Roundabouts revisited

I have already written some thoughts about roundabouts around five years ago, but I think it would be good to revisit this again. Especially with the pending proposal to establish one at the Cebu South Coastal Road (CSCR) at the South Road Properties (SRP) at the junction of F. Vestil Street. A roundabout, which we commonly call a “Rotunda” is a kind of intersection where two or more roads meet in several directions causing a need to “manage” which passes through first in the “common” road space.

Ordinarily, when two roads cross each other, there are 12 possible different movements or directions. The vehicles coming from four different directions can turn right, left, or go straight through. It’s more complicated when there are more than four roads meeting, but ideally, the management of flow is either done manually by an enforcer at the middle, or a traffic signal light, either at fixed time intervals or managed by an automatic traffic detection system. A roundabout allows all traffic to flow continuously.

Roundabouts can be explained in transportation science, including their capacities, and pros and cons, but we can also simply learn about them from existing ones. Luckily, we have a good example at Fuente Osmeña. For those who’ve been to Metro Manila, there’s a bigger one at the Quezon City Elliptical Circle. The one planned at the CSCR won’t be as big, but the general traffic flow may be analyzed in the same way. Anyway, the questions to be asked are only, “would it work?” or maybe, “would it be better than a signalized one?”

This is where transportation science, which most people usually refer to, comes into play, together with economic analysis, of course. Intersections, especially the signalized ones, work sufficiently and so do roundabouts as we can experience every day in Fuente. Size does matter, which is why we have been experimenting in the past with installing and removing one at Osmeña Boulevard-N. Bacalso/P. del Rosario junction. Eventually, we settled for signalization, which can be a lesson, or two, learned --roundabouts may not work well with simple junctions, and it needs space!

The latter reason is important --roundabouts need space, and the bigger (wider) the roads that go into them, the more traffic they are supposed to manage, the bigger they have to be. Quezon Circle is 500 meters in diameter (the center circle) while Fuente is 120m. The one proposed at the SRP would probably require only 40 meters but can be bigger if desired. The only problem is the CSCR is a high-speed expressway which is supposedly non-stop. That’s the very reason the government spent millions of pesos for the U-turn slots at the end.

At any rate, prudence dictates an economic study/analysis should be done first before proceeding. There are always advantages and disadvantages in any new proposal, but the government must always adhere to the need for viability, one that is not project-specific but considering the wider economic feasibility. We must always remember that any economic advantage this may bring must offset/be greater than the figure we lose of the economic benefits gained from the two U-turn slots at both ends of the SRP.