At the end of a skewed bridge, how is tha transition from bridge ties to ballast ties handled?
Since one longitudinal beam is longer than the other, do some ties rest on the bridge beam at one end and ballast at the other?
I have seen this handled two different ways, depending on the angle of the abutment to the centerline of the track.
If the angle was only a few degrees, the last bridge tie would be skewed at the very end of the bridge girders. The adjacent 'landside' tie would also be skewed, and only a few inches removed. This was only true if the angle wouldn't cause the skewed ties to touch the adjacent straight ties.
More usually, the bridge ties would be carried into the ballast, one end on gravel, one end on steel. The first standard tie would be the first one completely supported by ballast. Tie spacing would be normal for each type.
Chuck (Modeling Central Japan in September, 1964 - to AAR/ASCE standards)
Hello all,
In the book "The Model Railroader's Guide To Bridges, Trestles & Tunnels"; Jeff Wilson, 2005 Kalembach Publishing Co., there are several references to your question on skewed bridges and abutment interface.
Unfortunately, from this publication, there seems to be no standard answer.
On page 26; photo 4-2, shows a skewed bridge where the ties begin perpendicular to the tracks and then in, what could be best described as a fan pattern, the ties end parallel to the end of the skewed bridge.
Then, on page 45, there is a section on Skewed Spans which shows several photos of skewed bridges.
In the section on page 45 it shows two photos of skewed bridges with the following text:
"The panel joints in a skewed truss bridge still must be directly across from each other; the two sides of the bridge can't just be shifted off-line by a couple of feet. Because of this, the skew in a truss bridge will be off by one ore more panel lengths. Subdivided bridges are often used for skew spans, and bridges may be skewed on one or both ends."
My takeaway from this is that as long as the skewed ends of the bridge spans rest on a solid abutment with fixed or movable pedestals (shoes) then it is up to the individual railroad as to which method best suits the particular situation.
Note: The fan patterned ties were on a closed deck bridge with the ballast continuously running from the roadbed to the bridge.
The ties on the open deck bridge ran perpendicular to the rails from the abutment all the way across the span. The ballast ended where the skewed abutment met the open deck of the span.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"