KENNEBUNK (AP) – A one-week construction schedule and spotty structural data on a bridge that passes over railroad tracks used by Amtrak’s Downeaster contributed to its buckling during a track overhaul, the project manager said.

“With unlimited time and no train service we could have gathered more information, but those are not things we had the luxury to do,” Maine Department of Transportation project manager Paul Pottle said. “There’s no guarantee even with more site information we could have predicted what happened.”

The 72-year-old span carried traffic along Route 35 between Kennebunk and lower Kennebunk over the tracks of one of Maine’s busiest rail lines.

The railway renovation was meant to firm the ground beneath the tracks so trains could move along that section at speeds higher than the current 25 mph speed limit.

The bridge buckled after work to excavate clay beneath its supports apparently caused the clay to liquefy, Pottle said.

Trying to complete the $900,000 project in one week was a “very aggressive schedule,” Pottle said. With more time, engineers could have done more soil tests that could possibly have let them anticipate such problems.

Workers hoping to shore up the bridge last week were stymied by old records that provided incorrect specifications. The stones used in abutments were smaller than those shown in blueprints, and were not placed where the records indicated.

“We had very limited information on what was holding the abutments up,” Pottle said.

Engineers hope to have a prefabricated, military-style bridge in place within two weeks, and preliminary designs for a replacement bridge are already in the works. MDOT would like to begin work on the permanent structure by the end of the year, Pottle said.

Transportation officials plan to study the incident to find out just what caused the bridge to buckle, but fault finding is unlikely to result, Pottle said.

Amtrak trains will roll on the tracks beneath the bridge on Sunday as scheduled, though a bus may substitute for the train north of Wells.