The difference between rigid pavement performance in downtown Sunnyvale versus the residential areas near the Sunnyvale Baylands is striking. In the Baylands, soft estuarine clays compress under heavy loads, demanding thicker slabs and doweled joints. Downtown, where older alluvial sands dominate, we can often reduce slab thickness by 2 to 3 inches. That is why we always start with a site-specific soil investigation before committing to a rigid pavement design in Sunnyvale. A proper subgrade assessment, including CBR and resilient modulus testing, prevents costly overdesign or premature cracking. We typically pair this with a CBR vial evaluation to confirm the subgrade support values under soaked conditions. The result is a pavement that lasts 25+ years without major rehabilitation.
A slab on soft clay without proper subgrade treatment will crack in under two years. We prevent that.
Method and coverage
We recently designed a rigid pavement for a logistics center near the Sunnyvale Municipal Airport. The soil profile there — 8 feet of stiff clay over dense sand — required careful joint spacing and load transfer analysis. For heavy truck traffic, we used 28-day flexural strength of 650 psi and tied contraction joints every 15 feet. To validate the subgrade modulus, we performed plate load tests and correlated results with ensayo Proctor compaction control. Our team follows the AASHTO 1993 Guide with the 1998 supplement for mechanistic-empirical design. We also integrate Caltrans Highway Design Manual criteria for state-funded projects. Key steps we take:
Technical reference image — Sunnyvale
Regional considerations
Sunnyvale sits at an elevation of 130 feet above sea level, but groundwater can be as shallow as 4 feet in the low-lying areas near the Bay. High water tables reduce subgrade support and cause pumping of fine material under joints. Additionally, the region's seismic hazard — peak ground acceleration of 0.6 g per USGS — means rigid pavement must withstand lateral spreading and differential settlement. Ignoring these factors leads to faulted joints, slab corner breaks, and premature failure. Our rigid pavement design incorporates drainage layers, tied concrete shoulders, and seismic joint reinforcement to mitigate these risks.
We drill borings, collect undisturbed samples, and run lab tests (CBR, resilient modulus, Atterberg limits) to characterize the subgrade. Our reports include a recommended design modulus for Sunnyvale soils.
02
Structural Pavement Design
We compute slab thickness, joint spacing, dowel bar sizing, and reinforcement steel. Output includes plan sheets, joint layout, and construction specifications tailored to local aggregate availability.
03
Seismic & Drainage Analysis
We evaluate liquefaction potential under the pavement, design subgrade drainage systems, and specify tied shoulders to resist lateral loads. Deliverables include a drainage report and seismic hazard memo.
Standards that apply
AASHTO 1993 Guide for Design of Pavement Structures (1998 supplement), Caltrans Highway Design Manual (Chapter 630), ASTM D1883 (CBR), AASHTO T97 (flexural strength), ACI 325.14R (joint spacing for concrete pavements), ASCE 7-22 (seismic load criteria for pavements)
Frequently asked questions
What is the typical slab thickness for rigid pavement in Sunnyvale?
For residential streets with light traffic, we typically design 6-inch slabs. For industrial or truck routes, thickness ranges from 8 to 12 inches depending on subgrade CBR and traffic volume. Our designs always meet Caltrans standards.
How does high groundwater affect rigid pavement design?
Shallow groundwater reduces the effective subgrade modulus and can cause pumping of fines under joints. We mitigate this by specifying a 6-inch granular drainage layer, edge drains, and a 4-inch separation geotextile to prevent subgrade erosion.
Do you account for seismic loading in pavement design?
Yes. For Sunnyvale, we evaluate liquefaction potential using CPT or SPT data and apply ASCE 7-22 site class factors. We then design joints with seismic ties and specify dowels that allow horizontal movement without losing load transfer.
What is the cost range for a rigid pavement design study?
A full design study including soil investigation, lab testing, and structural design typically ranges between US$1,920 and US$6,770. The final cost depends on project size, number of borings, and required testing scope.
