15th Avenue to Cave Creek Road | Phoenix, AZ
Structural | Transportation
Sonoran Boulevard was one of the most important east-west routes between I-17 and the fast-growing northeast Phoenix region. The project began at 15th Avenue and terminated at Cave Creek Road with a total length of approximately seven miles. Premier designed bridge structures over Apache Wash, Cave Creek Primary Wash and Cave Creek Secondary Wash. Structural design recommendations and services resulted in reduced construction costs, future construction considerations and aesthetic treatments included:
- Pre-design documents estimated the construction of 2,800 feet of bridges. Since the land located upstream of the bridges belonged to the City and was designated as the Sonoran Preserve, the City agreed to exceed the 100-year FEMA Floodplain elevation at Apache Wash which allowed a significant reduction in bridge length and construction cost at this location. Working hand-in-hand with the drainage engineers, the total length of bridges was reduced to 954 feet.
- Premier recommended the construction of precast prestressed AASHTO type V concrete girders for all three bridges. Two girder lengths were utilized throughout all bridges to reduce fabrication costs.
- The City requested construction of ramps at each bridge abutment to allow maintenance crews access to the bottom of the wash from the roadway. The proximity of the ramps to the bridge abutments would have required construction of full height abutments which would have raised the cost of construction significantly. To reduce construction cost, Premier recommended a non-standard abutment that consisted of a stub abutment on one end transitioning to a full height abutment at the end in close proximity to the access ramps; concrete round columns and a cap beam transfer the superstructure loads to the drilled shafts. A concrete fascia was attached to the columns to retain the soils behind.
- The City secured an artist to work directly with the design team to provide aesthetic treatments. A pedestrian balcony with shade structures, custom bridge railing, and mosaic tiles on the bridge parapet were constructed at all bridges.
- The bridges were designed to accommodate dry utilities which could be used by the city and utility companies in the future. Block-outs were constructed at all bridge diaphragms for future construction.