Our company, Akiyama-Kensetsu, is a new company which was established in 2000, and specializes in the design and construction of public works projects such as bridges, tunnels, and parking facilities. We had worked on relatively small business for two years. Now our company, along with others, has been asked to build a bridge for Aizu-Wakamatsu City. The bridge connecting Aizu-Wakamatsu and Kitaaizu-mura will upgrade transportation infrastructure. Our department manager has just assigned us to work on a bridge-building project, so we decided to draw up the plan as a project team.
The main problem is that there are many competitors. Being lots of building instructions is another problem. So it will be important to construct the bridge as cheap as possible and to think about strength and beauty naturally. As an experiment, we decided to construct a paper bridge which suits following specifications, and then, we will think about it if it seems good. In this case, an actual length of 100 meters is 1 cm on paper's bridge. Minimum span from end to end is 18 cm; Minimum clear roadbed width is 6 cm; and minimum clearance under bridge is 4 cm. For safety, protective guardrail walls at least 1 cm high are required on the sides of the roadbed. The bridge must be securely anchored to the base on which it is to be built.
We must create the bridge safely, srtongly, and cheaply. If we regard safety as the most important prospect, that means that the bridge must have the guardial walls and some posts; moreover, we must build the entrance angle of the bridge gentler. That costs us much money. On the other hand, if we reverse the order of priority, we can get a cost reduction, but the bridge will be very dangerous. Aside from this, the charge of the same size area changes where we use. If we don't consider how to cut the sheet, the bridge will cost excessive money.
The bridge that we are planning has 18 cm-long span, 6 cm-long clear roadbed width, and 4 cm-high clearance under itself. We determined that the bridge need not be larger than required on the specifications because there's no use expanding. The bridge also has two 1.5 cm-high protective guardrail walls on the both sides of the roadbed. The bridge also has two 9 cm-long ramps on each side. We think that the length 9 cm-long is enough for the bridge because it seems not so steep. If we make it gentler, it costs us about 2,000,000 yen or more; and on the other hand, if we make it steeper, it seems too steep. For safety, protective guardrail walls should be on the sides of the ramps so as not to fall from there. We decided to put 4 pillars on the each corner of the roadbed to reinforce the bridge. Each pillar is rolled up to a column. Finally, we put decorations to the bridge to connect the guardrail walls of the roadbed and the ramps. Thus, our bridge needs 126 square-cm of papers as the materials for itself, that cost us 17,000,000 yen (figure #1).
The following table and graph show if the ramps are easy to climb, the roadbed is safe, and the bridge is stable against typhoon. That includes the results of test for the other companys' bridges.
The result of safety and stability test
| Company | Cost | Ramps | Safety Test | Typhoon Test |
| Akiyama-Kensetsu | 2,410,000,000 | A Little Too Steep | Not Bad | Strong |
| Show Hey | 3,650,000,000 | Good | Dangerous | Strong |
| 3.I corporation | 4,990,000,000 | Good | Good | Strong |
| I^3 STC | 2,620,000,000 | Too Steep | Dangerous | Wobbly |
| Ogura-gumi | 1,200,000,000 | Too Steep | Good | Shaking A Little |
| Muneo | 4,030,000,000 | Too Steep | Not Bad | Shaking |
| Team Abe | 1,840,000,000 | Too Flexible | collapsed | Flattened |
| MHMA | 2,070,000,000 | Too Flexible | Collapsed Low Overhead Clearance |
Dancing |
According to the result of test, our bridge's ramps are a little steep, and the bridge is somewhat weak. We decided to lengthen the roads of ramp to make it gentler and add two pillars under the middle of the roadbed.
If the roads are lengthened, ramps become gentle and it becomes easy to pass along a car. By adding pillars, the weight to one pillar is mitigated and the bridge become stabilized.