G = The maximum allowable compensated grade in %,
D = Degree of curve,
c = 0.04, compensation factor in % grade per degree of curve,
r = The maximum grade achievable by the train in %.
The above relation is a design tool to combine grade and curvature. The author intends to modify the above relation for two purposes —
• to make the relation more rational for combining grade and curve for LRT design, and
• to make the relation useful in computing the installation slope of special trackwork.
c = compensation factor in % grade per degree of curve determined on the basis of curvature,
k = grade reduction factor arbitrarily chosen between 0.2 ∼ 1 depending on curvature and type of rail.
The justification of the proposed modification and the advantages of the modified formula are discussed in details.