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TRANSPORTATION T/9/84 APPENDIX E INTERCHANGE CRITERIA AND PROCEDURE b. To compensate for lack of an adequate The following criteria for highway interchange complementary minor arterial or collector system; location spacing and design and the procedure C. To compensate for deficient minor arterial for processing highway interchange requests have or frontage road capacity; or been established to meet the objectives of d• To correct collector or minor arterial Transportation Policy 15. capacity deficiencies caused b or excessive access to adjacent parcels.'. poor -design INTERCHANGE CRITERIA 7. The new interchange or related system change General Transportation Criteria must be acceptable in terms of route design as specified by Mn/DOT or the implementing 1. Additional interchange capacity should be con- agency, conforming to such factors as basic sidered only when it supports regional and number of lanes, lane continuity, lane balance, local comprehensive plans as defined in the lane drops, continuity of mainline levels of Land Planning Act. service and other general design criteria. 2. When an interchange and a related system change or ramp modification is to be con- Ramp Configuration Criteria structed, the operational integrity of the mainlines must be maintained. Operational 1• Insofar as possible, standard ramp and inter - integrity is defined by the forecasted level of change configurations should be used for service and safety considerations for the main design.'Ramp features to be avoided include: through roadways. The level of service can be altered if that change is consistent with the a• Hook ramps that provide inadequate plan for the entire route. storage and deceleration distance; 3. The effect of an additional interchange or ram b' Elongated tight curvature ramps; C. Designs that create problems such as com- is considered adverse if the operating character- pound weaving on the mainlines (as defined istics of an associated weaving section are in the Highway Capacity Manual published unsafe or not consistent with those of the by the American Association of State mainline approaching lanes. A quality of flaw Highway and Transportation Officials in compatible with the mainline level of service 1965). must be maintained. 2. Interchange ramp configuration and design 4. The need for additional capacity or safety must should be based on traffic forecasts developed be demonstrated and documented before new and adopted by the Metropolitan Council and ramps are considered. Mn/DOT. 5. Interchanges must connect to a minor, inter- 3. Common interchange designs that provide land mediate or principal arterial or an a access should be used if adequate capacity can collector as defined in the functional e lapsilfica- be provided. A diamond or a split diamond is Lion system adopted by the Transportation Preferable to folded diamond, Advisory Board and a "pargns' u approved by the tailored ramp designs. Unusual designs must be Metropolitan Council. justified by special capacity or physical 6. New ramps are not to be provided if the need obstruction problems. for additional capacity is justified only: 4. Traffic backups resulting from interchange ramp designs must occur on cross streets and a• Ar; a convenience for short trips; frontage roads rather than on the mainlines.