DOT lapses led to botched I-40 project

State left out crucial written directions to the contractor; paving repairs will cost $18.6 million

A yearlong internal review at the state Department of Transportation sheds light on far-reaching failures that came together in an $18.6 million blunder on Interstate 40 in Durham County: Next year 10.6 miles of crumbling concrete will be ripped out and replaced with asphalt.

The paving was botched because DOT engineers gave faulty instructions to the contractor. The new DOT study, summarized in a 67-page report, tracks their costly mistake through several years and across many desks at the state's road-building agency:

* DOT pavement experts did not know much about bonded concrete overlay, a paving process rarely used in North Carolina, when they chose it in 1999 for a major project to relieve congestion on the Triangle's busiest freeway.

* Engineers who drafted paving instructions for the $44.8 million contract in 2001 lifted the bonded overlay details from plans for a small Raleigh Beltline paving job. They thought -- mistakenly -- that it was similar to the big I-40 project.

* The DOT did not give its engineers any training in the new paving method until October 2003, five months after overlay paving began on I-40. The department did not update its technical manuals to include the special requirements of overlay work.

I-40 commuters remember the chaos and congestion they endured during the three-year widening project between Chapel Hill and Research Triangle Park. They could face more of the same next spring when the DOT begins pavement repairs that will continue into 2008.

The DOT plans to remove a 3-inch layer of concrete from the two outside lanes in both directions -- about 50,000 tons of bad concrete that should have been good for 30 years.

"There's never been a project or a situation that I know of in my career with DOT as disappointing as this is," said Len A. Sanderson, the state highway administrator, in an interview Tuesday.

Sanderson's DOT career began in 1970. Transportation Secretary Lyndo Tippett signaled its end Friday, announcing that Sanderson, who has supervised 11,000 DOT employees since 1998, would retire Jan. 1.

The I-40 concrete, put down in 2003 and 2004, began breaking up in the summer of 2005. Tests showed that state and federal engineers, contractors and inspectors had overlooked a crucial detail in the paving process -- the right way to cut expansion joints between slabs of concrete.

Sanderson directed the DOT's internal investigation and delivered its findings to Tippett last month. The report describes a string of blunders.

Sanderson's report also looks at frequent accidents and poor drainage on the I-40 project. Because engineers underestimated the need for drains along the median, the DOT spent an extra $1.8 million to repair water damage and install additional drains.

Shallow expansion joints

The I-40 paving failure called into question the choice of the bonded overlay method, but pavement experts elsewhere say it has succeeded on the Beltline and on bigger projects in other states.

It involved a 3-inch layer of concrete poured over the two original concrete lanes each way that had carried traffic since I-40 opened in Durham County in the 1980s. (The DOT used standard paving methods to add a third lane in each direction, in the original median.)

The concrete layers were supposed to bond as a strong, single layer. The secret lay in carefully sawing expansion joints through the full depth of the top layer, making room for the concrete to expand and contract with changes in the weather.

I-40 engineers, contractors and inspectors discussed full-depth joint cuts only once -- in April 2003, shortly before the bonded overlay work began. DOT officials say they gave clear direction that day but acknowledge that they violated their own policies by failing to put it in writing.