BERTHA
Click on the links below to learn more about Bertha and the new SR99 tunnel that Bertha built. At the bottom of the page, there is also an experiment you can do to learn about how arches work, a technology used in the construction of Bertha’s tunnel.
This is Bertha before she began drilling the tunnel. To better understand her enormous size (5 stories tall!), find the man in the picture. HINT: He is on the bottom right. Can you spot his white helmet? Photo credit: WSDOT
To find out more about Bertha, visit this WSDOT site: Bertha.
YouTube link to an animation of how Bertha dug the tunnel visit: Bertha in motion
YouTube link to a video about the smart features of the SR99 Tunnel: Smart Tunnel
EXPERIMENT
Build your own arch!
How much stronger is an arch than a flat roof? Try this experiment to find out.
Supplies:
small box, such as a shoe box
several sheets of thin paper; plain printer paper or construction paper works great
a bunch of coins such as pennies
scissors
1. Build a flat roof by placing one sheet of paper across the top of the open box.
2. Place coins, one at a time, on top of the paper. How many coins can the roof hold before it collapses? Record your answer.
3. Build an arch by bending a piece of paper into an arc and placing the ends of the paper on the inside walls of the open box. You may need to trim your paper to the right width to make it fit.
4. Place coins, one at a time, on top of the arch. How many coins can your arch hold before it collapses? Record your answer and compare it to the flat roof results.
5. Build a double arch by removing the piece of paper and cutting it in half. Make two arches by bending the papers into arcs and placing them side by side inside the box to make them stand up next to each other.
6. Place a third piece of paper on top of the arches for a platform. How many coins can your double arch hold?
7. Try making a triple or a quadruple arch platform. How many coins can it hold? Can it support a banana? How about a book?