12-01-2018, 09:43 PM
(12-01-2018, 08:23 PM)jamincan Wrote: I forget if it was ever explained, but does anyone know why they raised the tracks so high on the Northfield bridge? It seems it would add a lot of extra weight on the bridge, and I can't think of what the benefit would be.
They made a decision to use ballasted track instead of replaceable ballast-less track (like they use at the two double crossovers) with expansion joints to reduce long-term maintenance costs as the ballasted track would be more flexible as the temperature changes. It's heavier than ballast-less track but easier to correct deficiencies that will happen over time by just running a tamper over it whereas the expansion joints will wear on ballast-less track resulting in a need for more frequent rail replacement (not to mention the ride over the bridge will be smoother).