As discussed in the CMP Introduction, the level of system performance that is acceptable to a motorist varies based on the type of transportation facility he or she is using.  For instance, the level of congestion that a traveler is willing to accept on an Interstate highway is not the same as what that traveler is willing to accept on a downtown street.  Therefore, when comparing the performance of transportation facilities, it is beneficial to differentiate between types of facilities in order to “compare apples-to-apples”.

The 2000 Highway Capacity Manual (HCM) defines four categories of urban streets based on the characteristics of the roadways and their surrounding areas.  The criteria for determining these classifications are illustrated below in Exhibits 10-3 and 10-4 from the HCM.

Based on this classification system, SPC has compiled regional ratings for each of the following types of roadways on the CMP network:

• Interstate Corridors;
• Class I Arterial Corridors;
• Class II Arterial Corridors;
• Class III Arterial Corridors; and,
• Class IV Downtown Corridors.

Regional ratings for the following performance measures are provided for each of the corridor classifications:

• AM Delay / Vehicle / Mile (minutes per mile);
• PM Delay / Vehicle / Mile (minutes per mile);
• AM Total Delay (vehicle-hours);
• Total Peak Hour Delay (vehicle-hours);
• AM Total Delay / Mile (vehicle-hours per mile);
• PM Total Delay / Mile (vehicle-hours per mile); and,
• Total Peak Hour Delay / Mile (vehicle-hours per mile).

Definition, explanation, and discussion of these performance measures can be found in the CMP Glossary and in the Performance Measures section of this website.

These ratings will be updated semiannually as additional data is collected throughout the SPC region.

CMP Corridor Maps:

Pick A Map:

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For more information about our Congestion Management program, contact Doug Smith at (412) 391-5590 x327 or e-mail dsmith@spcregion.org.

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