I spent some nights on this seemingly impossible level, until I found out that "deck" is much stronger than crossbeams, both in compression and suspension. So I switched to "complex" and built an arch made of deck below the railroad deck. looks funny, but works. Still, it needs some try and error, but finaly you´ll make it!
Could somebody please give me a hint on how to solve Hard Level 6? This whole just using iron thing is getting to me, and i think i may be getting a little to complicated with my design.
I also build under the brigde
First made a high arc then began to make a not so high arc untill the money ran out (roughly 2 sections on each side)
Also, some ideas on Hard 6 can be found
here.
I put iron on the underside of the bridge with sorta a truss design until i got to the last 2 parts near the middle then i built it on top of the thing.. it's kinda funky but it works.. I wish i could help more with a picture or something.. but i lost my unternet websites ;(