Trb paper 12 1439 (11-23-12)
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Transcript of Trb paper 12 1439 (11-23-12)
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Making Bellevue’s Sidewalks Accessible for Everyone
TRB 2012 Annual Meeting Paper: 12-1439
Franz Loewenherz
Senior Transportation Planner
City of Bellevue (WA)
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ADA Culture of Compliance
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Title II – Government Services: Must ensure that individuals
with disabilities are not excluded from programs, services, and
activities (pedestrian facilities are an example of a program).
Americans with Disabilities Act (ADA)
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Title II Elements
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Bellevue ADA Sidewalk & Curb Ramp
Self Evaluation
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Heaving
Moveable Obstruction
Ramp cross slope
Absence of level landing
Fixed Obstruction
No Ramp Ramp Transition
Bottom Landing
Tactile Warning Top Landing
Sidewalk & Curb Ramp Inventory Overview
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Guidance for Conducting an ADA Inventory
Florida DOT
Texas DOT Maryland Highway
City of Sacramento
FHWA (1999) PROWAAC (2007)
NCHRP (2008)
Reference reports Inventory tools
AASHTO (2004)
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Data Collection
1 Database Analysis
2 Barrier Ranking
3
Disability Community Participation
Bellevue’s Approach
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Data Collection
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ADA Curb Ramp Inventory
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ADA Sidewalk Inventory
On January 22, 2004, in the case of Barden v. Sacramento, the 9th
Circuit Court ruled that sidewalks were a "program" under ADA and
must be made accessible to persons with disabilities.
FHWA guidance on grade and cross-slope:
“should be measured over 2 ft intervals, the approximate
length of a wheelchair wheelbase, or a single walking pace.”
Obstructions Running Slope Cross Slope Displacement Protrusions
1:50 (2%) max
ADAAG 4.3.7
1/4 inch max
ADDAG 4.5.2
1:20 (5%) max
ADAAG 4.8 4” max (27” - 80”)
ADDAG 4.4
36” clear width
ADDAG 4.3.3
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Coordinated staffing & funding commitment from
three agencies from three levels of government.
Technology Development Partnership
Project assessed
the applicability of
inertial profiling
technologies in
identifying existing
sidewalk and ramp
facilities that limit
access for persons
with disabilities.
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ULIP Technology
Sensor box includes:
1. a displacement laser
(texture/profile/height),
2. three accelerometers (inertial
profiling),
3. a gyroscope (pitch, roll, yaw),
4. optical trigger (reference),
5. GPS (general location), and
6. a DMI (travel distance system).
Computer and data acquisition card
are used for data capture.
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ULIP Data Transfer
Data Capture Data Acquisition
Data Processing GIS Integration
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Quality Assurance/Quality Control
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Cross Slope Running Slope Data Acquisition
Field technicians check the slope and grade of sidewalk
segment with smart level for QAQC validation of ULIP data.
Attribute Accuracy of Data
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Cross Slope Data Verification
0
2
4
6
8
10
0 8 16 24 32 40 48 56 64
Distance (ft.)
Cro
ss S
lop
e %
Smart Level Reading
ULIP Survey
ADAAG Compliance
Running Slope Data Verification
0
2
4
6
8
10
12
14
0 8 16 24 32 40 48 56 64
Distance (ft)
Ru
nn
ing
Slo
pe%
Smart Level Reading
ULIP Survey
ADAAG Compliance
ULIP data consistently
follows with the Smart
Level’s peaks and
troughs at test sites.
Rise versus Running
Distance compared to
ADAAG.
Validation Report: Smart Level/ULIP
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ULIP Grade (4 runs) vs Smart Level
0
1
2
3
4
5
6
7
8
9
80 100 120 140 160 180 200
Feet
Gra
de %
1024
1026
1027
1028
SL
ULIP Path Repeatability for Grade
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ULIP Path Repeatability for Cross Slope
ULIP Cross Slope (4 Runs) vs Smart Level
0
0.5
1
1.5
2
2.5
3
3.5
4
80 100 120 140 160 180 200
Feet
Cro
ss S
lop
e %
1024
1026
1027
1028
SL
Site was a sidewalk with two successive driveway crossings.
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ASCII text file Field Validation Mode Data in City’s GIS
Change in Level Output Reports
QA/QC
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Positional Accuracy of Data
Start/end points for each data
collection run entered on an
ortho-photo image on the ULIP’s
notebook computer screen. The
gyroscope and distance
measurement instrument were
used to compute path of travel.
Streaming GPS Sensor-based inertial navigation
Bellevue testing with global
navigation satellite system
(GPS) found the accuracy of
latitude/longitude data degraded
in areas with tall buildings or
thick tree canopies.
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Roadway Grade Analysis
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Measurement of Grade
Maximum grade is defined as a limited section of path that
exceeds the typical running grade.
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Averaging Window SIze Effect on Grade (%)
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
1325 1330 1335 1340 1345 1350 1355 1360 1365 1370 1375
Distance (Feet)
Gra
de
%
1 G
2 G
3 G
4 G
5 G
10 G
20 G
30 G
40 G
50 G
Grade and Cross Slope Averaging Window Size:
• In the ULIP Geometry Equation, the user specifies the grade and cross
slope window size in feet to be applied in a moving average computation.
• The graph illustrates the effect of moving average window size. The larger
the value, the more dampened out the features.
Raw Data Allows for Infinite Re-analysis
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User-Specified Window Size
Original profile
Smoothed profile
B
Average height
of shaded area
Current position
FHWA guidance on grade and cross-slope:
“should be measured over 2 ft intervals, the approximate
length of a wheelchair wheelbase, or a single walking pace.”
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Grade Compliance Criteria
horizontal projection
or run
30
” m
ax
.
ris
e
surface of
ramp
level
landing
level
landing
Maximum slope 8.33%
Maximum rise for any run shall be 30”
Minimum clear width shall be 36”
Level landings at bottom and top of
each ramp
An accessible route with a running slope greater than 1:20 (5%)
is a ramp and shall comply with ADAAG 4.8. (ADAAG 4.3.7)
Slope Maximum Rise (inches) Construction Type
1:20 to 1:16 (5% to 6.3%) 30 New const. & modifications
1:16 to 1:12 (6.3% to 8.3%) 30 New const. & modifications
1:12 to 1:10 (8.3% to 10%) 6 Modifications only
1:10 to 1:8 (10%- 12.5%) 3 Modifications only
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Running Slope Analysis
Allow sidewalk running slope
to match roadway grade.
- PROWAG (not ADAAG) Digital Elevation Model
134 miles of our sidewalk facilities exceed 5% grade standard.
95 miles are attributable to the adjacency of the roadway grade.
39 miles of non-standard grade sidewalk surfaces are referenced
in the City’s Transition Plan document.
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134 miles
Digital Elevation Model Calculation
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134 miles
95 miles
Digital Elevation Model Calculation
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134 miles
95 miles
39 miles
Digital Elevation Model Calculation
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Driveway Cross Slope Analysis
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Certain grades and slopes must be maintained.
2% cross-slope,
8.33% max ramp slopes if used.
Slope down at
1:12
2% cross-slope
Apron, may be any
acceptable grade Slope
up at
1:12
(8.3%)
(8.3%)
Driveway Standards
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Bellevue Design Manual
Bellevue employs a number of accessible driveway designs to maintain an
acceptable cross slope and facilitate wheelchair movement at driveways.
As reflected in DEV-7D above, securing additional right-of-way from the
adjacent property is a good strategy for improving pedestrian access on
narrow sidewalks. This design allows pedestrians to maintain a level path
as they cross the driveway.
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Driveway crossings without landings confront wheelchair users with
severe and rapidly changing slopes at the driveway flare.
A series of driveway apron flares
with 11% cross slope
measurements at 130th Avenue
SE & SE 26th Street.
Project Approach
The driveway analysis is based on ULIP
recordings taken by field staff at the center
points of driveways. Using GIS, any non-
standard cross slope values within buffer are
attributed to the driveway aprons.
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1. Over 50% of Bellevue’s 8+ percent cross slope measurements are
attributable to driveway aprons.
2. Number increases as cross slope values increase, with 70% of 10+
percent cross slope measurements attributable to driveway aprons.
3. Overall, 19% of all non-standard cross slope measurements are
attributable to driveway aprons constructed like ramps, with steep,
short side flares.
Cross Slope Findings
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ADA Viewer Interface
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ADA Viewer Window
Location
Map
Legend/
Layers
Identify/ Print
Toggle Bar Navigation
Extents
Navigation
Locate by
Address
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Barrier Ranking Analysis
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ADA tells us which features are non-standard …
... But it doesn’t tell us which of these non-standard features should be replaced first.
Compliance vs. Accessibility
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Community Outreach
Poster at Open House Mail-Back Survey Ramp Assessments
December 2007: 3 Focus Groups
April 2009: Field tour in partnership with King County
May 2009: ADA Accessibility Open House
June 2009: Written survey with more than 100 responses
Engaged people with disabilities to ensure to that we
fully understood their challenges and priorities.
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Barrier Ranking Analysis
Land
Use Streets Paths
Ramps
Islands Census
Impedance Score
Activity Score
Barrier Ranking
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Legend
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Legend
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Legend
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The ADA Sidewalk and Curb Ramp Self-Evaluation Report is
located at: http://www.bellevuewa.gov/accessibility-reports.htm
“Efforts such as those at the City of
Bellevue, Washington, that rely on the
collection of large datasets at extremely
fine spatial and temporal disaggregation
levels have the potential to significantly
automate the identification of non-
compliant locations in the field.”
NCHRP 20-07 Task 249
- Texas Transportation Institute
For More Information
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Thank you
Franz Loewenherz Senior Transportation Planner
City of Bellevue
450 110th Ave. NE
Bellevue, WA 98009
Phone: 425.452.4077