Pedestrian Observations - Mass Transit on Orbital Boulevards

Quotes from Alan Levy on deciding between tram or metro for ring roads around cities, in this case specifically the Bundesstraße 4 R in Nuremberg.

In favor of light rail, there’s the issue of speed. Normally, the advantage of subways over tramways is that they’re faster. However, on a circumferential route, the importance of speed is reduced, since people are likely to only travel a relatively short arc, connecting between different radials or from a radial to an off-radial destination. What are more important than speed on such a route are easy transfers and high frequency.

In favor of metro, there is the cost issue. The same factors that make speed less important and frequency more important also make it easier to build a metro. If the road is wide enough, which I think the one in Nuremberg is, then cut-and-cover is more feasible, reducing costs.

As usual with the blog there's great comparisons drawn from other cities like Paris and Cologne and other points made on trading capacity for frequency.