Very thought provoking Ivan. In the UK before the railway bubble was the canal building bubble. Canals were seen as quicker way of transporting raw materials needed for the textile industry. Canals were built all over the country and help develop the infrastructure needed for the textile industry. Then railways came along and made canals redundant, Where I live a canal was built by private subscription. It was never used for commercial traffic as the canal bubble collapsed due to the emrgence of trains.
I fully agree that bubbles have both postive and negative roles.