The Otoe County Sheriff's Office says a "crude, improvised device" was placed on the railroad tracks to diminish warning signals at an intersection with a county road.

Sheriff's Deputy Greg Kotschwar said the device effectively delayed the crossing signals until the train was only seconds away from the roadway. He warned motorists to take extra precautions at railroad crossings.

Union Pacific signal operators in Omaha noticed a brief triggering of the lights around 10:30 p.m. on Labor Day and sent a crew to investigate.

The Otoe County Sheriff's Office and the Union Pacific Railroad are investigating the placement of an improvised device on railroad tracks intended to sabotage the warning lights at the intersection of Goosehill Road north of Nebraska City.

Deputy Sheriff Greg Kotschwar credited the Union Pacific signal operators in Omaha for noticing an unusual and short-lived signal disruption on the railroad line around 10:30 p.m. on Monday.

The warning lights triggered for a moment, but since there was no train in the area, a maintenance crew was dispatched to investigate.

Kotschwar said "a crude, improvised device" was found attached to the tracks with the apparent purpose of diminishing the effectiveness of the warning lights and signals.

Normally, an approaching train would trigger signals at the intersection while the train was 1,500 feet away. The improvised device disabled the normal trigger, so the warning signals would not trigger until the train was 300 feet away.

"It altered what happened to the signal at that crossing. There would only be a few seconds between the time the signal went off and when the train entered the intersection," Kotschwar said.

The deputy said railroad agents told him that the device was likely constructed by someone who knows how the signals operate, but he said he does not know what motive the saboteur might have had.

Kotschwar said this is the only case of this happening in Nebraska and raises serious safety considerations.

"It certainly was and would have been effective had a train came through," he said.

The sheriff's office is asking anyone who saw activity near the tracks on Monday or seeks people tampering with tracks to call the sheriff's office.