Culverts on the Alexandria - Ashland Highway (AA Highway) were designed with modifications recommended in a 1984 report titled "Analysis of Loads and Settlements For Reinforced Concrete Culverts". In 1986, the Kentucky Department of Highways requested the Kentucky Transportation Center monitor selected culverts on the AA Highway. The objectives of this study were to compare predicted loads on the culverts to measured loads and to monitor differential settlement of the embankment near the culvert.

Four culverts with varied box dimensions and embankment heights were selected. Each of the four culverts was instrumented with earth pressure meters on the sidewalls and top slab. Settlement monitoring instruments were placed in the embankment at each culvert.

Design loads for each culvert sidewall and top slab were calculated. Design loads and dead loads due to the weight of the embankment were compared to the measured loads. The new design method used by the Department of Highways was found to be very accurate for predicting top slab loads on positive projecting culverts on unyielding foundations. The Department of Highways method significantly underpredicted the top slab load for a culvert on a yielding foundation.

The Department of Highways does not include charts from the 1984 report for predicting sidewall loads. Charts from the 1984 report appear to be reasonably accurate, especially as sidewall loads increase.

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