You Asked: What do numbers mean on beams of Kentucky River bridge?

Josh Bergeron / State Journal – Numbers span the length of a structural beam on the West Frankfort Connector bridge over the Kentucky River. The numbers indicate the amount of vertical clearance above the marker.

Starting at 45 and ending at 15, numbers painted on beams beneath the inbound and outbound West Frankfort Connector bridges over the Kentucky River provide boaters with an estimate of vertical clearance.

A reader asked about the meaning of the number markings on the U.S. 421 bridge (also the West Frankfort Connector) and whether they represent flood levels.

The Kentucky Transportation Cabinet said the numbers are clearance gauges for boats to use as well as showing the height of the water.

Emergency Management Director Tommy Russell also said the numbers represent clearance heights.

“So, if the water is up to the 30-foot number, that means there’s 30 feet between you and the bottom of the bridge,” Russell said.

Water that reaches No. 25 means boaters have 25 feet between the river and the bottom of the bridge and so on.

Russell said that the clearance  beneath the bridge isn’t often an issue, as most traffic on the Kentucky River is recreational, but the numbers likely are used when cranes are brought onto the Frankfort section of the Kentucky River for dredging.

Russell said he’s only needed to reference the numbers when the Kentucky River is in flood stage and a boat is loose, floating down the river.

On Thursday afternoon at 1:30 p.m., the Kentucky River at lock No. 4 was 8.39 feet. Flood stage is 31 feet.

Gauge height, or stage, is the height of the water in a stream or river above a specific reference point, according to the U.S. Geological Survey. It doesn’t refer to the depth of the stream.

The highest crests, as measured at Lock No. 4, have been 48.47 feet on Dec. 10, 1978, 47.46 feet on Jan. 25, 1937, and 45.22 feet on March 3 1997.

But numbers at Lock No. 4 function opposite of the numbers painted on the Kentucky River bridge, decreasing as the river rises to indicate a lower clearance.

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