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Beam Bridge 
You could build a continuous-span beam bridge across the river and it might
even be your cheapest option. But what about all those barges? They'll never
fit between the piers. Try again.Photo: Portland Cement Association NOVA Builds a Rainbow Bridge | Bridge the Gap | Nature's Miracle Material China's Age of Invention | Resources | Transcript Medieval Siege | Pharaoh's Obelisk | Easter Island | Roman Bath | China Bridge | Site Map Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule About NOVA | Teachers | Site Map | Shop | Jobs | Search | To print PBS Online | NOVA Online | WGBH © | Updated November 2000 |