3D (airspace) subdivisions

[dedkad]

I'm not talking condo maps, I'm talking an actual three dimensional subdivision, such as when one parcel takes up the ground floor of a building, a second parcel takes up the 2nd floor, etc.

My agency has processed a few, but we don't have any good subdivision regulations that address this. Have any of you processed a 3D map? Know of any good municipal codes that cover these type of subdivisions?

It's only a matter of time until somebody proposes taking four horizontal lots and doing a LLA to create a 4-story 3D subdivision. Do you think this would be exempt from the SMA under the LLA rules? What could be some of the problems that an agency might encounter if this is allowed without going through a typical subdivision review process?

[surveysays]

A condo plan is a 3D subdivision, it better be or it doesn’t exist.

[subman]

Below is a discussion on the matter. I can share example maps if anyone is interested:

A division of airspace or underground space is regulated by the Map Act. For the Map Act to apply to a particular development, it must fall under the definition of "subdivision" as provided in Gov C §66424. Under Gov C §66424, there must be a division of "any improved or unimproved land". Civil C § 659 defines "land" inpart as "free or occupied space for an indefinite distance upwards as well as downwards". Accordingly, adivision of airspace or underground space appears to constitute a division of land and therefore falls within the parameters of the Map Act.



Further the Map Act provides under Gov C §66411 that the"regulation and control of the design and improvement of subdivisions arevested in the legislative bodies of local agencies." This means that the City of Carson may apply its existing local ordinances pertaining to such and even create new ones to specifically address airspace and underground space subdivisions. The City ofLos Angeles has done this. Below are the relevant excerpts from the City of Los Angeles' Municipal Code.



SEC. 17.01. TRACT MAPS - GENERAL PROVISIONS.

(d) Subdivision of Air Space. The provisions of thisarticle shall apply to a division of the space above or below a lot with adefinite width, length, and upper and lower elevation occupied or to beoccupied by a use, group of buildings or portions thereof, and accessorybuildings or portions thereof, or accessory uses, (Air Space Lot, as defined inSection 12.03 of this Code). (Added by Ord. No. 156,681, Eff. 6/21/82.)



LOT - AIR SPACE. (Added by Ord. No. 156,681, Eff.6/21/82.) A division of the space above or below a lot as defined in thissection with a finite width, length, and upper and lower elevation occupied orto be occupied by a use, building or portion thereof, unit group of buildingsor portions thereof, and accessory buildings or portions thereof or accessoryuses. An air space lot shall be identified on a final map or a parcel maprecorded in the office of the County Recorder with a separate and distinct numberor letter. An air space lot shall have such access to a street (as defined inthis

section) or private street (as defined in Article 8 ofthis chapter) by means of one or more easements or other entitlements to use ina form satisfactory to the Advisory Agency and the City Engineer.

[subman]

OK, I couldn't pass this up. Attached is the vertical subdivision parcel map recorded to separate the old landfill (covered by a liner) and the development that will occur above it. This is the potential site of the NFL statdium in Carson, CA. Probably the most unique subdivision map I have been associated with in LA County. Related news article below.

http://www.latimes.com/local/california ... story.html

[Anthony Maffia]

What a nightmare that vertical separation is.

[Frank Romano PLS]

Is it just me, or does it strike anyone else as a little "over the top" (no pun intended) to claim a parcel to infinity, or the center of the earth? (see bottom of Sheet 13)

[Anthony Maffia]

That's the definition of land ownership, iirc. Excepting that you can't charge airplanes with trespass. What I don't like is the data dump of a terrain model, and the poor scan of the map makes it impossible to use OCR to convert the coordinates back into machine readable format. This map guarantees that the original surveying company is the only one THAT WILL EVER work on this site again.

A better way to map it would have been to decimate it into 5 foot or 10 foot grid and then for each grid square give the highest respective elevation. Or map giant polygons and give elevations at those points. Landfill closures I've seen are like 300' by 50' at a constant cross slope before a grade break.

Disclosure: I was taught how to do 3D tract maps by BKF San Jose based on Santana Row, and successfully filed one in the city of Dublin a year later.

[dedkad]

Great info, Dennis. Thank you.

But I'm still sweating the LLA. Based on the code sections and definitions you cited, it appears there is nothing preventing a subdivider from using the lot line adjustment process instead of the subdivision process to create four vertical lots out of four horizontal lots. Those configurations are two different animals when it comes to planning, zoning and building regulations. With our review of LLA's limited to just ensuring compliance with those regulations, we'd really have to tighten up our Municipal Code language to address the multitude of possible scenarios someone could come up with for airspace lot configurations. My brain hurts thinking about it, which is why I was hoping that some other agency had already laid the groundwork. Those regs from City of LA are pretty thin.