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Think . . . Spatially
Inventorying Linear Assets
From Field to GIS to Database
HILLSBOROUGH COUNTY, FLORIDA
Tampa
NorthNorth
Subdivision DevelopmentThru January 2007
Since 1986, about 30 C-L miles of new roads have been added per yearSince 1986, about 30 C-L miles of new roads have been added per year
A Growing County Lots of Point Assets
• > 96,800 Traffic Signs• > 25,000 Inlets• > 19,000 Sidewalk Ramps• > 17,000 Intersections• Nearly 5,000 Stormwater Manholes• > 1,300 Pedestrian Crossings• > 250 Bridges• > 190 Railroad Crossings
A Growing County Lots L-O-N-G Assets, Too
• > 6,700 Miles of Traffic Lanes• Nearly 4,000 Miles of Pavement Striping• > 3,200 Miles of Shoulders • > 2,600 Miles of Curbs• > 2,200 Miles of Sidewalks• > 170 Miles of Dividers• Nearly 30 Miles of Guard Rails
TOC• Overview• Linear Referencing Concepts• Field Data Collection Protocols and
Software• Route Processing Tools for Post-
processing Field Data• Best-Practices for GPS, Range-finding
and Field Data Collection• The Asset Management System
Overview
• Data Collection Using ArcGIS Engine and ArcPad
• Post Processing Using ArcGIS• Transferring Data to Asset Management
System Using Various Software Tools (Visual Basic)
Ways to Collect Linear Features
• Digitize using high-quality aerial photos• Collect a series of points, or “vertices,”
along the feature• If paralleling other linear features, such as
a street centerline (C-L), then simply collect the start and end points and take advantage of linear referencing
What We Wanted To Do
What Is Linear Referencing?
• Sometimes a picture can save on words
Routes and Linear Referencing
Offset (to right)
-Offset (to left)
FROM
TO
001000
001010
001000
R
R
L
1234
5.00
12345.00
12345.00
12345.00(Sidewalks)
Linear Referencing Concepts
• Takes Advantage of ESRI’s Dynamic Segmentation Support
• Utilizes a Linear Referencing Route System
• Converting Field-collected “Points” to Linear Features
Why Linear Referencing?
• Here’s Another Picture
Real Purty
Speed Limits
Measuring Along Routes
There is only one route (04904.00) nearby and no ambiguity.
There is only one route (04904.00) nearby and no ambiguity.
There are two routes (04899.00 and 04904.00) nearby and two different mileposts. This ambiguity can be resolved by indicating which route ID to use.
There are two routes (04899.00 and 04904.00) nearby and two different mileposts. This ambiguity can be resolved by indicating which route ID to use.
Measuring Along Routes
05827.00
05827.00.316 Mi.
.023 Mi.15.00 Ft
-15.00 Ft
Cherry Rose Cir (05827.00) starts at the intersection with Reflections Blvd. We already know about this ambiguity.
Cherry Rose Cir (05827.00) starts at the intersection with Reflections Blvd. We already know about this ambiguity.
Cherry Rose Cir (05827.00) intersects with itself about 100 feet (.023 Mi.) south of Reflections Blvd.
The route then increases from the intersection in the clock-wise direction all the way around the loop and back to the intersection.
Cherry Rose Cir (05827.00) intersects with itself about 100 feet (.023 Mi.) south of Reflections Blvd.
The route then increases from the intersection in the clock-wise direction all the way around the loop and back to the intersection.
A point at the corner, for a sidewalk end-point, let’s say, introduces a new kind of ambiguity.
The point can be either on the right of the route (15 Ft) at the smaller milepost (.023 Mi.), or on the left (-15 Ft) at the higher milepost (.316 Mi.). Either could be correct.
A point at the corner, for a sidewalk end-point, let’s say, introduces a new kind of ambiguity.
The point can be either on the right of the route (15 Ft) at the smaller milepost (.023 Mi.), or on the left (-15 Ft) at the higher milepost (.316 Mi.). Either could be correct.
Field Data Collection Concept
23
Field Data Collection Software
Street C-LPoints
Manholes
School ZoneStart and End
Field Data Collection Software
Two linear features are already being collected (Curbs and Sidewalks) as indicated by the red boxes around the icons.
Two linear features are already being collected (Curbs and Sidewalks) as indicated by the red boxes around the icons.
Field Data Collection Protocols and Software (Linear Features)
Hillsborough CountyPublic Works Department
Field Data Collection ProtocolsFor
Transportation AssetsJuly 21, 2006
Curb Endpoints
Curb Endpoints
Curb Endpoints
Street Centerline
Stre
et C
ente
rline
Stre
et C
ente
rline
Stre
et C
ente
rline
Locating Curb Endpointsat Intersections
Use the middle of the Return(the curved corner)
Inte
rsect
ion
Inte
rsect
ion
Inte
rsect
ion
Although a curb usually “drops down” at things like driveways, the curb is considered to be continuous across driveways.Typically, a curb extends for the full length of the block of a street. This is not always the case, but as a rule, curbs will have start and end points at intersections, as in the illustration, above.Another illustration of determining endpoints for curbs is shown for a cul-de-sac, below.
Field Data Collection of Lane CountsLane counts are collected for each side of a street
and includes all lanes from the edge of the road to itscenterline or divider
THRU lanes have end pointsat the center of the intersection(s)they go “thru” or into
TURN lanes have end pointswhere they reach full-width andat the edge of the intersectionthey turn into
Field Data Collection of Pavement MarkingsLong-line Pavement Markings are collected foreach side of a street and includes all markings
from the edge of the road to its centerlineor divider. Centerlines are counted on the first side of the street that is inventoried.
Markings have end pointsat the edge of the intersection(s)they go into
Changes in Markings occurwhere any new line starts ora line ends
__
BIK
E L
AN
E_
C
URB
__
DIV
IDE
R_
_ L
AN
E C
OU
NT
__
MAR
KIN
GS
__
SID
EW
ALK
__
SID
WK
HN
DR
AIL
(c)
__
SID
WK
HN
DR
AIL
(n)
__
SU
RFA
CE
TY
PE
(not
a c
ompl
ete
list
of a
ll lin
ear f
eatu
res)
X
Fiel
d D
ata
Col
lect
ion
of M
ultip
le L
inea
r Ass
sets
Exa
mpl
e of
iden
tifyi
ng th
e en
d-po
ints
of s
ever
al li
near
feat
ures
in p
aral
lel:
NO
TE th
e ve
rtica
l red
lines
indi
cate
the
loca
tion
for t
he s
tart
or e
nd p
oint
s.
__ B
IKE
LAN
E_
DIV
IDE
R_
LA
NE
CO
UNT
_ M
AR
KIN
GS
__ S
IDE
WA
LK__
SID
WK
HN
DRA
IL(c
)__
SID
WK
HN
DRA
IL(n
)__
SU
RFA
CE
TYP
E(a
s m
ore
linea
r fea
ture
s ar
est
arte
d, t
he li
st o
f ite
ms
that
can
be s
tarte
d, s
horte
ns)
X X X
__ B
IKE LA
NE_
SIDE
WALK
__ S
IDWK H
NDRA
IL(c)
__ S
IDWK H
NDRA
IL(n)
__ S
URFA
CE TY
PE
X
__ C
URB
_ D
IVID
ER
__ L
AN
E C
OU
NT
__ M
AR
KIN
GS
__ S
IDE
WA
LK
X __ B
IKE
LA
NE
_ D
IVID
ER
__ S
IDW
K H
ND
RAIL
(c)
__ S
IDW
K H
ND
RAIL
(n)
__ S
UR
FAC
E TY
PE
X
__ C
UR
B_
DIV
IDER
__ L
AN
E C
OUN
T_
MA
RK
ING
S__
SID
EW
ALK
X X
__ B
IKE
LA
NE
__ D
IVID
ER_
MA
RK
ING
S__
SID
WK
HN
DRA
IL(c
)__
SID
WK
HN
DRA
IL(n
)__
SU
RFA
CE
TYPE
X
__ B
IKE
LAN
E__
DIVI
DER
__ S
IDW
K HN
DRA
IL(c
)_
SID
WK
HNDR
AIL(n)
__ S
URFA
CE T
YPE
X
__ B
IKE
LA
NE
__ D
IVID
ER
_ S
IDW
K H
ND
RAI
L(c)
__ S
UR
FAC
E T
YP
EX
__ C
URB
__ L
ANE
CO
UN
T__
MA
RK
ING
S__
SID
EW
ALK
_ S
IDW
K H
ND
RA
IL(c
)_
SID
WK
HN
DR
AIL
(n)
X X
__ C
UR
B_
LAN
E C
OU
NT
_ M
ARKI
NG
S__
SID
EW
ALK
X X __ B
IKE
LA
NE
__
DIV
IDER
_ L
AN
E C
OU
NT
_ M
AR
KIN
GS
__ S
IDW
K H
ND
RAIL
(c)
__ S
IDW
K H
ND
RAIL
(n)
__ S
UR
FAC
E T
YPE
X X
__ C
UR
B__
LA
NE
CO
UNT
_ M
ARKI
NG
S_
SID
EW
ALK
X X
_ C
URB
_
LAN
E C
OUN
TX X
THE
MAN
Y P
OIN
T FE
ATU
RE
S D
EPI
CTE
DW
OU
LD A
LSO
BE
CO
LLE
CTE
D A
S TH
EY
AR
E E
NC
OU
NTE
RE
D, B
UT
THI
S IS
NO
TIN
DIC
ATE
D B
Y T
HIS
EXA
MPL
E.
Surface Types
Speed Limit Zones
Sidewalks
Sidewalk Handrails
Shoulders
School Zones
Road Widths
Pavement Markings
One Way
Lane Counts
Guard Rails
Dividers
Curbs
Bike Lanes
Meanwhile, Back in the Office
Meanwhile, Back in the Office
FROM_MP TO_MP
Meanwhile, Back in the Office
Voila!!
RefreshGIS View
CloseAccess
PressButton inAccess
Route Processing Steps-Concept
PressToolbarButton
Run RouteLocationWizard
SelectPoints
A custom button to activate Access®
Form w/ button to activate
update query in Access®
Using a Personal GeoDatabase . . .
Route Processing Toolbar
Create Routesfrom C-L GIS
Edit ExistingRoutes+ extend from start+ extend from end+ shorten from start+ shorten from end
Determine Measure (Milepost)and Distance (Offset) for PointData, Like Traffic Signs
Process field-collectedPoint-pairs and Create Linear Events from Them
Add EventsExport to Shape
Route Processing Toolbar
Post Processing Software
Field Data Collection Tools and Best-Practices
• Importance of a Good Centerline• GPS (Global Positioning System)• Laser Range Finding• Database Management
A Good C-L GIS Is Essential
A Good C-L GIS Is Essential
Erroneous C-L Field-corrected C-L
Two pairs of end points with PointPairIDs of
84 – Sidewalk, and87 – Curb
Two pairs of end points with PointPairIDs of
84 – Sidewalk, and87 – Curb
Even though the C-Ls are only 9 feet apart, better placement of it changes the side of the road that the curb and sidewalk are on.
Even though the C-Ls are only 9 feet apart, better placement of it changes the side of the road that the curb and sidewalk are on.
A Good C-L GIS Is Essential
• For this reason, collecting points along centerlines of streets is now part of our field data collection process.
• Points are collected at intersections, geometry changes and at points along curves.
• Back in the office, the C-L geometry is adjusted to “snap” to the field collected points.
GPS Issues
• GPS (Global Positioning System) is neither magic nor fool-proof
• Used carelessly, poor data will result• Know the short-comings and minimize
them as much as possible• Then perform quality control checks on
any data collected using GPS
GPS Issues (cont’d)• Not all GPS equipment are created equal• Satellites are constantly moving and their
“geometry” constantly changing– No two reads at the same location will be
equal– Some conditions better than others, e.g.,
PDOP (Position Dilution of Precision) values• Satellite signals can “bounce” off nearby
objects and cause errors
GPS Best-practices• Cheaper is NOT better• Use equipment/software that can control
quality (and report it)• WAAS (Wide Area Augmentation System)
should not be relied on• Set a PDOP Mask of <= 6 (4 is better)• Average multiple reads, rather than taking
only one read
GPS Best-practices• Portable, or built-in, real-time correction
beacons can sometimes improve quality• Post-processing field data using .ssf files
may improve quality• Use consistent methods in the field• Utilize double-checks in the field and in the
office
Laser Range Finder
A look to the future to improve safety and consistency: PWD is testing LRF technology.
SlopeAngle
Laser Range Finder Terms
Distance
SlopeDistance
STOP
Distance = Sin(Slope Angle) x Slope Distance
Known (X,Y)
Offset (X,Y)
Using the Distance, Azimuth and Known X,Y for the Laser, the Offset X,Y can be determined.
Laser Range Finder Issues
• Magnetic compasses affected by natural and human situations– Earth’s magnetic declination
Why can’t I get my stupid
compass to work?
Laser Range Finder Issues
• Magnetic compasses affected by natural and human situations– Earth’s magnetic declination– Nearby metal (seen or unseen)
• Distance accuracy related to aiming accuracy
• Calibration should be regularly checked and professionally corrected
Laser Range Finder Best-Practices
• Set up the laser on a tripod; hand-held “lazing” should only be used when accuracy is not required
• Make sure the laser is plumb (vertical)• Make sure you can see through the laser’s
sighting device• For long sights, work with the sun behind
you, if possible
Laser Range Finder Best-Practices
• In determining the location of the laser equipment with GPS, use multiple reads
• Use field procedures that either:– Adjust magnetic declination against a known
azimuth, or,– Collect data that can be used to adjust field
data back in the office• Minimize aiming and azimuth errors by
limiting distances “shot” in the field
Relational Database Management System (RDBMS) Fundamentals
• Most asset management systems make use of RDBMSs like Oracle or SQL Server
• Data is in a system of multiple tables that are related by various keys and codes
• This differs from a GIS feature which usually looks like a single table (attributes), unless in a GeoDatabase
Relational Database Management System (RDBMS) Fundamentals
GIS Feature
Data
RDBMS Data
User ViewingJoined Data
• Most asset management (AM) systems make use of “business rules” that control how data are coordinated.
• It is possible to join (link) a GIS feature to a table in an RDBMS, as long as both share a common key.
• Transferring data between a GIS feature table and an AM system is limited by the data management tools in the GIS and the AM’s business rules.
Relational Database Management System (RDBMS) Fundamentals
GIS Feature
Data
RDBMS Data
User and DataTransfer Tool
• Usually, an intermediate tool (software) is required to transfer data between GIS and RDBMS.
• This tool “knows” how to apply the business rules and how data are mapped between GIS attribute fields and corresponding RDBMS tables and fields.
Relational Database Management System (RDBMS) Fundamentals
• Synchronizing a GIS and an RDBMS must be able to handle:– Adding new features– Deleting (expiring) removed features– Modifying existing features
• For purposes of this presentation, GIS data supersedes that in the RDBMS, but that is not always the case
Relational Database Management System (RDBMS) Fundamentals
• Most RDBMSs do not have a “spatial” data component, out-of-the-box
• So, what about spatial data?– Usually maintained in the GIS– Recommended exceptions
• Points (store X,Y) in RDBMS, also• Linearly referenced data (store Route ID, From
Milepost, To Milepost) in RDBMS, also
Relational Database Management System (RDBMS) Fundamentals
• Why put spatial data in the RDBMS?– Belts and suspenders (redundancy)– Possibility to regenerate GIS data from the
RDBMS, using events• Points regenerate using the (X,Y) values• Linear features regenerate using linear FROM and
TO data– Allows a visual level of QA checking
Recap• Overview• Linear Referencing Concepts• Field Data Collection Protocols and
Software• Route Processing Tools for Post-
processing Field Data• Best-Practices for GPS, Range-finding
and Field Data Collection• The Asset Management System
Questions ?
[email protected](813) 307-1745