Post #479: How many people could you house at the Giant Food property, if you really tried?

Posted on December 5, 2019

(Click this link to download a spreadsheet with all the VDOT traffic counts for the Town of Vienna:  VDOT traffic counts 9-27-2019)

This is a little thought experiment, prompted by Town Staff’s continuing to push the idea of six-story buildings under MAC.  Rather than fight that, I figure, what the heck, let’s just run with it.  What would we get?

Best guess?  A six-story MAC development on the Giant Food property would yield about 1400 new residents, or roughly an 8.5 percent increase in the population of the Town of Vienna.  All in one place.  And maybe a 15 percent increase in peak rush hour traffic on Maple?

Such is the power of medium-density housing.

Detail follows.

Four … no, Five … no, Six Story Limit.

The idea of raising the MAC height limit to accommodate five/six-story construction came up, out of the blue, at a Town Council work session on 10/9/2019 (Post #413).  That was raised by the Director of Planning and Zoning, and was pretty clearly and thoroughly shot down at that time, as you can read in that posting.

And yet, it’s ba-ack.  As the staff drafted up its proposed “Commercial Development” survey, there was the six-story building again.  So this appears to be something that Planning and Zoning is not going to let go of, despite some clear pushback from most of Town Council when it was initially discussed.

Fine.  Six stories.  First count the people.

OK, fair enough, they aren’t going to give up.  But for those of us who will have to live with it, let’s at least work out some rough numbers on what we might get.  Just a little back-of-the-envelope thought experiment.

The obvious place to put your basic six-story stumpie here in Vienna would be the Giant Food property.  Which, as you probably know, got sold last in May 2018 to an investment LLC, at about twice the (then) tax valuation.  (That used to be all hush-hush, and Town Council members weren’t supposed to use the G-word in public, but now we’re all allowed to talk about it openly.)

I have refreshed a prior estimate of new Vienna residents per acre under 4-story MAC construction.  My best guess is that these buildings are coming in at around 84 new residents per acre, on average.

But that is for three floors of housing, while a six-story MAC building would allow five floors of housing.   You have to multiply by 5/3 to get a projection for six-story construction.  Accordingly, the ten-acre Giant Food site, if built at current MAC population density per floor, but with a six-floor limit, would yield (10 x 84 x (5/3) = ) 1400 new residents, or about an 8.5% increase in the population of the Town of Vienna.

Now count the cars.

Now add a crude estimate of potential impact on traffic.  Let’s say half those people drive to work in the morning, and they leave at a steady rate over a conventional two-hour “rush hour” period.  That would then add 350 cars to the peak AM hour on Maple.  (That’s 700 workers out of 1400 residents, then divided over two hours.)  VDOT’s numbers currently show just under 2400 cars/hour during the peak hour on that segment of Maple now (those are at the top of this posting).  Rounded, those 350 additional cars would increase the peak hour traffic by 15%.

You can quibble all you want with my estimates. I’m not presenting this as anything other than a simple back-of-the-envelope exercise.  But I think it’s enough to show that these decisions are going to matter materially to those of us who live here. 

Fool’s paradise

And to bring it all home, couple Vienna’s new drive for “economic development” along Maple, and recasting Maple Avenue zoning as “commercial development”, with what appears to be a steadfast refusal to consider adding more traffic lanes to Maple (Post #464).

To believe that this combination of policies will work out well is to live in a fools paradise.   That is, to believe we can have a major expansion of the residential and commercial use of Maple Avenue, without expanding Maple Avenue itself.  It’s not exactly rocket science to ask “where are all those additional cars going to go”.

You can have significant development and construct gigantic roads to handle the traffic, as with Tysons.  That makes sense, and it works.  You can take a small road that is at capacity, and leave it alone, as was formerly the case with Vienna.  That kind-of makes sense, and kind-of works.  But you can’t have a big push for development, on a small road that is at capacity.  That doesn’t make sense, and it’s not likely to work well.  At least, it’s not likely to work well for current Vienna residents.

So I guess my contention is that if Town staff are going to be pushing ever-denser development, then they need to show us their plans for widening Maple Avenue.  Because no matter how I cut it, that’s the only way this whole thing makes any logical sense.  Alternatively, if they are too chicken to do that, then maybe they need to back off this push for ever-denser development along Maple.  At least until some saner heads have sorted all of that out, and can present some coherent plan that makes sense, and might work.