Class-8 Heavy Truck Duty Cycle Project Final Report - Center for ...

the course of the year-long data collection period as any of the other five trucks. Besides this general
case, particular conditions such as the effect that vehicle weight and congestion levels have on the
fuel efficiency of the Class-8 trucks equipped with different type of tires are also investigated in this
section.
6.3.1
General Statistics
Over
the 12-month data collection period, the six participating trucks logged close to 700,000 miles
and consumed over 100,000 gallons of fuel while undertaking 1,100 trips15 and visiting 37 states in
the U.S. and one Canadian province. Table 14 below presents a summary of these statistics for each
one of the six participating tractors. The header of the table includes information about the type of
transmission and tires that each one of these six tractors had. The table also includes information
regarding fuel efficiencies for the entire data collection period, for each of the six vehicles as well as
their overall fuel efficiency. These calculations were made using fuel consumption information
obtained from the vehicles’ databus (last row in Table 14) and include both the fuel consumed while
the vehicle is moving as well as the fuel spent while idling. Notice that, in general, tractors equipped
with the NGSWBTs had higher fuel efficiencies than those equipped with regular dual tires.
Table 14. General Statistics for the Instrumented Tractors
Statistics
T1
1 A
(M -S )
T2
1 B
(M -D )
T3
2 A
(A - S )
T4
1 B
(M - D )
T5
2 A
(A - S )
T6
2 B
(A - D )
Grand
Total
Distance Traveled [miles] 106,891 114,095 117,355 124,917 127,626 97,417 688,302
Total Time for Which Data
3
was Collected [hrs]
3,783 4,451 3,779 4,413 4,281 3,067 23,774
Avg. Speed 4 [mph] 28.26 25.63 31.05 28.31 29.81 31.76 28.95
Total Fuel Consumed [gal] 15,982 16,701 16,805 19,361 18,494 15,995 103,336
Overall Fuel Efficiency [mpg]
From the Databus Sensor
6.69 6.83 6.98 6.45 6.90 6.09 6.66
1
atic Tran ion; 3 Includes Idling times; 3 Manual Transmission; 4Distance Traveled/Total Time for Which Data
2 Autom smiss
Was Collected (includes idling times); A NGSWBTs; B Dual Tires
The
information collected was further divided into short-haul (less than 100 miles) and long-haul
(over 100 miles) trips, and the total, moving, stopped, and idling times were calculated as well as the
fuel consumed, for all of the participating trucks combined. That information is presented in Table 15
and Table 16. The “Stop Time” and “Stop Fuel” statistics include the condition in which the vehicle
was static (i.e., not moving) and the engine was either running or not; while the “Idling Time” and
“Idling Fuel” statistics include only the condition of a static vehicle with the engine running (this
includes times when the truck was stopped because of congestion or other type of traffic related
delays).
While
short-haul trips presented proportionally larger idling times than those shown by long-haul
trips (i.e., 69.0% of the total time spent on the trip vs. 49.5% of the total time, respectively, or close
to
a 3-to2 ratio), the former consumed a significantly larger proportion of the total fuel for idling
purposes than the latter (i.e., a ratio of about 3-to-1, or 21.2% vs. 6.7%, respectively). Notice also
that short-haul trips are a very small portion (about 2.0%) of the total trips.
15 A trip is considered here as a journey in which either the origin or destination is the parking lot of the participating trucking company,
with the other end of the journey being any place other than the parking lot of the company. For example, going from Jefferson City, TN
(i.e., the place where Schrader is located) to Cincinnati, OH and coming back to Jefferson City, TN would be considered as two trips.
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