WPBD vs Knex - Hudson

Both of these tools are extremely fun and useful to build bridges. WPBD is semi-hands on in its approach in that there aren't many set designs to choose from, but building with the Knex allows you to really understand the difference in bridge strength.
WPBD and Knex are similar in that, in a way, you can understand how strong the bridge is that you made with each of them. They both also allow easy corrections and fixes.
WPBD is superior to Knex in that it tells you where your bridge will break, if it's a feasible idea, and the relative ratios on each member. WPBD also allows angles and thinner/thicker members that Knex does not. Knex are superior in that they allow you to actually feel the bridge you're designing and you can see how the pieces are going to break when they do and try to design around that instead of just making that member larger and stronger, because it's usually not the member that breaks, it's the joint.

Overall, I think both the WPBD software and Knex are good ways to get a feel for your bridge and understand how it works.

WPBD vs. Knex - Lester

The West Point Bridge Designer is a very useful program for realistic bridge modeling. It has informative stress test simulations and takes multiple factors into account when calculating cost (like material type, length, and density). Members can be any size, made from one of three materials, and can be hollow or solid. Design aspects such as these are chosen at the user’s discretion. All connecting pieces are the same size and weight, but can connect at any angle and it is possible to connect a great number of members to one connecting piece in the drawing board. Only one side of the bridge can be modified. The parallel side is exactly the same and the perpendicular connecting pieces are created by the program.

K’nex bridges are very different. K’nex pieces are all made from the same solid plastic material. There is a limited variety of members each at a difference, set size that cannot be changed. If one piece is too short and the next biggest piece is too big, then it is impossible to find a member that will fit that space (unlike in WPBD). Connector pieces, known as gussets, are different as well. They have a certain amount of slots at specific angles that fit the member pieces. The K’nex kit has more artistic freedom than the WPBD, since with K’nex a design doesn’t have to be symmetrical on both sides and the perpendicular connecting pieces can be drafted by the user.

There are a few similarities between the two. Both use straight members that can bend a bit to support a design up to a certain breaking point. They have the possibility to create different shapes not limited to triangles, like pentagons, hexagons, etc. The products of both can be weight tested to determine bridge strength. Overall, the two methods are vastly different, yet the outcomes can be very similar. The bridge I designed on WPBD and the K’nex bridge I designed look somewhat similar to each other.

-Belinda Lester

WPBD vs. K'NEX - Durkin

K'NEX are a great hands on way to understand the structure of a bridge, in the same way that WPBD is a great way to learn about bridge structure.  Both use the basic ideas of joints and members in the construction of a bridge and both are great educational tools however past that there are very few similarities. A bridge built from K'NEX cannot bend in the same way that the bridges in WPBD can nor does a K'NEX bridge analyze the stress points in the way that WPBD does.  K'NEX also falls short in the types of members available as one cannot adjust the thickness of the members or the materials they are made from. One aspect of K'NEX that is not an option in WPBD is the ability to use different types of joint.  WPBD also does not allow for 3D changes in the way that K'NEX do. For example with K'NEX changes can be made to how the two sides of the bridge attach to each other, WPBD does not allow for this. Due to the lack of information K'NEX give about their weak points and how best to attach things a lot of this week will be spent testing different joints, attachment, and lengths of members in the hopes of building the most cost efficient bridge.