For centuries, bridges have gotten people from here to there. Craftspeople and designers have developed seven popular types of bridges to carry our loads.

Suspension Bridge: This type of bridge can stretch longer than any other bridge. Its deck hangs from strong wires called cables. The cables are anchored to large towers which carry the weight to the ground. These bridges wiggle. That’s because the cables move when the bridge meets pressure from wind.

Arch Bridge: This bridge is often made from stones or bricks. Arch bridges have supports on each end called abutments. Arch bridges are simple but can carry heavy weight. A masonry arch always has a center stone or brick at the very top. It’s called a keystone.

Beam Bridge: This is the simplest and oldest type of bridge. Beam bridges are horizontal and level. They have a support on each end. They cannot span very great lengths because they may begin to sag in the middle without additional support.

Cable-Stayed Bridge: For this kind of bridge, towers called pylons hold the bridge’s weight. Cables connect the bridge deck to the towers. The bridge’s cables create a fan-like pattern.

Cantilever Bridge: Two beams stretch toward one another to form a cantilever bridge. The beams look like diving boards. Cantilever means to stick out. One end of a cantilever is anchored in the ground. The other end reaches out away from the support to form the bridge.

Truss Bridge: This strong bridge has a support at either end. A frame connects the two ends of the bridge. The frame is usually made up of lengths of wood or metal that forms several triangles. Triangles make a structure sturdy. The frame forms a tunnel.

Tied Arch Bridge: These bridges are usually metal. Ties hold the bridge support in an arch shape. The deck is sometimes the tie that holds the support in its curved shape.

Jesus, Our Keystone:

The keystone is a wedge-shaped stone at the very top of an arch bridge. It is the final stone laid into place when an arch bridge is built. The keystone locks all the other stones into place. It presses outward, making the other stones press equally into each other. There is only one keystone in an arch bridge. Jesus is our keystone. He holds all things together perfectly. Colossians 1:17 says, “And He is before all things, and in Him all things hold together.” 

Build an Arch Bridge:

Supplies: Cardboard or card stock, scissors, tape, marker

Step 1: Cut out seven identical trapezoids from the cardboard. They must have three equal sides. The fourth side must be ½ the length of the other three sides. (ex: 1 inch x 1 inch x 1 inch x ½ inch)

Step 2: Tape each of the seven shapes together to form an arch. The shape in the middle is the keystone. It is at the very center and top of the arch. Draw a cross on the keystone.

Step 3: Cut out two six-inch by three-inch strips of cardboard.

Step 4: Fold one strip in four equal parts to make a cube. Tape the cube together. Repeat with the second strip. (You should now have two cubes.)

Step 5: Tape one cube to either side of the arch. The cubes are called abutments. The abutments hold the pressure sent out from the keystone. They are compressed by that pressure. They support the bridge.