I think your intention is good - and I agree we should put in modern fiber. But only a small percentage of fiber put on long routes uses single wavelengths. M

I think your intention is good - and I agree we should put in modern fiber. But only a small percentage of fiber put on long routes uses single wavelengths. Most fiber going more than 5-10km uses DWDM and that is indeed an important place to put in modern fiber. However, most of the railway routes in 1998 used fiber that supported 32*40G lambdas, so the problem with most of the fiber laid over the last 20 years is not that it can't handle more than 1gbps. Most of the problem is the equipment, not the type of fiber used.