Adding rubber or carbon fiber would do little except $$$$.
Rail weight is account depth of section, it needs to be stiff, and depth of section is the way to get it.
This was all thoroughly beat on over a hundred years ago, and a lot of the work was done by Dudley of the NYC&HR. I think it was he, along with wife, who lived in a PV that was set up to record track geometry at speed.
That was prompted by high passenger train speeds
Then cars and locomotives got very large and a crisis developed with the steelmaking. After lots of failure the problem - or one of them, was determined to be the position of the steel in the ingot- cooling caused separation etc in the upper part, so specs were revised to include WHICH part of the ingot would be accepted for rolling. Rail shape also was heavily investigated. Harriman Lines among others made records of breakage and found some sections were more prone to failure. Everybody had a profile - the steel companies, ARA, AREA, ASCE and individuals.
Somebody tell us about the "Headfree" section that SP was found of in the 50s[?]
Rail research continues, trying alloys, heat treat, grinding to restore profile of the running surface. UP did a recent study on Tehachapi as to the effects of track geometry on wear- cant and superelevation changes made great differences in wear on curves, and UP has pretty much perfected a computer model that corresponds to the real world to correlate speed, weights,and curvature with alignment tweaks
factoid-About 1931 PRR started using 152 lb rail for their heaviest mineral traffic.
The concrete tie has been extensively researched in the last 50-60 years as well. Problems include shape to provide maximum strength in the right places and maximum track support with fewest number of pieces. And all that makes manufacture more difficult as well.
Another facet of rail design/wheel load is the local effect of high bearing stresses under the wheel- that leads to 'shelly' rail, where flakes of the head are squeezed off.
IIRC the original design of the Black Mesa and Lake Powell was based on high capacity gons, and rapid rail destruction prompted a reduction in load per car, and the addition of a third trainset to maintain daily capacity. Powder River coal gons have larger diameter [ over 33 inch] wheels to reduce rail shelling with higher car loads.
Gonmavens can tell us what wheel sizes 38-40-42??
Articulated wells also utilize larger diameter wheels for the interior trucks but outer trucks have 33 inch- obviously [?] this is not a 'rule' - but take a close look next time you are behind the yellow line.