Covered Bridge Builder Game
HOW TO PLAY
The easy way to play is to simply click on a link to one of the example bridges (see below, or from the home page).
As a vehicle goes over the bridge the truss changes color 
. The color changes from shades of green to red. The closer it gets to red the more critical the stress on the truss. If the truss reaches its maximum capacity, it will fail and fall into the river. Once one truss goes, the rest of the bridge will soon follow.
Ask yourself the following questions:
(1) Is the bridge more likely to last if there are 19th. century vehicles or 21st. century vehicles?
(2) Is a kingpost truss better for longer or for shorter bridges?
(3) Is the multiple kingpost truss stronger than a lattice-plank truss?
To play, click one of the bridges below, when the window opens, click on Run 
. Click on Stop to pause the simulation. Click on Home 
to try a different bridge.
Examples with 19th. Century Vehicles
Play with a Multiple-Kingpost truss covered bridge
Play with a Queenpost-Multiple-Kingpost covered bridge
Play with a Lattice Truss covered bridge
Examples with 21st. Century Vehicles
Plot
As the simulation plays, a separate window shows a graphic plot of the load on the bridge (you may have to click on the Window menu of the browser to see the plot).
The higher the green line, the greater the load on the bridge. The red line shows the maximum weight this bridge can support. If the green line crosses the red line (as in the example above), the bridge will break apart. You can change this value by changing the simulation properties (see below).
Simulation properties
If you select simulation properties in your game 
the following window opens. This window allows you to change many values used in your bridge. The numbers used are an approximation of pounds. What is important here is to see the relative effect of changing one value or another.
You can change the capacity of the bridge (max_capacity). The higher the number, the more vehicles it can hold. You can also change the capacity of any one truss (truss_limit), or you can change the weight of any of the various vehicles. Make a truck heavier, for example, and see how well your bridge works.
At any time you can return to the original values of the simulation by clicking on Reset 
in the simulation.
Yes, you can build and test your own covered bridges! It's actually quite easy.
Click here to build your own covered bridge, or read on.
How this program works:
(1) To add a bridge part or abutement to the worksheet click on the pencil 
, click on what you want, such as the abutement 
, then click where you want it to appear.
(2) To erase, click on the eraser 
, then click on what you want to erase.
(3) To move something. Click on the pointer 
, then click-hold-and-drag the item you want to move, such as the abutement.
Bridge-building basics:
(1) First, build your abutements .
(2) Make sure you have a 19th. century sign or a 21st. century sign on the
road to the left of your worksheet.
(3) Make sure there's a green tree on the road on the right of your worksheet
.
(4) Add your bottom chords
. There has to be a bottom chord (which is what the vehicles travel on).
(5) Add your trusses 
. From approximately the center of your bridge you will want the 45 degree braces to point (lean) towards the abutements.
(6) Add your top chords, 
, (which holds the brace in place).
Click on RUN to run your simulated bridge, or Stop to stop it.
Here is an example of a finished bridge. You can also decorate your bridge with a roof and a portal at each end. For the purpose of this simulation the roof and portal have no function.
