Category: Monthly Webinar Caltrans’ 21st Avenue Bridge: Identify & Implement

September 15, 2022 1:00 pm

David Carlin, P.E., Structure Representative, Structure Construction Unit 3665, California Department of Transportation (Caltrans); and Q&A panel members Brandon Miller, P.E., Bridge Construction Engineer, Unit 3665-7, Caltrans; Hogni Setberg, P.E., Bridge Construction Engineer, Unit 3665-5, Caltrans; and Kuruswamy “Selvan” Selventhiran, P.E., Senior Bridge Engineer/Specialist, Office of Bridge Design – ABC Branch, Caltrans

Webinar Documents:
Caltrans’ 21st Avenue Bridge: Identify & Implement - pdf of presentation
Q&A Session - pdf
News - September 15, 2022 - pdf of presentation

Description: The 21st Avenue Undercrossing on SR 99 in Sacramento was identified in need of critical repair through the Department's Maintenance and Investigations program after a decades-long assessment and repair program. With full replacement of the superstructure identified as necessary, the project development team began the process of evaluating alternate delivery and construction methods considering the 220,000 ADT, proximity to existing homes, and the safety implications of construction adjacent to live traffic lanes. Multiple design alternatives were considered with extensive input from others, leading to the selection of readily-producible precast prestressed concrete box girders with UHPC connections for the 51-ft-long, 140-ft-wide single-span bridge. This presentation focuses on how the project team worked to incorporate lessons learned on the 2020 Echo Summit Sidehill Viaduct Replacement Project to refine both the contract structure as well as pre-construction approach. The selected Contractor entered the construction phase with a comprehensive plan, and the project was delivered in 2021 with a 96-hour closure and as little impact to the traveling public as possible.



David Carlin, P.E.
Structure Representative
Structure Construction Unit 3665
California Department of Transportation

David, operating out of Caltrans’ Shingle Springs office in District 3, brought over 16 years of structures-related experience with him when he joined the Department in 2020. His career began in Southern California where he operated as a consultant for Caltrans, North County Transit Agency, the San Diego Association of Governments, and a variety of municipal clients. As such, David affords his projects a variety of both contract and project management strategies which have proven very effective in the execution of two of Caltrans’ most recent ABC successes, the 21st Ave UC and Echo Sidehill Viaduct Replacement Projects.

Presentation Photos/Graphics:

1)  Continuous public outreach allowed the project team to mitigate impacts as well as facilitate planning and a sense of curiosity amongst the impacted community members

2) Test-fitting of the girders, a contract requirement directly resulting from experience on the Echo Summit Sidehill Viaduct Project, allowed for cumulative casting tolerances to be accounted for and quantified… no surprises on site

3) Real time monitoring of progress relative to intermediate demolition milestones allowed the Contractor to anticipate and plan for strategic opportunities for acceleration and concurrent work

4) A comprehensive UHPC placement plan, including modified monitoring requirements and a full test run, also benefited from recent experience with this relatively new product and application

5) Elevation view westerly along 21st Avenue showing the completed superstructure replacement, soundwall, and tie-ins to the adjoining walls

6) The completed precast girder assembly, as well as supplemental corbel incorporated during construction to supplement the existing strutted abutments