Interchange diagrams are created in Program Development and are the official UDOT source for all ramp numbering.

Ramp Identifier Number

Five data fields have been defined and make up the standardized ramp identifiers. The ramp identifier is made up of the state route, direction of travel, roadway type, interchange number and ramp number. 

The five fields are:

ROUTE - XXXX
DIRECTION - D
ROADWAY TYPE - T
INTERCHANGE NUMBER - YYY
RAMP NUMBER - ZZ

If the five fields are concatenated into a single identifier, the 11 characters result would be represented as follows:

XXXXDTYYYZZ

Where:

YYYYMMDD - identifies the date the route is being referenced
XXXX - identifies the route or zone number,
D - identifies the direction (positive, negative, or null),
T - identifies the roadway or type or zone,
YYY - identifies the interchange number, if required,
ZZ - identifies the ramp number or C-D roadway associated with the interchange.

The data elements making up the roadway identifier are required as needed from left to right.

Roadway Type (T)

Roadway Type will be a 1-digit character-type field indicating the type of roadway or zone designation. 

Choices are:

M - mainline roadway and interchanges (default value)
R - a ramp, either on or off
C - a collector-distributor roadway
T - traffic circle (roundabout)
Z - local road zone
X - Misc.