Superelevation in OpenRoads can be calculated in two ways:

Rules-based - using a set of preferences files (SRL and SEP files)
Import - using a comma separate values (CSV) file

This wiki provides information on the SRL rules files and examples of the SRL file and associated files.

The superelevation rules file incorporates national or local standards, and rules can be modified to allow for local variations from national standards. Rules consist of tables of criteria and user defined formula.

The rules are assembled in a series of external text files which are prepared outside of OpenRoads. The main files are:

.srl - the main rules parameter file.

.sel - the crossfall rules to be applied to carriageways.

.trl - the superelevation changeover lengths for transitions.

.ntl - the superelevation changeover lengths when there are no transitions.

.ckl - the transition lengths check table.

.sgl - the lengths required for special geometry.

.ssl - the lengths required for short straights.

.sal - the lengths required for early starts or steepening the application.

For any set of design rules, the .sel and .srl files must exist but the other files are optional.

If the design rules vary for different road types, each road type must have its own set of rules files, though these can be shared if the name of the file is defined in the rules parameter file (.srl).

The features of the design rules are:

• The rules adhere to national standards but can be modified if necessary.
• Equations and look-up tables are used within the rules to calculate the amount, type and length of application of superelevation to apply for a specified design speed and radius of curve.

Other factors can be taken into account if required, such as the number of lanes, lane width, channel gradient etc.

• Superelevation may be applied on all or part of a transition, and the location of the application may be specified relative to the curve.
• Superelevation may be applied when no transitions exist.
• Removal of adverse camber before the start of a transition may be incorporated.
• Superelevation may be applied across circular curves of the same or opposite hand (`C' or `S' curves) according to defined criteria.
• The parts of the alignment where superelevation is applied are checked to ensure that they do not overlap.

Examples of the main rules files can be downloaded at the link below.

SLR Rules Files

An editing guide can be downloaded at the link below.

SRL Superelevation Files Editing Guide