This is a
Walkthrough, a
Game Guide and also has nice
Game Tips. The solutions I'm about to share with you are based on real engineering knowledge I have researched online (and the basic knowledge I have from 1 year of architecture studies). Theoretical models are presented and then stripped down to the most minimalistic designs to achieve optimal levels of cost VS stress resistance. I trust these tips will be very useful and eye-opening.
Play the game here
LEVELS 1 - 6
First of all, check out
http://www.matsuo-bridge.co.jp/english/bridges/index.shtm to have the same theoric background. We will be using the Girder, Truss, Rigid Frame or "rahmen", and the Arc. Cable Stayed and Suspension bridges can't be built yet in these levels.
Level 1 (tutorial) & the Double Lever design
This is the most simple bridge design there can be for gaps requiring more than 1 segment. You'll be surprised how useful this design will be during the whole game. The particular bridge on the image covered the 6.3m gap with a cost of $124.
I call this the "double lever" bridge because it uses 2 anchor points, each as a lever point for one of the two walking segments. Both segments or levers are fixed to each other at the center of the gap.
Tip: to find the center of the gap precisely, note the distance (e.g. "6.8m") annotation in the blueprint; it is located exactly at the middle of the space to bridge.
The inclination of each segment is the most important factor to consider, the steeper you can make it, the more stable it will be. But there is only so much the cargo folks can do and they will get stuck if the bridge is too steep.
Tip: to achieve greater inclinations, avoid close angles. Instead use various segments, each one steeper than the previous one.
Level 2, the Girder and the Truss designs
To cover the first 7.6 metes we could use a girder bridge:
Here we have 2 versions of the "Girder" bridge. The first one is a straight girder supported by a minimalistic web (see
Matsuo girder page). The second one is an more economical version of the same design.
Tip: try to reduce the amount of material you are using to seize every cent of budget. but note: using more segments, even if it looks like less material, is always more expensive due to an initial fixed cost on each one.
The first bridge costed $257 and the economical version $236. Notice how the eco. version uses a larger central segment.
Tip: central segments, and then right ones, have priority for length (in simple designs). Note that the largest a wooden beam can be is about 4m.
For the second space of 6.8m, the anchor points would naturally imply something like this:
This design is a "Truss". It is based on a wall of triangles. The upper and lateral (outer) segments give support for tension as the center segments and the walking part in itself support the compressive forces of the bridge and of the cargo moving on them. This specific design costed $543: a bit expensive.
Tip: don't assume that you have to use every anchor point just because it exists on the blueprint.
A more optimal design ignores 2 of the anchor points to construct a smaller truss:
Note that the support wall may be placed on or under the walking bridge. This particular design costed only $261.
Sadly enough, neither girders or trusses are the best options in this level. 2 double levers is all you need to pass it:
But remember to make the bridges as steep as you can, otherwise the wood won't stand the compression when the worker is coming back with the cargo.
Level 3. Rolling down hill with some heavy duty
The main problem for this bridge is to support a heavy load (the rolling elephant) coming back towards the left. Its weight is heavy enough as it is, but its made even worst by gravity as it rolls down.
Given the anchor points we can use a proper girder bridge (with a full beam web for extra support) like this:
Notice how the curve of the bridge is more pronouncedat the left extreme? This convexity allows the direction of the cargo movement to flow easily without applying its full weight onto the structure. The elephant and worker keep gaining kinetic energy (and speed) that is finally released on steady land. If the elephant were to be pushed towards the right, the bridge would probably yield. This girder covers 7.2 meters and around 2m height with $475 bucks.
Tip: always reinforce more the left extreme of the bridge in the game. The cargo moves towards this direction. Combine this with a convex curve when possible if the cargo comes from a greater height.
In this level I also get a chance to use my patented
spider-web design:
This solution is actually just an intuitive construction following the convexity principle mentioned previously. I call it "spider web" because it deals mainly with tension forces (as do suspension bridges), like a common aracnid silk trap. Web solution: $419.
But again, the optimal solution is much simpler. Although you can join both extremes with only 2 segments, this time no inclination is enough for a double lever. But a combination of that (convex double lever) and a minimalistic girder web on one side will be enough. We use the right side because that's where the ancor point is. The left side won't need mush support as the weight won't actually sit on it but simply pass rolling down:
I call this the "triple lever" just to baptize it somehow. It costed a minimal $209 game moneys.
Level 4 & the Arch bridges
This is an arch design. Formed with 4 long beams, it has a base support below and a crown above. It supports the 4 walking segments in their mid intersection with a wooden "cable". It covers 8.9m with $471. This simplistic solution intends to correspond to Illustration #3 in the
Matsuo arch page. The second image shows a sort of arch built completely under the girder part of the bridge (Matsuo Illustrations #1 and #2). This bridge was $432.
My most minimal, yet complete arch is really a double lever supported by short (thus strong) extended land extremes:
The arc here is a formed from both the wood walks and connectors. Its expense? $318!
An even less expensive bridge is the weird left-extended double lever or simple X D-lever (shown in the second image). It costed only $254 but I had to try more than once to build the definitive bridge that wouldn't break down.
For the second, 9.3 gap, we have this natural solution:
Which only costed $321. Its an eco. girder. Notice that it has slightly less inclination on the right side, so that the cargo -which carries inertia from the right down-slope- moves smoothly towards the center segment without breaking the first joint.
Or... You can use another X D-lever bridge to spend only $246 (depicted on the right). Beware, it might break if not steep enough.
OK from here on we can head straight to the point and not waste more time on explaining theoretical models that aren't optimal!
Levels 5 and 6: the Rahmen
First thing 's first: Lets bridge over the initial 5.1 meters with this combinatorial design:
This is a tricky $255 bridge. It looks like an eco. girder, except it lacks the central segment. The main concern is its central anchor point, as it is the only thing that holds the thing together. It also resembles a spider-web, and as such, dealing with tension is our principal goal. Try too keep the upper walk segments as short as possible to minimize tension.
Now, for the main gap here, we will go with the anchor points and use a
Matsuo Pi shaped Rigid Frame (Illustration #2) or "rahmen" bridge. It will easily cover over 8m in length and approximately 2 in height with five segments:
$302 is all you need to realize this model. Perhaps the closest to theory that actually is optimal in the game. It even holds almost still, like a rigid frame.
This is the first level with 3 bridges to build. The last one (right) will look like the best one on level 3, only mirrored.
We will do another rahmen for level 6, ignoring the left-most anchor point (Don't forget to bridge the second gap):
The rahmen should cost a bit more than $300, covering 12.1 meters in length according to the blueprint, and approx. 1m in height. This structure looks a bit less rigid than the one in level 5, for we needed to make it more curve in order for the segments to reach each other.
This Game Guide continues here:
http://rehalcon.blogspot.com/2009/05/cargo-bridge-game-tips-for-optimality.html.
PLEASE LEAVE YOUR COMMENTS!
For additional reference you can check out these videos of levels up to 24:
http://eternalgamelist.com/blog/game-walkthrough/cargo-bridge-game-walkthrough-videos but I must tell you these solutions are not nearly optimal.
