Engineers with the Kentucky Transportation Cabinet have stepped up efforts to monitor the old Ledbetter bridge after detecting an additional inch of movement in its west approach spans Wednesday.
The Kentucky Transportation Research Center will send a seismic sensor to alert inspectors to major movement in the bridge's sagging approach spans. The sensor is expected to arrive today for installation, cabinet spokesman Keith Todd said.
"Most of the movement (of the bridge) has been gradual. If there is a major bump, the sensor gives us a heads up to get out and check the rest of the span," Todd said.
Nearby resident Bill Schroeder offered to supply power to the sensor until it could be attached to a more permanent supply, Todd added.
The additional movement came after the area received about an inch of rain in a 24-hour period. The spans have moved about 3.25 inches in the past three days.
"If it stops raining and dries up, we think it will stop moving and we'll be OK," he said.
The National Weather Service said Wednesday that precipitation chances would fizzle by nightfall, with only scattered showers expected through Friday, according to meteorologist Rachel Trevino.
"It's all uphill from here," she said. "The big rain was (Wednesday)."
McCracken County Emergency Management Agency officials touched base with residents near the bridge to remind them to stay alert for signs of land moving along the bluff, but did not order any evacuations. Director Jerome Mansfield was returning Wednesday from a disaster planning conference in Lexington to continue monitoring the area, Todd said.
Mansfield did not immediately return calls seeking comment.
Todd said engineers have been monitoring the bridge, which spans the Tennessee River from McCracken to Livingston counties, every few hours since it dropped about 2 feet on April 30.
The 83-year-old bridge has been closed to motor traffic since last July when the new Ledbetter bridge opened, but its stability is still a concern for river traffic, Todd said.
An earlier assessment of the bridge showed a collapse of the approach spans wouldn't likely affect the main truss over the Tennessee River navigation channel.
But engineers continue to monitor the spans and negotiate with contractors to expedite demolition. Solar-powered navigation lights were placed on the main span and piers in case an approach span collapse cuts power to the bridge, Todd added.
Sun reporter David Zoeller contributed to this report.
Contact Laurel Black, a Paducah Sun staff writer, at 270-575-8641, or follow @LaurelFBlack on Twitter.