Baltimore sits on a complex sequence of Coastal Plain deposits — sands, silts, and clays that transition sharply into weathered schist and gneiss near the Piedmont fall line. With over 585,000 residents and a dense urban grid of aging asphalt and concrete surfaces, the need for a thorough existing pavement evaluation in Baltimore is clear. We rely on Falling Weight Deflectometer (FWD) testing per ASTM D4694 to measure layer moduli, and we back it with plate load tests to confirm subgrade reaction values. Without this data, decisions on overlay thickness or full-depth reclamation are guesswork.
A CBR of 3.2 percent on Lombard Street forced a full redesign — that is why we core and test every section.
Method and coverage
Regional considerations
The biggest risk in Baltimore is the variable transition from deep clay to shallow rock within a single block. In Hampden, we found 3 meters of soft clay over weathered mica schist — the clay was compressible, the schist was strong, but the interface caused differential settlement at every joint. Missing that transition leads to reflective cracking within two winters. An existing pavement evaluation in Baltimore must include continuous profiling, not just spot tests. We always run at least one DCP or GPR line per lane to catch these transitions.
Standards that apply
ASTM D4694 (FWD deflection), ASTM D1196 (non-repetitive plate load), ASTM D1883 (CBR), AASHTO T 256 (pavement deflection)
Related services
FWD and Plate Load Testing
We run Falling Weight Deflectometer surveys on arterial and residential streets, applying back-calculation of elastic moduli. For small areas or concrete slabs we use plate load tests per ASTM D1196 to get the k-value directly.
Pavement Coring and Layer Sampling
We extract 100 mm diameter cores through asphalt and concrete, measure thickness, and log visual condition. The cores are used for lab density and moisture content; we also recover subgrade samples for classification and CBR.
DCP and GPR Profiling
Dynamic cone penetration gives us a continuous strength profile of the subgrade every 10 cm. Ground-penetrating radar maps layer interfaces and detects voids or utility trenches that could cause premature failure.
Typical parameters
Common questions
How much does an existing pavement evaluation in Baltimore cost?
For a typical project of 10 test locations including FWD, coring, DCP, and lab CBR, the range is between US$1.150 and US$3.740. The final cost depends on the number of cores, traffic control requirements, and whether you need full structural number calculation or just deflection data.
What is the difference between FWD and DCP testing?
FWD measures the deflection response of the entire pavement system under a simulated wheel load, which lets us back-calculate layer moduli. DCP gives a direct penetration index of the subgrade strength at depth. We use FWD for structural capacity and DCP for subgrade variability.
When should I use GPR instead of coring?
GPR is best when you need continuous layer thickness maps or want to locate buried utilities without cutting the pavement. It does not replace coring for strength or density data. We often run GPR first to plan core locations, then core at spots where thickness changes or anomalies appear.