Highway Hauling

The quickest way to communicate the key issues in highway hauling is with a simple analysis. The cost factors used in this example are representative, but they will be different in different local economies.

Truck cost is well defined by a mature trucking industry. Ownership cost plus operating cost (routine maintenance, driver labor cost, insurance, license, taxes, fuel) are known for short-haul operations. A truck can be used to haul gravel, logs, or hay bales and the short — haul cost ($/d) is approximately the same. The way to minimize truck cost ($/ton) is to maximize truck productivity (tons hauled per day, per week, or per year). Two issues are significant:

1. Tons per load.

2. Truck cycle time — time required to load, haul, unload, and return for the next load.

Hauling cost is defined here as loading cost plus truck cost plus unloading cost. The reader can quickly grasp the interaction of these three operations by considering the following example.

13.6.1 Truck Cost

Suppose it takes 40 minutes to load a truck and this truck travels 25 miles at an average speed of 45 mile/h. (This is a reasonable average speed for short hauls over rural roads.). It takes 40 min to unload the truck (no waiting in a queue) and then it returns 25 miles at 45 mile/h. The cycle time is 146 min = 2.4 h. In a 10-h workday, this truck can haul four loads.

Suppose the cost for the truck (ownership + operating) is $450/d and the cost of fuel is $3.50/gal. The truck averages 4 mile/gal, which is typical for short-haul operations. Fuel cost per load is:

(25 mile x 2)/(4 mile/gal) = 12.5 gal x $3.50/gal = $43.75/load The truck hauls four loads per day, thus the fuel bill is:

$43.75/load x 4 loads/d = $175/d

Total truck cost is:

$450/d (ownership + operating) + $175/d (fuel) = $625/d

If the load is 12 dry tons, the cost per dry ton is:

Подпись:$625/d

4 loads/d x 12 dry ton/load

Now suppose this same truck, hauling the same dry ton per load over the same distance, can be loaded in 10 min, not 40 min, and it is unloaded in 10 min, not 40 min. Now the cycle time is 86 min = 1.43 h and the truck can haul seven loads in a 10-h workday. (This comparison is an idealization — no travel delays are allowed, which is not realistic in a real-world situation. Also, the assumption that the truck never has to wait to be loaded and unloaded is unrealistic.)

The truck hauls seven loads per day, thus the fuel bill is:

$43.75/load x 7 loads/d = $306/d

Total truck cost is:

$450/d(ownership + operating) + $306/d (fuel) = $756/d The cost per dry ton is:

Подпись:$756/d

7 loads/d x 12 dry ton/load

Truck cost has been reduced from $13 to $9/dry ton, or 31%, by just loading the truck more quickly and unloading it more quickly.

Fuel cost ($306/d) is 40% of the truck cost. Fuel cost ($/dry ton) is a key parameter in the entire biomass logistics chain, not only truck cost, and it increases whenever the world market for transportation fuel produces a price increase. This linkage, more than any other single factor, limits the distance that raw biomass can be hauled, cost effectively, by truck.

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