MILWAUKEE, Wis. (WTAQ) - The largest road building project in Wisconsin history is only 2 years old – and already, there are cracks in it.

An on-ramp at Milwaukee’s Marquette freeway interchange was shut down Thursday night, after cracks were found in a vertical support column.

State Transportation Secretary Frank Busalacchi said the 40 foot support was not designed properly, and it’s not strong enough to support the roadway and the steel girders that rest on it.

The cracks were found during a routine inspection on Monday. Busalacchi said the design firm of HNTB is taking responsibility for the problem, and will fix it. The extent of the repairs is not known – and neither is the amount of time it will take to get things resolved.

Busalacchi said the ramp is not in danger of falling. It’s located off Wisconsin Avenue at 11th Street, and it takes traffic onto southbound Interstate 43. The ramp normally carries around 15,000 vehicles a day – and they’ll be detoured to another on-ramp.

The Marquette Interchange is the crossroads of Interstates 43, 94, and 794 in downtown Milwaukee. It was rebuilt in a four-year period, at a cost of $800 million. Its status as the largest road project in state history will soon be surpassed by the expansion and rebuilding of I-94 from Milwaukee to the Illinois state line.