2018 Sacramento Overlay Project
The City of Sacramento contracted with CAInc to provide professional engineering services to perform traffic counts and preliminary pavement coring on the five roadway segments within the city. The traffic counts will be used to determine existing traffic indexes and the pavement cores will be used as a basis for overlay/rehabilitation design which will be completed in the final design phase. Project boundaries for each road consist of:
- Folsom Blvd – From Power Inn to Florin Perkins Road
- Mack Road – Morrison Creek Bridge to Stockton Road
- J Street – From 16th Street to 30th Street
- Natomas Boulevard – North Park Drive to Elkhorn Boulevard
- Grand Avenue – Rio Linda Boulevard to Marysville Boulevard
CAInc is preparing Pavement Design Memorandums for the five projects, which includes coring the pavement to measure existing asphalt concrete and aggregate base, evaluating the condition of the existing pavement, and providing rehabilitation recommendations and overlay options for each road. Recommendations include: Full Depth Reclamation (FDR), Deep Lift HMA Replacement, New Pavement Sections, Reduced Traffic Index Option, and Full Depth Reclamation/Cold In-Place Recycling (CIP).
Mosquito Road Bridge at South Fork American River
El Dorado County, California
This currently in-process project will replace the existing single-span, steel suspension bridge (originally constructed in the 1800’s, replaced in 1939, and rebuilt in 1985 and 1990) and eliminate the steep roadway approaches to provide all weather access and decrease transit times between the communities of Placerville and Mosquito. The proposed bridge is an 1180-foot long balanced cantilever structure consisting of three spans (322 ft – 536 ft – 322 ft) of cast-in-place/pre-stressed concrete segmental box girder construction. The bridge deck will be about 495 ft above the South Fork American River and descend about 40 ft from southeast to northwest. The abutment foundations will be established about 10 to 20 ft below existing ground surface. The pier foundations will be established in the steep canyon slopes about 160-170 ft above the river requiring cuts on order of 50-60 ft high. Retaining walls are also planned at Abutment 1 to retain approach fill. Geotechnical services included permitting, geologic review/reconnaissance, geophysical surveys, twelve test borings, soil and rock core sampling, laboratory testing, petrographic examination of rock cores, drafting and preliminary geotechnical evaluation/analysis. The field exploration program required clearing the proposed pier locations, constructing temporary platforms and use of a helicopter to transport the drill rig to pre-selected boring locations.
CAInc prepared/submitted a Preliminary Foundation Report for the for the type selection phase of the project. This report summarizes subsurface foundation conditions and provides laboratory test results, seismic data, preliminary LPile parameters, the Log of Test Borings preliminary foundation information/recommendations and construction considerations. Tentatively, large diameter cast-in-drilled-hole (CIDH) piles socketed into rock are considered appropriate at Abutment 1, Pier 2 and Pier 3. Shallow spread footing foundations founded in the underlying rock are considered appropriate at Abutment 4, likely with some slope “augmentation” such as rock anchors/bolts. CAInc will prepare a Foundation Report following bridge type selection that will provide final foundation recommendations based on defined foundation type and load data.
Washington/Andora Bridge Widening Project
Roseville, Placer County, California
The project involves widening Washington Boulevard from Sawtell Road (south) to Pleasant Grove Boulevard (north) and the replacement of the Union Pacific Railroad (UPRR) Andora Underpass bridge structure. Based on conversations with Mark Thomas & Company, the UPRR bridge replacement is expected to consist of a longer and wider multi-span structure with either two or four spans. A shoo-fly is planned to allow staged construction of the railroad bridge. For the new railroad bridge, Crawford & Associates, Inc. (CAInc) prepared a Preliminary Foundation Memorandum for the preliminary engineering phase and will prepare a Foundation Report for the final design phase. Design of the railroad bridge is expected to be in accordance with the American Railway Engineering and Maintenance-of-Way Association (AREMA) Manual for Railway Engineering. CAInc will prepare the reports consistent with current Caltrans format.
For the roadway widening project elements, CAInc prepared a Geotechnical Design/Materials Report. Roadway improvements consist of two northbound and southbound lanes, curbs; gutter; sidewalk; curb ramps; Class II bike lanes; striped center median; and drainage system improvements. Recommendations were provided for cuts and excavation, embankment fills, Type-1 concrete retaining wall, and new culvert size and types. CAInc completed R-value tests (CTM 301) on bulk samples of native soils to determine pavement sections for new roadway pavement. Key Geotechnical Elements
- New/modified cut/fill sections, new pavement sections
- Retaining walls; new/modified drainage facilities
- Depth to competent/firm bearing material for new bridge, retaining wall, and culvert foundation support
- Potential for shallow groundwater due to surface water in nearby creeks for foundation excavation considerations
- Soil corrosivity for drainage/foundation elements
- Potential presence of coarse materials (cobbles/boulders) or other debris within existing railroad embankment for excavation/shoring considerations.
- Protection of underground and overhead utilities
- Protection of the railroad tracks and facilities
- Shoo-fly track for staged construction and possible environmental (hazardous materials) issues along railroad right-of-way (spills, utilities, etc.)