DC GIS Federal Reservation Data Capture Project

DC GIS Federal Reservation Data Capture Project

Bill Lescure

Geospatial Analyst

New Light Technologies, Inc.

April 24, 2012

Contents Background .................................................................................................................................................................1

Data Capture Process Overview .................................................................................................................................1

Figure 1 ...............................................................................................................................................................2

Researching the Source Documents ...........................................................................................................................2

The initial Data Sources ......................................................................................................................................2

Office of the Surveyor Document Management System ...................................................................................3

Figure 2 ...............................................................................................................................................................4

Secondary Data Sources .....................................................................................................................................5

Additional NPS Documentation ..........................................................................................................................6

DC GIS Data Sources ...........................................................................................................................................6

Figure 3 ...............................................................................................................................................................6

Source Research Summary and Example ...........................................................................................................6

Creation and Alignment of the New Line Work in the VPM ......................................................................................7

Figure 4 ...............................................................................................................................................................7

COGO Toolbar and the Advanced Editing Toolset ..............................................................................................8

Computed Vs. Recorded Values .........................................................................................................................8

Accounting For the Alignment of Neighboring Lots and City Blocks ..................................................................8

Figure 5 ...............................................................................................................................................................9

Benefits of the Project ................................................................................................................................................9

Related Links ...............................................................................................................................................................9

DC GIS Federal Reservation Data Capture Project Bill Lescure

New Light Technologies, Inc. Page 1

Background The purpose of this project was to research the exact dimensions of all of the federal reservations inside the

District of Columbia and capture that information in DC GISs Vector Property Map (VPM). The federal

reservations are pieces of land inside the District of Columbia that are owned by the federal government and

mostly controlled and maintained by the National Park Service. Until recently much of this federal property was

not well documented, or the documentation of the precise dimensions of the land was spread across a number

of source documents. In total, the Park Service owns approximately 6,776 acres of land inside the District. This

is a large amount of land to not have specific dimensions for. This project was important, in order to give the

NPS and the District Government an accurate and centralized inventory of the exact dimensions of this federal

land.

The Vector Property Map is a vector based geographic information system which contains nearly all of the

property information in the District. The VPM contains over 136,000 property polygons. Much of the property

bearing and dimension information in the VPM is very precise, and has been captured based on extensive

research of source documents housed in the District of Columbias Office of the Surveyor.

The creation of the VPM was a massive undertaking that took many years to produce. The DC GIS Program has

coordinated and supervised the VPM from its inception to its current state. The capture of the federal lands

within the VPM was the final, significant, uncaptured dataset within the VPM. In total, there are roughly 1150

different reservations, both active and inactive. New Light Technologies combined forces with DC GIS to

research and produce this federal reservation dataset.

Data Capture Process Overview To complete the work, a team was assembled that included a senior analyst to serve as project manager and

SDE administrator along with two GIS analysts responsible for data research, collection, and attribution. The

data was captured using ArcGIS 9.3s advanced editing toolset and COGO toolset, using a disconnected SDE

database architecture.

The senior analyst managed quality control, including checking the accuracy of the line work and attributes and

made final topological adjustments to layers that had coincident geometry with the newly created federal

reservation properties. Once the geometry for a reservation was complete, the finished line work was uploaded

to DC GISs Central SDE database within the Real Property dataset. This Real Property data is publically available

from DCGIS at http://data.dc.gov/.

The process for researching, collecting, and inputting disparate property line data was handled by the GIS

analysts and required attention to detail and consideration of a number of complex modeling factors . For

example, in some cases reservations are as small as street medians represented by a single polygon that stands

alone in the middle of a street right of way. Reservations can also share a complete boundary with one or a

number of existing lots or parcels. In other cases, reservations can stretch across many lots and blocks and

encompass a large area, such as Rock Creek Park which runs through the middle of Washington, DC.



Figure 1

The data capture process involved 3 main steps, the researching of all the source documents connected with the

reservation, the creation of the new line work using ESRIs COGO, editing and advanced editing toolsets and the

alignment of the new line work with the already existing line work inside the Vector Property Map database.

Researching the Source Documents The first step in the data collection process, was to look up the location of a reservation using a shapefile,

created by the District of Columbias Office of Planning. This shapefile contains all of the known reservations,

collected with approximate locations and without exact dimensions. After using this shapefile to zoom to the

location of the reservation, it was necessary to use a number of data sources to get a feel for the surrounding

area. The data sources that were used for this were the latest DC GIS orthophotos, the existing VPM property

lots in the area, the right of way scans, the NPS Map A, the NPS Reservation List and the Baist Books.

The initial Data Sources

The orthophotos and the existing VPM property polygons give a good overview of what is actually on the ground

in and around the reservation. After examining these two data sources, the next step was to look at the NPS

Map A. This is a raster map provided by the National Park Service, which contains the approximate location,

shape and size of all of the federal reservations in the District. This document has been scanned and

georeferenced by DC GIS. After looking at the NPS Map A, it was necessary to look at a list of all the federal

reservations, also provided by the National Park Service. This list often includes a square foot value for the

reservation, as well as a written description of where the reservation sits. Like the NPS Map A the list of

reservations is good for getting a general placement of the reservation, but nothing precise is provided, other

than the square foot value.

The right of way scans is a raster data source that is owned by the District of Columbias Department of

Transportation and has been scanned and georeferenced by DC GIS. The right of way scans are old and



damaged in some areas, but are rich with good information. The row scans provide detailed information on the

width of the right of way. The right of way scans break down the right of way into its component parts, the

roadway, the medians, the parking area and the sidewalk area. The data source often provides the exact width

of the right of way and all of its component parts. The right of way scans also contain hand written notes on

them, which often provide a book and page to indicate changes and transfers of land that have occurred.

The Baist Books are another good source of information to look at before collecting the reservation line work.

The Baist Books are not an official source of dimensional information, but can give you more specific information

about the placement of the reservation as well as information about the lots surrounding the reservation. The

original Baist Books can be found in the Office of Tax and Revenue, Real Property Service Center and in the

Districts Office of the Surveyor. The Baist Books have been scanned and georeferenced by DC GIS.

The Baist Books are map books that were created by a company named R. H. Baist from Philadelphia,

Pennsylvania. The company compiled street, alley and lot information for the real estate industry. It is likely that

these real estate maps were largely pieced together from sources at the Surveyors Office. The information,

while not official, is accurate enough to be useful. The four Baist Books that cover the entire city of Washington,

at the Surveyors Office were copyrighted in 1950, 1960, 1957 and 1967. Baist Book, Volume #1, was

copyrighted in 1957 and covers all of Old City North West. Old City refers to everything South of Florida

Avenue. Baist Book, Volume #2, was copyrighted in 1967 and covers all of Old City that is not in the North

West quadrant. Baist Book, Volume #3, was copyrighted in 1960 and covers all of North West that is not a part

of Old City, including Georgetown. Baist Book, Volume #4, was copyrighted in 1950 and covers all of the North

East and South East quadrants that do not fall in the Old City. This Baist Books have been georeferenced by

DC GIS.

Office of the Surveyor Document Management System

After these initial sources were examined, the documents inside of the Office of the Surveyors document

management system were researched. This document management system contains numerous, Office of the

Surveyor data sources. These sources include subdivision books, survey books, survey papers, A&T plats, record

of squares, county books and other miscellaneous map documents. It is from these documents that the specific

lengths and bearings for the reservations were found.

The subdivision books contain the most recent and official documentation of property lots in the District.

Whenever possible, it is good to use the latest subdivision book and page to determine a propertys dimensions.

In the research of a reservation it is rarely enough to simply find the latest subdivision map. It is often necessary

to look into the other sources mentioned above, like the county books and the record of squares books. These

two series of books contain property lengths and bearings, like the subdivision books, but are much older than

the subdivision books. The latest County Book is from 1909 and contains street and property data for all of the

land that fell outside of what was referred to as Washington City at the time. Originally there was Washington

County and Washington City. Washington City was everything south of current day Florida Avenue and

Washington County was everything North of Florida Avenue and Georgetown. The street and property

measurements for the old City of Washington can be found in the Record of Squares books. The Record of

Squares Books date back to the late 1790s.



Survey Books and Survey papers are another good source of bearing and dimension information. These sets of

documents were used frequently for the reservation line collection and attribution. Survey book and survey

paper information is not necessarily the legal source of record but can be very useful. The information from

these sources can be very current, and while not the necessarily the legal source of record, the information is

field accurate. Being field accurate means that the dimensions of a street, alley or lot were surveyed and

the actual precise measurements have been captured. In some cases these measurements may vary slightly

with the legal, or recorded value. As long as the survey data is current there should not be a large difference

between the recorded and the actual measurements.

Figure 2

There are many other categories of maps within the Office of the Surveyor document management system that

were useful in the data collection process including Miscellaneous Maps, Rolled Maps and Numbered

Maps. Like the data sources mentioned above, these documents often contained bearing and dimension

information. Some of these maps proved to be very useful. In the case of the Rolled Maps and some of the

Numbered Maps, these maps often times covered a large area, which made them particularly useful for larger

reservations.

A last data source from the Office of the Surveyor that is worth mentioning, are the A&T Plats. A&T Plats are

accurate for the most part, but their accuracy is not official or guaranteed. The A&T Plats main purpose is to

These documents are examples of two

different sources used in the data collection

of the federal reservations. The map on the

left is a subdivision book and page, containing

bearing and line length information. The

image above is a portion of the Right of

Way scans, which contains right of way

information as well additional helpful notes.



show lots that have been split or combined for taxation purposes. There is sometimes dimensional information

on them and they can be useful in certain places, but are generally not as accurate or reliable as the map

sources listed above.

In some instances there was enough information about the location of a reservation to look up a specific square

and lot, within the Office of the Surveyor document management System, and get all the information that was

needed. Even in these more straight forward cases, it was often necessary to do more extensive research to

make sure that there was no other relevant documentation regarding the reservation. The more extensive

research involved searching by square, and looking through each document connected to the square. The

number of documents attached to a square could range from around 10 to a couple hundred. Sorting through

all the documents could be time consuming, but was really the only way to be thorough about the research. In

many cases, if a reservation was located between two squares, all the documents from both squares would

need to be examined.

In some cases it was not good enough to simply search by square. For the more difficult reservations it was

necessary to go to the Office of the Surveyor in person, to look up information using the Office of the Surveyors

index card system. Examples of searches for documents that needed to be done in person at the Surveyors

Office include searches for street dedication documents, transfer of jurisdiction cards or to look up an area by

place name, such as Fort Dupont Park. In most cases the information that was obtained at the Surveyors

Office was a reference to a book and page, which could then be looked up on their document management

system.

Secondary Data Sources

If the map sources researched from the Office of the Surveyor document management system failed to provide

specific information, it was sometimes necessary to look into other map sources like the property scans, the

parcel scans, the parcel index cards and land transfer documents provided by the National Park Service.

The Property Scans are raster scans of squares throughout the city that are contained on microfiche in the

Surveyors Office and have been georeferenced by DC GIS. The Property Scans contain, lot, bearing and

dimension information. Some of the information may be out of date or missing but it can be a useful source for

filling in missing information.

The Parcel Scans are similar scans to the Property Scans, but they contain information to do with parcels

throughout the city rather than squares and lots. Parcels are often large tracts of land within the District that

have not been subdivided into record lots and tax lots. Parcels only reside in areas of the old Washington

County, North of Florida Avenue and Georgetown. The Parcel Scans were a helpful data source in some of the

areas that were less well documented.

It was often necessary to look up parcels when researching reservations. The only way to thoroughly research

the dimensions and the changes over time to a parcel is to look up the parcel on the Parcel Index Cards. The

Parcel Index Cards reference the evolution of a parcel as it has been altered over the years, with references to

county book and page, survey book and page and A&T book and page, which document those changes. To

gather all the necessary bearing and dimension information, it was sometimes necessary to sort through all or

many of the references on the parcel index cards.



Additional NPS Documentation

The last set of documents that were helpful in capturing a reservation came from the National Park Service. The

NPS has four different sets of documents that have to do with lands that have transferred in and out of NPS

ownership. These sets of records are the NPS General Orders, Land Transfers, Land Orders and Land Records.

These documents contain a variety of information including legal papers describing changes to a property as

well as maps, often times showing land that have been acquired or transferred by NPS. The majority of this

information does not contain length and bearing information, but there are some lengths and bearings

contained in legal descriptions and occasionally there will be survey documents included. When there is no

length or bearing information, the documents can be useful in determining if a reservation stops at a certain

point or stretches into a certain area that was not made clear by other documents.

DC GIS Data Sources

If all of the documentation failed to provide specific dimensions for a reservation, it was sometimes necessary to

use DC GIS planimetric data and DC GIS right of way polygon data. The planimetric data that was most

commonly used was street centerline data, curb line data and water line data. In some cases a subdivision book

would not provide specific bearings and dimensions but rather would reference a reservation as ending at the

curb line or at the edge of a sidewalk.

Figure 3

Source Research Summary and Example

In the creation of most of the reservations it was necessary to weigh different considerations when looking at all

the existing source data comprehensively. Sometimes, as stated earlier, it was possible to simply use the latest

subdivision book. In most cases there was contradicting data that needed to be sorted through from less

definitive sources, or there might be areas with no specific bearing and dimension information. There are too

many different scenarios like this to practically go through in this paper, but one small and simple example of

this would be a reservation whose exact measurements are not recorded in any of the Survey Office or NPS

documents. The NPS listing has a square foot value associated with the reservation and in one of the subdivision

To the left is an

example of a

reservation in

which the DC GIS

planimetric

sidewalk data was

used to help

capture the

reservation, along

with 2 subdidvision

maps from the

Districts Office of

the Surveyor.



books the lot appears to either go to the edge of the sidewalk or to the edge of the total right of way. After

measuring the square footage of the two different polygons created by the edge of the sidewalk and the edge of

the right of way boundary, it can be determined which square footage is closer to the recorded square footage

value, and this is the planimetric feature that is used to create the reservation.

Very few people have a complete knowledge of all of these data sources. There are people within the Districts

Office of Tax and Revenue, The Districts Office of the Surveyor, DC GIS, and New Light Technologies who have

the knowledge to analyze all of these different data sources in tandem. DC GIS supervised the project, and

made all the final determinations for what documents, dimensions and bearings made it into the project. There

is a narrative attribute field within each reservation line that contains the source documents and data used to

build each line. In the future, if there is ever a question or dispute, this narrative field will allow an easy way

to retrace the logic and find the proof behind the placement, the bearings and the dimensions of the

reservations.

Creation and Alignment of the New Line Work in the VPM Many of the challenges in producing the reservation dataset revolved around fitting the reservation line work

into the existing VPM data. In some fortunate cases, the line work of an existing lot was the same as the line

work for a reservation. This made the collection and placement of the reservation very straight forward. In

other cases, as mentioned above, a reservation is a median or an island, which also makes placement of the

reservation fairly straight forward. In these cases the new reservation line work is not coincident with any other

lots and therefore there are no conflicts. For these examples, lines can simply be created using the COGO tools,

by snapping new line work to the existing lines and vertices or by copying line work from other existing property

lots and squares. Squares are the units within which most lots in the district sit. Most of them are the size of

a traditional city block, bounded by three or four streets.

Figure 4

The reservation to

the left, outlined in

red, is an example

of a reservation

that is fairly

straight forward, in

that it is inside of

one square,

outlined in purple,

and runs along

existing property

lots.



COGO Toolbar and the Advanced Editing Toolset

When the COGO toolbar was used, the first step was to find a starting point to snap to. In most cases this was a

vertex or node on an existing lot, but the starting point could also be a combination of different data sources,

including the right of way polygons, the street centerlines, or the curb lines. Once a starting point was snapped

to the length and bearing values were simply entered into the traverse window. In many cases there might be

missing information for curves. It was common to have an arc length value and a radius value, but not a

directional value for a curve. If there was no chord, tangent or radial direction provided in the documentation

for a curve line, it was necessary to create every length leading up to the two endpoints of the curve and then

snap to those two endpoints with the curve tool and enter the radius for the curve in the radius window.

Three of the editing tools that were used frequently in the data capture process, were the extend, intersection

and trim tools. An example of when the extend and trim tools might be used, is if two lines are coming together

to close out a polygon. The polygon is sure to be closed out if you extend the two lines out past each other, so

that they cross. After they are extended out past each other, the trim or the intersection tool can be used to

eliminate the two over hanging lengths.

Occasionally the filet tool was used, but not very often. The filet tool could be used if there was a corner of a

reservation with no specific documented lengths or bearings that had a rounded corner. There were a few

reservations that were medians in the right of way that presented this scenario. The long lengths of the

reservation were snapped to curb line data; the lines were then extended out past each other, the overlapping

lengths were trimmed and then the filet tool was used to round the corner of the polygon.

Computed Vs. Recorded Values

There are many cases where, in order to close out a polygon created using COGO, it was necessary to either

slightly alter the length of a line or the bearing of a line. The decision was made to always keep the bearings

accurate in relation to the values in the documentation and to adjust line lengths slightly to close out polygons.

There are attributes within each line that were created In order to account for the discrepancies between the

documented dimensions of a line and the geometry that exists within the GIS. These attributes contain the

actual, or computed values of the line; meaning the true length and bearing of the line as it was created in the

GIS, as well as the recorded value; meaning the length and bearing of the line according to the official

documentation. Once the line was created, a DC GIS custom built tool was used to calculate the computed

line length and bearing. After the dimensions of the line were calculated the recorded length and bearing

were manually entered into the lines attributes. If there was no recorded value for the length or the bearing,

that was indicated as well.

Accounting For the Alignment of Neighboring Lots and City Blocks

Often times, a reservation sits along many different parcels, lots and city blocks. In most cases the lots within a

city block are quite accurate in relation to everything inside of the block, but the alignment of blocks in relation

to neighboring blocks is not as precise. In these cases city blocks and all of the lots and layers nestled inside of

them, were moved and snapped to the new reservation line work. Depending on the situation it was often

necessary to recreate neighboring lots and squares in order to have the proper bearings and coincident

geometry between neighboring polygons. ArcGISs topology tool was not used for this project because it turns

true curves into segmented curves, containing many vertices. The data cleanup that would have been required



for these curves was determined to be too much by DC GIS. DC GIS developed a custom built tool that checked

to make sure that all of the newly created polygons were closed, but beyond that no topology tools were used.

Figure 5

Benefits of the Project Now that this project is complete, there is a single dataset for any person, company or agency that needs to

know the exact size and location of a federal reservation. The detailed dataset that this project produced allows

The National Park Service and the DC Government to take a much more accurate inventory of all of their land

holdings. The new dataset highlights what areas are well documented and what portions of the federal

reservations require additional research and surveying. Because of the extensive research and data collection

that was performed during the course of this project, it will now be easier for the DC Government and the

Federal Government to transfer lands between each other, and for private citizens, who own property that

borders a federal reservation, to research and resolve property disputes or inquiries.

This project was completed by DCGIS and New Light Technologies and was made possible by the cooperation of

the DC Office of The Surveyor and their document management system.

Related Links New Light Technologies, Inc.

http://newlighttechnologies.com/

The District of Columbias DC GIS

http://octo.dc.gov/DC/OCTO/Maps+and+Apps/Geospatial+Services

DC GISs Vector Property Map

http://vpm.dc.gov/

The image to the

left shows a larger

reservation, in red,

cutting across a

number of city

blocks, whose

outlines are shown

in purple. This is

an area where the

alignment of the

city blocks is

important.



The District of Columbias Office of the Surveyor

http://dcra.dc.gov/DC/DCRA/Permits/Surveyor+Services

DC GIS Federal Reservation Data Capture Project

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