The flexibility and lower cost of buses is actually a profound disadvantage from an economic signalling perspective. I'd argue the most important reason why tr

The flexibility and lower cost of buses is actually a profound disadvantage from an economic signalling perspective. I'd argue the most important reason why tram or rail line is better than a bus is the sunk cost of installation, which prevents rerouting and discourages withdrawal of service. This encourages private investment along the service corridor because the route is not subject to political whims. In other words, it can be relied upon for time scales on the order of decades, and that matters in real estate. (Also they're generally much more pleasant to ride than buses, but I don't want to overemphasize aesthetics. The real reason people prefer trains over buses is reliability.)