Interchange Design Process

The Twin Peaks Interchange design is following the Arizona Department of Transportation's (ADOT) standard design process. This process includes progress submittals of plans and details and can be summarized as follows:

• Stage I Plans (15% Complete). Plans primarily consist of preliminary: Typical Section (roadway widths, number of lanes, slopes, etc.); Roadway Horizontal and Vertical controls (Plans showing the roadway line and grade), Drainage concept and other very basic elements. This submittal was made to the various review agencies (Town of Marana, ADOT, Pima County, etc.) on May 19, 2006.
• Stage II Plans (30% Complete). These plans build upon the previous submittal and include additional details and plans including preliminary: Removal Plans (showing what needs to be removed to build the new project); Bridge Plans (depicting structure type, size, location), Drainage plans (showing ditches, box culverts, storm drains), Construction Sequencing Plans (provides a concept for building the project is a logical order of operations), Traffic Signal Plans (showing pole locations, traffic controller locations). Also included at this stage are various reports relating to Drainage, Bridge Type Selection, River Hydraulics and Scour. This submittal was made to the various review agencies (Town of Marana, ADOT, Pima County, etc.) on September 29, 2006.
• Stage III Plans (60% Complete). These plans will add details to the previous submittal and will add significant detail. New plans introduced at this stage include: Retaining Wall Plans; Bridge Structure Details (superstructure plans with details for reinforced concrete features like abutments, piers, bridge decks); Traffic Control Plans (plans that support the construction sequence and guide the traveling public through the work zone); Signing and Striping Plans, Utility Relocation Plans. This stage also includes reports prepared by the Geotechnical Engineer with recommendations for structure foundations and pavement thicknesses. This submittal took place on March 2, 2007.
• Stage IV Plans (95% Complete). These plans contain all of the completed details required for a Contractor to prepare a bid and construct the project. This will include all necessary specifications that will be the basis for acceptance of the work. The purpose of this review is one final check of the plan set before the project is advertised for bidders. This submittal took place on September 28, 2007.
• Stage V Plans (100% Complete). These plans are prepared for reproduction and are a repeat of the Stage IV plans with all comments addressed from the previous submittal. At this point, the plans are ready. There are however three clearances that are required to advertise the project for the bidders: 1) Utility Clearance — This certifies that all of the utility adjustments are already made or will be made during the construction stage. It also certifies that the Railroad Construction & Maintenance Agreement is complete. The Arizona Corporation Commission must approve this agreement. 2) Environmental Clearance — The project will be checked to make sure that all commitments for environmental mitigation measures identified in the Environmental Assessment are implemented or specified. It will also certify that all of the required permits from regulatory agencies are in place, and 3) Right of Way Clearance — The Contractor must be authorized to work within property owned by the State or Town of Marana. The Stage V submittal will take place in February, 2008. The Bid Advertisement Date is not set at this time, however this is anticipated in summer 2008.