
To illustrate this concept, let's assume that ten loads of 15 tons each have been delivered, resulting in a total of 150 tons. If the hopper can hold a maximum of 18 tons, then when the tenth truck leaves, there will be between 132 and 150 tons in the material. The amount of material in the mat can be estimated as follows:
If the hopper is 0% full, then there are 150 tons in the mat: (150 - (18 * 0%)) = 150 tons
If the hopper is 50% full, then there are 141 tons in the mat (150 - (18 * 50%)) = 141 tons
If the hopper is 100% full, then there are 132 tons in the mat (150 - (18 * 100%)) = 132 tons
Some customers prefer to dump the truck as quickly as possible and depart the paver with the hopper nearly overflowing (100% or 90% full). Others prefer to have the truck leave when the hopper is almost empty (25%, 20%, or 10% full), with the next truck ready to replace it when the hopper is almost empty. Still, others prefer a compromise (50%). Due to the hopper's large capacity, it is necessary to estimate the amount of material in the hopper when the truck departs to estimate the total amount of material in the mat and the amount remaining in the hopper.
When it comes to the Material-to-Finish stage, all the material for the job is in one of four places: 1) in the mat, 2) in the hopper (or possibly in a shuttle buggy/MTV, which is not yet supported), 3) loaded in trucks but not yet in the hopper (either waiting at the job or en route from the plant to the job), or 4) not yet loaded. MPC is working to determine where every pound of asphalt is in relation to these four locations. Then, in conjunction with the distance paved (as measured by a FleetWatcher black-box), both the yield and material to finish can be calculated in real-time, making it a DYNAMIC system.
Definitions:
Mat: This term is used to describe new asphalt surface positioned behind the paving machine. It refers to asphalt during the laydown and compaction processes.
Yield: How much Mat is laid to cover the road/ground surface. A given length and width of road can be paved with (X tons) of asphalt based on how thick the asphalt is laid.
Mainline Paving: Mainline paving jobs (shifts) are those where paving runs in one direction on a freeway or road with no abrupt changes in direction. In contrast to this are jobs like neighborhoods, city streets, and parking lots where paving is discontinuous and often for only short distances between turns and/or breaks. Mainline paving is also typically characterized by consistent widths for many miles and often for many days of paving.
Depth: Depth is the thickness or height of the mat laid after compaction.
Weight/Density: Density is a reference to a material’s weight at a certain volume. A certain asphalt density is attained with mechanical compaction of the hot material after paving equipment places it.