1 MARCH 2000
L ≈a +C + d
L = Lead (feet).
a = Switch length (feet).
C = Long chord (feet).
d = Frog toe length, from AREMA Plan 910, Column 19 (feet).
l. Equilateral Turnouts. In an equilateral turnout, the diverging angle (frog angle) is divided equally on
both sides, thus the turnout has two curved stock rails and two curved closure rails that mirror each other.
Likewise, the degree of curve along each closure rail is half that of a standard left or right-hand turnout.
m. Turnouts on the Inside of a Curve.
(1) When not required by space limitations or other local conditions, turnouts to the inside of a curve
will be avoided.
(2) Curvature through a turnout on the inside of a curve equals the degree of curvature for the curve
plus that for a standard turnout. Thus, a number 10 turnout off the inside of a 3 degree curve will have a
curvature of 3 + 7.4 = 10.4 degrees. The total curvature must not exceed design limits.
18. TRACK CONNECTIONS AND LADDER TRACKS.
a. Diverging Routes.
(1) Figure 6-29 shows the layout for a typical diverging route connection. Note that the angle that the
route diverges is the same as the frog angle for the turnout. The distance from the intersection of track
center lines to the location of the frog point is given by equation 6-16.