1 MARCH 2000
WCar = 187 tons
NCar = 25
G = 60,000 / 20(170 + 25 x 187) - 0.15
Grade length = 26 (engine and cars) x 70 = 1820 Feet (or longer)
Thus, grades of 1820 feet or longer would have to be limited to an effective gradient of 0.47%.From a
brief review of contour maps of the area through which the route would run, the designer believes the
route may require grades much steeper than 0.47% to keep construction costs at an acceptable level.
One way to accommodate the desire to move single trains of 25 loaded flats at a minimum speed of 15
MPH and allow for a steeper ruling grade is to use the installation's engine and commercial engine
together and drop the travel speed up the ruling grade to 10 mph, which should further increase the
tractive effort available. To offset the loss in speed up the ruling grade, other portions of the route might
be constructed to accommodate higher speeds - perhaps 25 to 30 mph. A check of this possibility shows
For the commercial locomotive:
Traction at the Adhesion Limit = 340,000 / 4 = 85,000 lbs.
Locomotive Tractive Effort at 10 MPH = 300 x 3,000 / 10 = 90,000 lbs.
Wheel-rail adhesion governs usable tractive effort.
For the installation's locomotive:
Traction at the Adhesion Limit = 200,000 / 4 = 50,000 lbs.
Locomotive Tractive Effort at 10 MPH = 300 x 1,500 / 10 = 45,000 lbs.
Engine power governs usable tractive effort.
3. Ruling Grade (from Equation 3-3):