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MDT - Filtering a Route by Reference Post and Offset
MDT - Filtering a Route by Reference Post and Offset
Greg Olsen avatar
Written by Greg Olsen
Updated over a week ago

When selecting a route in AASHTOWare Safety, it is recommended to use a combination of two filters: Corridor Name, and Reference Post and Offset (Integer).

Corridor Name

The Corridor Name is the 7-character code used to identify the route. Each corridor name begins with the letter C, and is followed by six digits.

For example, Interstate 90 has the Corridor Name of C000090.

Note: When using the Corridor Name filter, a nested MP filter will appear after the selected corridor name. Do not use this filter to define the Mile Post of the selected corridor, as it does not also include the offset and will return inaccurate results.

Reference Post and Offset

The Reference Post and Offset is made up of two parts: the reference post, a one, to three-digit value; and the offset, a four-digit value. Outside of AASHTOWare Safety, this is displayed as a single value, joined with a plus sign (See examples below).

227+0.295, 83+0.001, 1+0.083

Inside of AASHTOWare Safety, this can be added as a filter using the Reference Post and Offset (Integer) filter. In order for this filter to function, some reformatting has taken place. The plus sign and the decimal from the Offset have been removed. The combined reference post and offset value is then displayed as a single, seven-digit value (the first three digits representing the reference post, and the last four digits representing the offset, with the decimal removed).

The table below shows how each of the example reference posts and offsets displayed above would be entered into AASHTOWare Safety.

MDT Reference Post and Offset

AASHTOWare Safety Reference Post and Offset (Integer) Filter Value







Additionally, you can change the operator in the Reference Post and Offset filter from the equals sign, =, to the Is Between operator, ≤/≥. This will allow you to set a range of reference post and offset values, rather than just a single value.

In the example below, we have used these filters in Crash Query to find all crashes that occurred on Interstate 90, between the following reference posts and offsets: 226+0205, and 227+0.295.

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