Made a little video of the first run over the new bridge and tunnel. Inner loop will probably get done in the spring, after a new waterfall pond is made on top of the tunnel. Song is by Lonesome Spurs.
Thanks guys. It's a McKeen motor car that I made from scratch. No one makes a model of it. You can see some build pix on my web page of it's trailer, same way I made it. Had an article in GR about making it. August 1997 issue. Got onto McKeen cars in a book by a Nebraskan, Francis Gschwiend, he wrote the 'Kearney and Black Hills' RR book. McKeen cars were first used there. Do a search on Google, pretty interesting. The one that was left has just been restored in Arizona, or Nevada, don't recall which. My model has a Aristo FA-1 motor block, body shell is plastic, heated in the oven and bent over a wood form. Same way I made my streamliner cars, check my web site.
Thanks Mike. The bridge replaced a old trestle. I needed a bridge for two tracks, had two trestles over on the other side, didn't want to do that again. Loved the bridges that Marty has, so went with a welded bridge. Only sags abut 1/8" across the 14', still mulling over putting a support in the middle. Might have my welding guy weld up a brace of some sort.
Please don't spoil the effect of a very nice, very impressive bridge by adding a pier at or near the center of the span as additional support. All spans experience some sag. Mark's Mechanical Engineers' Handbook has calculations for the sag induced by mass of any beam. Without specifically referring to the formulae that are included, it is my suspicion that the center sag that you have noted is a natural effect and will not result in the eventual failure of the span.
The only concern that I have is the bridge constructed of material with sufficient mass and structural strength to support the maximum intended load for the span. Place a mass at the center of the span equivalent to the maximum load the span would experience and determine the deflection caused by this load. If it is no greater than the natural sag of the beam supported at two ends then you have no concern. You would not require a center support pier to avoid collapse under maximum beam load.
Your effort is most impressive in its location and deserves to be maintained for its sheer impact on viewing.
Heaviest thing it will carry will be the Aristo Live Steam Mikado and some cars, so about 40-50 lbs I imagine. Heck it weighs more than that. I've pushed down pretty hard in the middle and there is no deflection. If I put a center support in, it will be strictly for esthetics, if I feel I need it.
forgot about the winter storm going through your part of the country. We had 65 degrees yesterday, only getting up to 55 today. However, I know Michigan's mother nature is going to make us pay for this unseasonable warm weather. So, I steam when I get the chance. Keep warm and do those "winter projects".