Traditional O-gaugers might be interested to see that pressed-steel crossties ("sleepers") were used on some railways in other countries. The photos show examples on standard gauge tracks in NSW Australia in 2008. These are secondary tracks, not currently mainline tracks. I suspect the steel sleepers are not as suitable or cost effective for modern heavy traffic with higher axle loads. [edit: new designs of steel crossties have advantages for many modern applications]
The first photo shows old style pressed steel crossties in the siding track at right, next to an active main line. They have a boxy rectangular shape.
The second photo shows a steel sleeper with more rounded contours and Pandrol tie clips, in former mainline track near Thirlmere which sees occasional traffic to the state rail museum.
In the third photo, on a currently disused line south of Thirlmere, a steel sleeper is stamped "Colville Ltd 1952". This was former mainline track, bypassed by a better alignment.
Steel ties were used in areas where suitable timber supplies were distant, and/or where materials were vulnerable to deterioration from humid climate and termites. In some places old rails were commonly used for telephone poles along the tracks, for the same reasons.
I remember seeing steel ties on the long-since-defunct 42"-gauge North Australia Railway near Darwin in 1970, but I don't have photos of that.
