Use the following set of variables to calculate transition distances.
| {e} | The full superelevation rate. This rate is determined from the superelevation rate table, based on the design speed and curve radius. |
| {t} | The value that is read from the transition length tables, based on the design speed and the curve radius. In most cases, such as AASHTO, this is the transition length value from Level Crown to Full Superelevation. However, this value may not be an actual length, but some other value, such as a transition rate from which the length can be calculated. |
| {c} | The unsuperelevated normal lane crossfall (positive). This value is defined by the user in the Calculate Superelevation - Lanes Page. |
| {s} | The unsuperelevated normal shoulder slope (positive). This value is defined by the user in the Calculate Superelevation - Shoulder Control Page. |
| {w} | The normal width of the carriage way. This value is defined by the user in the Calculate Superelevation - Lanes Page. |
| {l} | The length of the transition, if a transition is involved in the transition. This is the actual length of the transition element in the curve group. |
| {p} | The fractional part of the transition length before the start of the curve or after the end of the curve. |
| {q} | The rate of increase of centripetal acceleration traveling along a curve at a constant speed. |
The variables in the previous table are used to calculate the following:
| XML Code | Description | Example |
|---|---|---|
| NC | Normal Crossfall |
 |
| LC | Level Crown |
 |
| RC | Reverse Crossfall |
 |
| FS | Full Super |
 |
The following table describes the formulas:
| LCtoFS |
 |
The distance from the Level Crown Chainage to the Full Superelevation chainage is the value {t}, which is read from the selected transition length table. The formula assumes that the transition length table defines the runoff length. |
| LCtoBC | The distance from the Level Crown chainage to the Beginning of Curve chainage is a percentage of the runoff length{t} based on the variable {p}. | |
| NCtoLC |
|
The distance from Normal Crossfall chainage to the Level Crown Chainage (straight runout) is calculated as the runoff length {t}, time the normal crossfall slope {c}, divided by the full superelevation rate {e}. The straight runout length is extrapolated from the runoff length. |
| LCtoRC |
|
The distance from the Level Crown chainage to the Reverse Crossfall chainage. (typically uses the same formula as NCtoLC) |
| NStoNC | Normal Shoulder point to Normal Crossfall point. (used for Breakover Removal Method of superelevated shoulders and Match Lane Crossfalls) |