Here is another bridge I built a while ago. It’s been used quite a few times on M>ltc layouts, and I decided it was time for it to retire.
It’s quite a simple one, and really follows on from my last Cable Stayed Bridge, using similar techniques, but with a much different result. The most interesting attribute is that it is mounted directly on the floor, removing the need for any lowered table.
The main support is a hollow 4×4 stud tower, encasing a 2×2 stud technic rod. At appropriate places along the length, technic pins attach to 1×1 technic bricks, which are held in the outer casing. Because LEGO is not 100% perfect, this actually results in the technic rod being under tension, and thus makes the tower very strong while allowing it to flex, similar to pre-stressed concrete.
The deck sections are basically the same as the previous version, except the cable attachment points were moved to the centre. The deck does flex quite noticeably when trains cross, but there hasn’t been any failure.