To keep the design of floating Bridges safe and economical, a relatively precise evaluation on the Bridges' loading capacity and strength is necessary.

为了使浮桥的设计既安全又经济，就必须对浮桥的载荷和强度有一个比较精确的评估。

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It also means that spare pallets take the most economical route from a retailer's loading dock back to a warehouse or factory that is shipping out goods.

FORBES: Beast of Burden