Here at Foresight, we are 100% committed to the success of both you, our Prime firm, and the entity you’re serving. Your clients want both cost and schedule success in each phase, from design through construction. We want that for them as well.
We are hired to solve problems. One of the tenets Foresight hangs its hat on is just that…foresight. If we didn’t believe that every line item in our budget would help your client, we’d remove the useless ones before it was sent to you.
We believe Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) are nearly always beneficial to your client when designing pavement.
Your client’s dilemma
Your client deals with the pressure to reduce pavement design budgets: FWD and GPR are often considered “nice to have but not necessary” and are added to the chopping block while traditional borings (which only offer a snapshot) are kept.
How can FWD and GPR help my client?
FWD gives a full build time profile of the various layer modules. We combine that data with GPR that picks up pavement thickness and section thickness across the entire length.
Borings can be effective…but do they give the full picture?
A typical boring is a 3-inch hole and can be spaced every 1000LF or 2000LF on average. That’s equivalent to two ½”-wide holes over the length of a football field.
To minimize impacts to traffic, we typically drill on the shoulders or in the median;
shoulder thickness can be different than main lane thickness, and there’s no pavement thickness in the median.
Non-destructive testing such as FWD and GPR are less invasive to the traveling public and provide a full look at your pavement segment. Gaps in boring coverage, combined with a desire to limit long term lane closures, means your client may not get the information they need.
Most other aspects of design now use these 3D datasets of existing conditions (think OpenRoads) to best reduce surprises in the field during construction.
How FWD & GPR saved one client over $500k
We recently provided geotechnical and pavement design services on an urban project. During design, FWD and GPR were removed from the scope in lieu of much cheaper traditional borings spaced at 2000 feet.
6 months after borings were drilled, original as-builts were pulled showing asphalt overlaying concrete pavement, and none of our borings picked this up due to the large spacing.
This data deficiency impacted quantities and the demolition budget for the construction phase since the contractor needed to know (for bidding purposes) whether he needed to rip up asphalt or rip up both asphalt and concrete.
FWD plus GPR were then done at the owner’s request, costing less than $20,000.
The newly-acquired data saved upwards of $500,000 of construction cost.
Our Expert Recommendation
We’re all for reducing project costs. However, we’ve found that cutting FWD and GPR during design significantly increases future construction risk for costs and delay claims.
Within our combined 45+ years of GEO experience, at least 30% of our past projects could have saved more than the initial cost of FWD/GPR based on the amount of extensive construction cost and schedule impacts that occurred.
Without FWD and GPR it can be difficult to find what’s outside of 3-inch holes every 2000 feet. With FWD and GPR, both you and your client can be heroes at the end for reducing unforeseen issues at the beginning.