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The effects of time take a terrible toll on highway infrastructure, and an area of heavy travel in mid-New Castle County had its number called when ground was recently broken, quite literally, to erase the damage it had sustained.

The deterioration of the median barrier on Delaware Route 1, or SR-1, at Tybouts Corner prompted the Delaware Department of Transportation (DelDOT) to zero in on the sweeping jug-handle interchange at US-13/South DuPont Highway.

Tybouts Corner Median

The north end of the Tybouts Corner jug-handle interchange on Delaware Route 1, at US-13/South DuPont Highway. The median barrier was being replaced with a thrie-beam guardrail, due to deterioration of its concrete properties.

Specifically, engineers had determined that the concrete properties of the raised median, at the north end of the jug-handle, had outperformed its useful life due to weathering characteristics consistent with alkali-silica reaction, or ASR.

"It's a reaction between the cement and aggregates within the concrete, given sufficient moisture," explained Andrew Short, DelDOT Design Engineer. "Over time, it will cause expansion and eventually lead to loss of strength and failure."

What amounts to an eye-test by engineers revealed spalling, or surface failure caused by freeze-thaw cycles, and the exposure of its rebar foundation in spots. That degradation prompted the replacement of the concrete barrier to a metal guardrail, extending all the way to just south of the US-40/Pulaski Highway interchange.

Tybouts Corner Concrete Median Spalling

The spalling characteristics of a portion of the median barrier, located on SR-1 at Tybouts Corner. Spalling, or alkali-silica reaction, is surface failure caused by moisture which negatively affects the physical properties of concrete.

"The installation of the guardrail in this location is more cost efficient and still meets our safety needs," Short revealed. "We're going with a thrie-beam guardrail because it meets our deflection needs, therefore eliminating the need to widen the median and reduce additional shoulder reconstruction."

The entire interchange had been considered for improvements but, because of the lack of funding and absence of a working timetable for those enhancements, the median barrier replacement was one aspect that could not be postponed.

"Right now it's more of a safety issue, so we need to replace it as soon as possible."

The project, which was to be completed, pending weather, by May 26, 2017, would deal lane shifts to northbound drivers, between US-13 and US-40/Pulaski Highway, as well as place detours for southbound travelers at the interchange.