Post #371: Library Park, Part 2

Posted on September 4, 2019

This post is a followup to my prior writeups of the new Patrick Henry library.  You can see my discussion of what the consulting firm proposed in Post #367, and you can see my “Library Park” alternative in Post #369.

The point here is to ask the following:  Sure, it costs more to put the parking garage underground, as in my “Library Park” proposal.  But in return, that buys the Town a one-third-acre park on Maple Avenue.  Is the tradeoff worth it?  And I mean that in a very narrow sense: Is this cheaper than simply buying a third of an acre of commercial land on Maple, given current prices?

The answer appears to be yes.  In round numbers, a $1M investment in putting the bulk of the parking underground would buy the Town a new one-third-acre park on Maple Avenue.  That works out to about $3M/acre.  As I understand it, commercial property on Maple is currently going for around $6M/acre.  So, think of this as a way to get park land at half-price.  (It’s actually slightly less than half-price, due to the foregone tax revenues that would result from buying commercial land outright and converting it to park land.)

To be clear, there’s no sleight-of-hand here.  This is just a consequence of what builders already know:  When land prices are high, it’s smarter to conserve land by build parking garages than to have surface parking lots.  In this case, I’m just using the land that would be saved by an underground parking garage as a park, instead of using it to make a larger building.

This approach has several other advantages beyond being a (comparatively) cheap source of park land.  The foremost of those is that this frees Fairfax County to build a showpiece of a library, instead of stuffing the new library under a parking garage.

I hope the Town will give this, or something like this (underground parking) all due consideration.

Cost of parking, alone

The main drawback of my “Library Park” proposal is that underground parking garages cost more than above-ground parking garages.  (I have no idea why, but there is general agreement that they do).  So putting the parking underground is costly.  The first question to ask then is “how much more costly is it”.

To answer that, I’m going to present a few ballpark numbers the cost of construction for parking places.

First, though, I need to modify the Town’s Option B1 so that B1 and my “Library Park” proposal are on a level playing field.  The B1 option provides about 30 more parking places than my “Library Park” option does.  In order to cost these out, I’m just going to drop those 30 additional garage parking places out of the B1 option.

For cost per garage parking place (above-ground versus below-ground), I am relying on this source (.pdf), inflated to 2019 using a US construction cost index from this source (.pdf).  For cost per surface parking place, I took a guess at $5000 per space, based solely on the round number that appeared most often when I did a quick internet search.

When plug in the numbers, on net, it would cost about $1M more to build the 175 parking places in the “Library Park” proposal than in the modified “B1” proposal.

The upshot is that it would cost about $1M more, to construct the parking.  But this would result in a one-third-acre park.  In effect, this would allow you to create park land on Maple for $3M per acre.

What would it cost to buy land on Maple and convert it to a park?

That’s what the Town did to create the Town Green.  There used to be a little commercial establishment there, with a bar in the basement.  The Town bought it, tore it down, and created much of what we now know as the Town Green.

What would it cost to do that today?  My best guess, based on looking at a variety of lots, is that you can buy commercial property on Maple for somewhere around $6M/acre.  That’s from looking at a variety of lots, but the easiest benchmark is the May 2018 sale of the 10-acre Giant Food property for $63M.

If that’s true, then at first blush, the “Library Park” option creates park land on Maple for about half the cost of purchasing existing commercially-zoned land outright.

There is a little more to this story, but the current land price dominates the calculation.  (What else matters?  Whenever the Town buys commercial land and converts it to public use, it then loses the future stream of tax revenues that such land would generate.  That’s property tax, BPOL (business license tax), and in some cases sales/meals tax revenue as well.  Because the Town pays such low interest rates, the “net present value” or “present discounted value” of those lost taxes may be material.  But taking the Giant Food lot as a convenient example, based on Fairfax County tax records, that property yields about $10,000 per acre in Town of Vienna property taxes.  Currently, the Town pays about 2.2%/year on its bonds.   The net present value of the next 30 years of property taxes (alone, no BPOL or sales tax) is under a quarter-million dollars.)


Admittedly, this has been a pretty rough cut of the numbers all around.  And, the Town must do a needs assessment about this proposed new garage before it can make any sort of a rational decision.  (Or, in English, estimate the number of parking spaces it needs.)  But here’s my conclusion, for what it’s worth.

Every commercial enterprise submitting a MAC mixed-use proposal has seen the value of creating underground parking.  They used that to maximize the size of the building they could put on the lot.

Here, I don’t think the basic logic of underground parking changes just because this is a public enterprise, and our goal is not to build the biggest possible building.  The basic logic is the same:  underground parking conserves land.

My contention is that by putting the bulk of the parking underground, at a cost of perhaps $1M more than the current option B1, Town would get several benefits.  These are:

  • A new one-third acre park on Maple.
  • A stand-alone “architectural showpiece” of a library (instead of a library located under a parking garage).
  • A Town that centers around a beautiful library and park, instead of a large above-ground parking garage.

That said, if the Town decides it needs hundreds of parking places, at that one location, then the Library Park option would appear to be off the table.   What we need next (or, really, should have done first) is some reasoned, data-based assessment of how many parking places the Town of Vienna actually needs at that location.