Bridge Challenge
Craggy Rock, a growing community, needs four new bridges, and they're very picky about what they want! Each bridge can only be
used once. Read through the requirements for each bridge and record the needed bridge in the chart. For additional assistance you
can go to the web page: http://www.pbs.org/wgbh/buildingbig/bridge/challenge/index.html
Location1: Build a multi-lane bridge for commuters and tourists Span: 2,000 feet Crossing: River
highway
Connects: City and major
Special Notes:
"I want a one-of-a-kind bridge that will span our beautiful river and welcome visitors from all over the world to our thriving city.
Make sure the new bridge leaves enough room for sailboats on the river. Please don't build a bridge that looks like the Golden Gate
Bridge in San Francisco or the Brooklyn Bridge in New York." -- Mayor of Craggy Rock
What kind of bridge should you build?
A. Beam B. Suspension
C. Arch
D. Drawbridge
Location 2: Build a bridge for rollerbladers and bikers Span: 100 feet Crossing: Stream Connects: Two bike paths
Special Notes:
"We're tired of getting bumped off the road by angry drivers! We want a simple bridge -- one that will connect the bike paths in East
and West Craggy Rock over the city stream. We don't have much money, so we're not asking for much. We just want to get to work
every day without risking our lives!" -- Craggy Rock Bike-n-Blade Coalition
What kind of bridge should you build? A. Beam
B. Suspension
C. Arch
D. Drawbridge
Location 3: Build a highway bridge across a busy shipping port Span: 5,000 feet Crossing: Ocean bay Connects: Island and
mainland
Special Notes:
"Our records indicate that more than 500 ships pass through Craggy Rock Harbor each day. Please build a bridge that does not block
the flow of water traffic. We do not want angry sailors or congestion of any kind in our harbor. Thank you." -- The United States
Coast Guard
What kind of bridge should you build? A. Beam
B. Suspension
C. Arch
D. Drawbridge
Bridge Challenge
Location 4: Build a railroad bridge in a national park Span: 500 feet Crossing: Deep river gorge Connects: Two rocky bluffs
Special Notes:
"We do not want the new bridge to detract from the natural beauty of Craggy Rock National Park. Please build a simple and elegant
bridge -- one that does not have towers or piers." -- The National Park Service
What kind of bridge should you build? A. Beam
B. Suspension
C. Arch
D. Drawbridge
The mayor has several complaints about the four proposed bridges. Select a possible solution for each concern. Record the solution
on the response sheet.
Beam Bridge: When it rains, the city stream rises. A really strong storm could cause flash floods, turning the stream into a raging
river. Piles of rocks and a wall of gooey mud could push on the piers of the concrete beam bridge and cause it to topple. Luckily, you
can fix it before that happens!
How will you build a new, flood-proof bridge?
A. Build deeper piers
B. Build a higher deck
C. Use stronger material
Suspension Bridge: Your new bridge is moving up and down a lot in the wind! This isn't a big problem under normal conditions, but
what if a hurricane were to blow through town? It could cause the bridge to move too much, or even twist so violently that it would
snap in half!
How can you strengthen the bridge to resist strong winds? A. Stiffen the deck with an open truss B. Stiffen the deck with a solid
steel girder C. Make the bridge narrower
Arch Bridge: Twenty years have passed. You're an older, wiser, and wealthier engineer. The phone rings. It's the National Park
Service. Chunks of concrete are falling from the arch bridge into the gorge. Twenty years of cold weather have chewed away at the
bridge. It's time to replace the cracking concrete with a new material.
Which new material will you choose? A. Wood
B. Steel
C. Steel
Drawbridge: In one of the rowdiest town meetings ever, the residents of Craggy Rock spoke out against the new drawbridge. "It's
ugly," one angry resident said, "and there's always traffic on the bridge. They open it for boats, but what about us? We have to get
to work, too!" The mayor is begging you to build a new bridge. The local steelworkers are on strike, so she advises you to build a
bridge with as little steel as possible.
What would be the best alternative? A. Cable-stayed bridge
B. Cantilever bridge
C. Combination Arch and Beam bridge