Create events

Events are created by registering business tables with the advanced linear referencing system (ALRS) on the ALRS Properties dialog box. Event layers are either local, meaning they reside within the geodatabase that houses your ALRS, or external, which means they reside outside of the geodatabase. External events can be stored in another geodatabase, an Access database, a dBASE file (.dbf), an Excel spreadsheet, or an Object Linking and Embedding Database (OLE DB) connection.

As a database administrator (DBA), you have the ability to change primary keys on event tables without impacting the ALRS. This gives you the opportunity to change event tables without reregistering events.


It is highly recommended that you create an index on the following columns to improve performance in your event tables:

  • Event ID
  • RouteID
  • Measure
  • FromDate
  • ToDate

Events versus reference offset events

Esri Roads and Highways splits event registration into two main branches: events and reference offset events. When registering events, you specify a route and measure combination to mark the location of an event on a network. When registering reference offset events, you locate events based on an offset from the location of another entity. In some cases, that entity could be another event, point feature class, or X and Y coordinates.

There are four different types of events that can be created:

Reference offset events versus perpendicular offsets of events

Reference offset events should not be confused with perpendicular offsets of events. Reference offset events are offsets along the route. Perpendicular offsets are applied to a route and offset at a right angle off of the route. For more information, see Setting perpendicular offsets for event layers.