Special Explication

Definition

Special Explication indicates a point where a road splits into two or more roads. If no route guidance advice was provided, the driver may not be able to determine in which direction to continue.

Usage

The Special Explication relationship can be used for map display and route guidance.

Specification

At qualifying decision points (see rules below), two or more Special Explication conditions are always added, one for each road segment after the split. The following image shows a case where Special Explication is required.

• The Access Characteristics of the Special Explication condition is flagged for all Vehicle Types.

• A Special Explication condition is applied when:

  • The driver perceives a non-Controlled Access road as splitting and instruction to keep to the left or right is necessary to continue in the correct direction.
  • The driver perceives a controlled access road as splitting into two or more controlled access roads.
  • The driver perceives a Highway-to-Highway Connector as splitting into two or more Highway-to-Highway Connectors.
  • The controlled access road widens to include two (or more) extra lanes for at least 1000 metres before the decision point. In this case, the driver perceives a motorway as splitting into a motorway and a Highway-to-Highway Connector.

• A Special Explication condition is not applied in situations where an instruction to keep to the left or right is not necessary. The following are examples:

  • Splits of low speed ramps
  • Highway splits on approaches to toll structures to accommodate different toll paying options
  • Motorway with exit ramp