(Source: AP via Forbes.com)

An older idea is experiencing a rebirth thanks to the truck traffic that increasingly chokes America’s highways: shift more of U.S. freight burden to boats that can traverse rivers, lakes, canals and coastal waters.

Increased concerns about fuel prices and global warming in recent years have revived interest in marine highways from the Erie Canal to the Chesapeake Bay to the coastal waters off Oregon, Massachusetts and Texas.

Proponents envision further expansion of the country’s 25,000 miles (40,230 kilometers) of navigational waterways by making greater use of the coasts and inland routes, such as the St. Lawrence Seaway (other-otc: STLS.PK – news –people ), the Great Lakes and the Mississippi and Ohio rivers.

A significant expansion of the marine highway system faces several obstacles:

Many locks haven’t been updated in decades to accommodate increased freight traffic. Replacing America’s lock system would cost an estimated $125 billion.

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