Figure 6-13. Design Wheel Configurations

CEMP-E

TI 850-02

AFMAN 32-1125(I)

1 MARCH 2000

(3) The track is evaluated assuming that a wheel is centered over a tie, with an adjacent wheel on

either side contributing to the loads, deflections, and stresses  as occurs when two cars are coupled

together. Referring to figure 6-13(a), the maximum tie, ballast, and subgrade loads will occur under

wheels one and four (counting from the left), while the maximum rail bending stress will occur at wheels

two and three. For the wheel configuration in figure 6-13(b), the maximum tie, ballast, and subgrade

loads will occur under wheels two and five, while the maximum rail bending stress will occur at wheels

three and four.

(4) The effect of wheels farther than 100 in. from the design wheel is negligible.

d. Select Trial Track Modulus (u). The track modulus values listed in table 6-6 are suggested starting

points for design. In the table, track type "main" refers to main running tracks, while "auxiliary" includes

sidings, wyes, loading, spur, storage, interchange, and light use tracks.

Table 6-6. Suggested Design Track Modulus Values

Design Wheel Load Range (1,000's of pounds)

Track Type

20 - 25

25 - 30

30 - 35

35 - 40

40 - 45

45 - 50

Main

1500

1800

2000

2300

2600

2900

Auxiliary

1200

1300

1500

1700

2000

2200

6-16