San Bernardino sits at an elevation of 1,050 feet on the alluvial fan of the Santa Ana River, where daily summer temperatures frequently exceed 100°F. This combination of high heat and variable subgrade moisture cycles accelerates pavement distress such as rutting and fatigue cracking. A thorough existing pavement evaluation in San Bernardino begins with Falling Weight Deflectometer (FWD) testing per ASTM D4694 to measure layer moduli, followed by dynamic cone penetrometer (DCP) checks for subgrade strength. These data feed directly into overlay thickness calculations using the AASHTO 1993 Guide. For projects near the I-10 or I-215 corridors, where truck traffic volumes are high, we complement the structural assessment with a pavement analysis for flexible design to verify that remaining life aligns with expected ESALs.
FWD deflection basins and DCP profiles together reveal the residual structural capacity of pavements aged by San Bernardino's extreme thermal cycles.
Approach and scope
A common mistake contractors make in this region is skipping the coring step and relying solely on surface crack surveys. Without full-depth cores extracted per ASTM D1586 and D2487, you miss the subbase moisture profile and the exact thickness of each layer. In San Bernardino, where expansive clays from the Cajon Pass formation can cause differential heave, this oversight leads to premature overlay failure. The evaluation procedure includes both laboratory tests like California Bearing Ratio (CBR) on soaked samples and field density testing with the sand cone method to confirm compaction near pavement edges. We also perform a stability analysis for embankments when the pavement sits on fills adjacent to drainage channels, a common condition in the city's floodplain zones.
Technical reference image — San Bernardino
Site-specific factors
Operating the FWD trailer on San Bernardino's older arterial roads — many with narrow lanes and no shoulders — requires careful traffic control. The drop weight generates a 9,000-lbf impulse that can induce vibration in adjacent utilities if the pavement is severely delaminated. Our field crew uses ground-penetrating radar (GPR) ahead of testing to identify voids or saturated zones that could cause instability under the load plate. In areas near the Santa Ana River wash, where the water table rises within 5 feet of the surface, we switch to a lightweight deflectometer to avoid exceeding the bearing capacity of the softened subgrade during the existing pavement evaluation in San Bernardino.
Non-destructive testing using a Falling Weight Deflectometer per ASTM D4694 to measure surface deflections at 9,000 lbf. Data are backcalculated to determine layer moduli (E1, E2, Mr) for overlay design.
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Coring & Layer Thickness Verification
Extraction of full-depth cores (4-inch diameter) at 500-ft intervals to verify asphalt and base thicknesses, delamination, and moisture condition. Cores are logged and photographed for forensic documentation.
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DCP & Subgrade Strength Profiling
Dynamic cone penetrometer testing at 1-ft depth increments to obtain penetration index and estimate CBR. Used to map weak subgrade zones, especially in areas with expansive clay from the Cajon Pass formation.
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Laboratory Soils & Materials Testing
CBR (ASTM D1883), resilient modulus (AASHTO T307), and moisture-density relationships (ASTM D698) on subgrade and base samples. All tests performed in an ISO 17025-accredited laboratory.
Relevant standards
ASTM D4694 (Falling Weight Deflectometer), ASTM D4695 (Pavement Deflection Measurements), ASTM D1586 (Standard Penetration Test & Sampling), ASTM D2487 (Unified Soil Classification), AASHTO 1993 Guide for Design of Pavement Structures
Quick answers
What is the typical range for an existing pavement evaluation in San Bernardino?
The final price depends on the number of test points and the need for additional forensic coring.
How long does an existing pavement evaluation take from start to report?
Field testing for a typical 1-mile section takes one day. Laboratory testing adds 5 to 7 business days. The final report with backcalculated moduli and overlay recommendations is delivered within 10 business days after field completion.
What is the difference between FWD backcalculation and DCP profiling?
FWD backcalculation provides in-situ layer moduli (E1, E2, Mr) using deflection basin matching, ideal for structural capacity assessment. DCP profiling gives a continuous strength profile with depth, useful for identifying thin weak layers or moisture-sensitive zones that affect subgrade support.
Can an evaluation be performed on a road with active traffic?
Yes. FWD testing is non-destructive and can be conducted under rolling lane closures with proper traffic control. DCP and coring require stationary lane closures of 15 to 30 minutes per location. We coordinate with local traffic management and use advanced warning signs per Caltrans standards.
