About

In order to make DDOT's LRS more useful to a variety of users, we create a variety of derivative data products to support a wide variety of usecases:

Addressing/geocoding (MAR Geocoding)
Asset management (Cityworks)
Project management (Protrack+)
Network Analysis (ArcGIS)
Safety Analysis (MIRE, Crash Data Analysis)
City Planning
Sidewalk/Pedestrian Analysis
ADA

Each one of these usecases might rely on one or more of the below LRS data products:

Block

PREVIOUSLY CALLED STREET SEGMENTS

For a city, street blocks are a very common way in which to organize and relate work (e.g. 'I need to fix a pothole on the 1600 Block of Pennsylvania Ave'). Although driveways or alleys may intersect streets, the Block segmentation requires that the segment remain unbroken. A block will always begin at a street-to-street intersection and end at the next street-to-street intersection.

Road Types included:

Streets

Segmentation Rules:

Only Streets can break/segment other streets.
Only At-grade type intersections are respected in this segmentation. See below for more information


Fig 3. Block Segment representation

Block Attributes

FIELD	DESCRIPTION	DATA TYPE	EXAMPLE
StreetSegID TEMPORARY FIELD	The old ID of this segment	Long Integer	10385 WE ARE CURRENTLY USING THIS FIELD FOR INTERNAL MIGRATION ONLY. ONCE PUBLISHED, USE 'BLOCKID' FOR UNIQUE IDENTIFIER
FromDate	When this segment was created	Date	1/1/2014
ToDate	When this segment will expire	Date	<Null>
EventID	Unique randomly generated ID	Guid	{962C2785-EE57-4B19-AEE9-D18CB5C30870}
RouteID	Unique ID of the route that this segment is on	Text	11000202
FromMeasure	The measure along the route that this segment begins (meters)	Double	0
ToMeasure	The measure along the route that this segment ends (meters)	Double	148.683739
RouteName	Name of the route on which this segment exists	Text	2ND ST NW
SegmentType	The type of segment	Short Integer	2 (Regular Single Centerline)
FromStreet	Name of streets that intersect the beginning of this segment	Text	CONSTITUTION AVE NW
ToStreet	Name of streets that intersect the end of this segment	Text	E ST NW/MITCH SNYDER PL NW
FromIntersection	ID of intersection from which this segment begins	Text	11000202_11025352A
ToIntersection	ID of intersection from which this segment ends	Text	11000202_11031332_11061392
BlockID*	Key ID for the block; it is a concatenation of the RouteID, FromIntersectionID and ToIntersectionID	Text	11000202-11000202_11025352A-11000202_11031332_11061392
BlockKey*	Primary key ID for the block. This is a GUID, which is derived from the BlockID value	GUID	053c6863e95d1ca3401417cc1adc090d
FromIntersectionKey*	Primary key ID for the From Intersection. This is a GUID, derived from FromIntersectionID	GUID	8d9cf8ca94fc3048d095388d8d3621f6
ToIntersectionKey*	Primary key ID for the To Intersection. This is a GUID, derived from ToIntersectionID	GUID	4c68cea7e58591b579fd074bcdaff740
Directionality*	Directionality of block (One way digitizing direction, one way against digitizing, two way)	Short Integer	1 [One way (Digitizing direction)]
created_user	The user that created the segment	SYS GENERATED	<Null>
created_date	The date the segment was created	SYS GENERATED	<Null>
last_edited_user	The last user that made edits to this segment	SYS GENERATED	<Null>
last_edited_date	The date the segment was last edited	SYS GENERATED	<Null>
SHAPE_length	Length of segment	SYS GENERATED	<Null>

SubBlock

PREVIOUSLY CALLED ROADWAY SEGMENTS

SubBlock represents the full extent of our centerline network. SubBlock is the finest-grained, 'base' segment from which all other segmentation patterns can be constructed (including Blocks). SubBlock is the original source features for our DDOT Street Centerlines data

Road Types included:

Streets (Code 1)
Alleys (Code 2)
Ramps (Code 3)
Service Roads (Code 4)
Trails (Code 5)
Driveways (Code 6)
Walkways (Code 7)

Segmentation Rules:

Streets, alleys, ramps, service roads and trails can break all others roadway type segments.
At-grade type intersections are respected in this segmentation. See below for more information


Fig 2. SubBlock Segment representation

SubBlock Attributes

FIELD	DESCRIPTION	DATA TYPE	EXAMPLE
RouteID	Unique ID of the route that this segment is on	Text	11037052
RouteName	Name of the route that this segment is on	Text	FORT DR NW
SubBlockID*	Intelligent key ID for the sub-block; concatenation of the RouteID, FromIntersectionID and ToIntersectionID	Text	11037052-11009492_11037052-11017482_11037052
SubBlockKey*	Primary key ID for the subblock. This is a GUID, which is derived from the SubBlockID value	GUID	16be813afac223d1e02d0deb9fba6c42
FromMeasure	The measure along the route that this segment begins	Float	135.291
ToMeasure	The measure along the route that this segment ends	Float	329.825012
FromIntersectionID	The ID of the intersection from which this segment begins	Text	11009492_11037052
ToIntersectionID	The ID of the intersection at which this segment ends	Text	11017482_11037052
FromIntersectionKey*	Primary key ID for the From Intersection. This is a GUID, derived from FromIntersectionID	GUID	82b9ad20d7eb65bb5dc336d7223bd061
ToIntersectionKey*	Primary key ID for the To Intersection. This is a GUID, derived from ToIntersectionID	GUID	55840779f58a725ae98a586b11156d06
FromSubBlock*	Name of SubBlocks that intersect the beginning of this segment	Text	ALBEMARLE ST NW
ToSubBlock*	Name of SubBlocks that intersect the end of this segment	Text	BRANDYWINE ST NW
Directionality*	Directionality of block (One way digitizing direction, one way against digitizing, two way)	Short Integer	1, One Way (Digitizing direction)
RoadType	The type of roadway it is (Street, Alley, Driveway, etc.)	Text	Street
BlockID	The BlockID of the block wherein this sub-block exists	Text	11037052-11009492_11037052-11017482_11037052
BlockKey*	Primary key ID for the block. This is a GUID, which is derived from the BlockID value	GUID	16be813afac223d1e02d0deb9fba6c42
RoadwaySegID TEMPORARY FIELD	The old ID of this segment	Text	2917 WE ARE CURRENTLY USING THIS FIELD FOR INTERNAL MIGRATION ONLY. ONCE PUBLISHED, USE 'SUBBLOCKID' FOR UNIQUE IDENTIFIER

Intersection Approach Segments

Intersection Approach Segments are short segments of the route that approach an intersection, in other words, a short section of the road leading up to an intersection.

Structure of Approach Segments

Fig 2. Approach representation

Understanding Approach Intersection Direction

Intersection direction can be a confusing attribute to understand. Its core purpose is to provide the network direction flow to the intersection point. (for each individual intersection approach)

When paired with cross-section data, this attribute gives the ability to determine if sections or lanes are approaching or departing the intersection. This may be especially important in safety analyses (such as LTS) which focus primarily upon lane and sections which are approaching (not departing) an intersection. See Fig 3 for a graphic diagram.


Fig 3. Approach intersection direction

Intersection Approach Attributes

FIELD	DESCRIPTION	DATA TYPE	EXAMPLE
RouteID	Unique identifier of the route that this approach is on	Text	11035552
ApproachID	Unique identifier of the Approach within the intersection (usually an integer value representation of the angle from the intersection).	Short Integer	270
SubBlockID	Unique identifier of the SubBlock that this approach is on	Text	11035552-11035552_47054712-11035552_47053222
IntersectionID	Unique identifier of the intersection that this approach is on	Text	11035552_47054712
FromMeasure	The begin measure of the approach (going in digitizing direction) along the route	Float	823.788
ToMeasure	The end measure of the approach (going in digitizing direction) along the route	Float	833.788
Angle	Represents the angle of the approach from the intersection	Text (needs to be changed?)	270.073777185517
Directionality	Represents the cardinal direction of the approach from the intersection	Text	West
RoadType	Represents the roadway type of this particular approach	Text	1
IntersectionDirection	This is a field which helps users determine "intersection approach lanes" with DDOT's Cross-section LRS data. Since the approaches are built in the digitizing direction, this field records inbound/outbound "approach direction". 1 = Approach direction toward the intersection point is in the same direction that of the route's measure direction. Cross-section lanes with a Lane_Dir of 1 are the approaching lanes. 2 = Approach direction toward the intersection point is in the opposite direction to the route's measure direction. Cross-section lanes with a Lane_Dir of 2 are the approaching lanes.	Short Integer	2

Blockface Segments

Blockface Segments are unbroken sections of the curb. A blockface can be made up of several subblocks, or just one subblock. Blockfaces are directional, so there will be segments on both sides of the road, each dependent on an unbroken length of curb.

Blockface segments are one of the core elements of the ParkingZones, since


Fig 2. Blockface Segment representation

Blockface Attributes

FIELD	DESCRIPTION	DATA TYPE	EXAMPLE
ROUTEID	Unique identifier of the route that this blockface is on	Text	11004002
SIDE	Which side of the route is this blockface on, when looking in digitizing direction	Text	Left
MEAS_FROM	What measure along the route does this blockface begin	Float	658.141
MEAS_TO	What measure along the route does this blockface end	Float	787.455
BLOCKFACEKEY	Unique identifier for each blockface	Text	4d547f51f668a28e0b9a652852bcdcf5
Offset	Offset value to be able to visualize the blockfaces on a map	Short Integer	-3

SubBlock Intersections

Intersections are automatically created, however they are not singular points. The LRS creates a series of points - one for each intersecting road at that intersection. For DDOT, it is more useful to have a single intersection point representing a given intersection. Through a custom DDOT script, the collection of overlapping intersection points is reduced into a single representative point and this is our SubBlock Intersections Layer.


Fig 1. Intersection representation

SubBlock Intersection Attributes

FIELD	DESCRIPTION	DATA TYPE	EXAMPLE
IntersectionID	Unique ID created by concatenating the ROUTEIDs that make up the intersection	Text	11077672_11094052
IntersectionName	Name of the intersection	Text	S ST NW & WISCONSIN AVE NW
IntersectionKey*	Primary key ID for the intersection. This is a GUID, which is derived from the IntersectionID value	GUID	0b56ed21fdb94cea77bf609468b67886
Grade	The type of intersection. For more information, check out the Intersection Grade Codes table below.	Short Integer	13, Signalized, Ped signal

Intersection Grade Codes

Code	Description	Comments
0	At Grade TEMPORARY VALUE	Generic code for indicating that the roads at this point intersect each other.
1	Not at Grade	Not at Grade is an overpass/underpass situation where the roads don't connect.
2	Undefined	Not currently defined/categorized
10	Uncontrolled	Intersection without signal or signs to stop traffic flow
11	Two-way stop	One roadway is allowed to pass without stopping
12	All-way stop	All roadways are required to stop before proceeding
13	Signalized, Ped signal	Signalized intersection with pedestrian signals
14	Signalized, No Ped Signal	Signalized intersection without pedestrian signals
15	RR crossing, Signalized	Signalized railroad crossing
16	RR crossing, Signs Only	Non-signalized railroad crossing
17	Yield Sign	Intersection with a yield sign

IntersectionRoutes

IntersectionRoutes is a 1-to-many related table to SubBlock Intersections. For each SubBlock Intersection, IntersectionRoutes contains 2 or more records - one for every intersecting route occurring at that location.

FIELD	DESCRIPTION	DATA TYPE	EXAMPLE
IntersectionID	Unique ID created by concatenating the ROUTEIDs that make up the intersection	Text	11048422_47053562
RouteID	The Unique ID for this particular route geometry	Text	11048422
Measure	The LRS m-value (in Meters) along this route at the point of intersection.	Double	213.113

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