# Calculation Parameters and Formulas

## General parameter

Figure 1 show the general parameters of platform edge design. All parameters are the offset distance that reference from designed centreline of platform edge.

Figure 1

Figure 2

The distance from the reference track (positioned by default in the middle of the rails) is calculated using the following formulas:

Ai = Ao + Kir = Ao + iR

Ay = Ao + Kiy = Ao + yR

## Platform edge formulas in different case

### Track without Cant

On a straight section

In curve section

In the case of straight and curve sections without cant the height of platform is constant with Hp. Calculation of the horizontal increments for platforms at the inner or outer side is based on the following parameters and formulas:

The horizontal increments, Kir and Kyr, are defined by a theoretically carriage with length 24.0m, and axle base 18.0m. The curve increments for curves with R >180.0m can then be calculated with the following formulas:

Track sections with transitions

In case of transition sections, the horizontal offset will increase/decrease on this section depending on the length of transition curve. The formula of platform edge is:

## Track with Cant

In the case of curve or transition section the height of platform is varying with Hi/Hy. The formulas of horizontal offset of inner and outer side and Hi/Hy of platform are:

## Transition of platform edge in different situations

In the case of line - curve combination

For line - curve combination the transition of both outer side and inner side of curve element show in the following figure:

In the case of line - spiral - curve combination

For line - spiral - curve combination the transition of both end of curve element show in the following figure:

In the case of a switch in the platform area

When a switch is specified near the new platform the horizontal edge distance calculations will be based at the switch stock rail, SS. Extra widening (Yr) will be added based on the switch radius. In the curve section the extra widening is described for every 0.5m. From SS the platform edge is described with constant widened distance the first 5.0m after SS, and then linear to normal distance 20.0m after SS.