Not all forensic investigations involve buildings or structural systems that have failed. This particular project, provided for a family whose historical home was constructed on peaty soft saturated soil conditions, involved evaluating the most cost effective means for isolating the residence from severe vibrations caused by frequent heavy truck traffic passing within approximately 50 feet of the front of the residence.

The investigation included a structural evaluation of the two-story wood framed residence, a geotechnical study of the sub-surface soil conditions, and an experimental vibration test involving heavily loaded gravel dump trucks.

The project conclusions exceeded the owners' expectations in that essentially all noticeable vibrations were mitigated through speed control of the heavy trucks. Project recommendations were generally limited to localized improvements and a maintenance plan for the existing dirt road in front of the residence, as well as speed control signage for passing traffic.

Structure Foundation
Porch Foundation
The Residence

Project Type
Forensic Investigation - Structural Vibration Study

Forensic Investigation Completed
April 29th, 2011

Estimated Completion of Construction
Summer 2012

Building Jurisdiction
The County of Solano

The historical residence was constructed on a pressure-treated timber foundation resting directly on the surface of the peaty soft saturated soils. A geotechnical investigation at the site revealed that suitable bearing soils were not present to depths exceeding fifty feet and the groundwater elevation was frequently recorded at ground surface.

The project conditions undermined most typical means of structural vibration isolation, which inspired the development of the traffic speed/load experiment that ultimately lead to the successful mitigation of the structural vibrations.