Wednesday, June 28, 2006

Why eliminate the underpass?

The two main reasons given in the various planning studies for eliminating the South Capitol Street Underpass at M Street are:

making the area more pedestrian friendly
providing a more dignified setting for St. Vincent De Paul Church

More pedestrian friendly?

Eliminating the underpass would increase vehicular-pedestrian conflict at M Street, as well as the streets to the south, where the median barrier would also be eliminated to allow pedestrians to cross at N Street.

South Capitol Street would become more pedestrian friendly insofar that pedestrians could cross at N Street (from existing residential neighborhoods to the stadium).

But since N Street is right between the South Capitol Street Underpass and the South Capitol Street Bridge, it’s a place where vehicular traffic is more likely to go faster, and hence undesirable for a pedestrian crossing. Indeed N Street is right where this viaduct – basically the land portion of the South Capitol Street Bridge that actually runs along the South Capitol axis touches down.

That is, until that segment of vehicular viaduct, is torn down, as was planned to happen in about 2014 after the replacement bridge was built alongside to the south. However, the supplemental $47-118 million interim plan would accelerate this viaduct segment’s demolition to 2006.

In light of their close proximity, one must run through the different possibilities for this underpass and this viaduct. Eliminating the viaduct first, or at least building a northbound ramp to 1st Street SE would better disperse traffic. Eliminating the underpass would serve as a bottleneck, and would be less needed to make the area to the south more pedestrian friendly by shortening the viaduct, which would allow an at grade intersection at O Street.

A more dignified setting for St. Vincent DePaul Church?

Eliminating the underpass eliminates the depressed approaches that representatives of St. Vincent DePaul Church from the Washington Archdiocese seem to find objectionable.

But eliminating the underpass is not required to address the underpass/viaduct proximity issues, nor is it required for eliminating the depressed approaches.

With officials stating their objectives as making South Capitol Street more pedestrian friendly, and with Catholic Church officials apparently objecting to the depressed approaches (at least the one to the north of M Street in front of the St. Vincent DePaul Church), a logical alternative would be to retain the underpass in a different form that eliminates the depressed approaches at and near St. Vincent DePaul Church via including its excavation as part of a longer cut and cover tunnel.

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