1 MARCH 2000
5. LOCOMOTIVE TRACTIVE EFFORT.
a. Definition. When designing a railroad route, it is necessary to know how much pulling force a
locomotive is capable of exerting. This pulling force is known as tractive effort. Tractive effort is
maximum at starting and diminishes as speed increases.
b. Application. Locomotive tractive effort, along with the route gradient and curvature, will largely
determine how many cars can be pulled over the route in a single train. From another perspective,
locomotive tractive effort and minimum desired train size may determine the maximum grade and
curvature tolerable on a given route.
c. Tractive Effort Data. Tractive effort data (or graphs) are often available for both military and
commercial locomotives. When not readily obtainable, the data can be estimated from the locomotive
weight and engine horsepower rating. This procedure is covered in chapter 3, paragraph 5.
6. TRAFFIC AND TERMINALS. Once the traffic handling requirements have been identified, as
described in chapter 2, paragraphs 1 to 3, the process of designing the terminal and support facilities can
begin. The number and size (or length) of the required facilities and serving trackage is based on these
traffic requirements. Chapter 8 covers planning and design for terminals.
7. SOURCES FOR TRAFFIC INFORMATION. Information about traffic types, car types, and volume,
and mobilization requirements should be obtained from the Installation Transportation Officer (ITO) and
from the installation Transportation System Capability Study prepared by the Transportation Engineering
Agency of the Military Traffic Management Command (MTTE-SEF).