Friday, August 17, 2012

The Overwhelming Over-Infrastructure of South Dallas

Since I went to this effort, I thought I'd post it.



I've been discussing the proposed SM Wright Freeway to Boulevard with some interested advocates around the city.  There is significant debate between the community who want a 4-lane road and TxDOT and various political leaders who want 6-lanes, because...well, of course they do.  TxDOT uses their utterly flawed and completely useless yet sacrosanct traffic modeling formulae to state that 6-lanes is necessary to move the projected capacity.  So I decided to look at how under capacity the areas arterial grid currently is.  The results follow in the informal email I'm about to quote verbatim:

"I just did a quick study of how under capacity the major parallel routes to 175 are.  First, if 175 (SM Wright) carries at its highest 78K vehicles per day, and a 4-lane boulevard could handle 31K, that leaves 47K we have to find a home for (nevermind the principle of induced demand and real world data suggesting up to 25% just disappears to other forms of transportation).  Adding up how far under capacity I-45, Lamar, RB Cullum, Malcolm X, 2nd Ave equals a shortage of 132,000 cars per day in relation to capacity or 281% more than we need (if we calculate the 25% of reduced demand, that's 374% more than we need).  In other words, you could say South Dallas is vastly "over-infrastructured" and there is plenty of room for the excess theoretical vehicles to find other routes.  

And I'm not counting all of the perpendicular routes like Grand, MLK, Pennsy, Metropolitan, Pine, or Hatcher.  Throw those into the mix and that's another 161,000 of empty capacity, 293,000 in total that the area's arterial grid is able to absorb."


So that puts us up net +258,000 vehicles per day, still not being utilized in South Dallas after we take SM Wright down to 4 lanes.  Of the map above (I forgot to show Pine), that's roughly 32 excess lanes more than we need. That means every single one of the eleven roads used in this study could afford to have two lanes removed (one in each direction).  Time to get dieting.

Disintegration = Disinvestment = the plite of South Dallas