The picture above shows why Edinburgh track laying was perhaps so time-consuming, as there was a thick concrete base laid, then
tied sleepers placed on that, and this was then all encased in more concrete. Life expectancy will not allow us to see how worn track will be
replaced, but meantime Siberian iron-ore trains could probably be supported along Princes Street. This installation method also required all the services ( in unknown positions) to be moved. This is not necessary with some other track systems.
Alternatives to the heavy rail approach adopted in Edinburgh: