View
728
Download
0
Category
Tags:
Preview:
DESCRIPTION
CNU Summit 2009 RDI
Citation preview
measuringmeasuring
Transportation ConnectivityTransportation Connectivitybyby
Route Directness IndexRoute Directness Index
usingusing
*
* Trademarks provided under license from ESRI.
2009 Transportation Summit – Portland, Oregon2009 Transportation Summit – Portland, Oregon
Background Policy IssuesBackground Policy Issues
Complete Streets Policy Concurrency Program Refinements VMT and GHG per Capita Reduction Multi-Modal Level-of-Service (LOS) Street Connectivity Policies
Connectivity between new/existing developed lands Non-motorized public accessways and limiting cul-de-sacs Grid-based standards for streets (500 feet ) and Non-motorized (330 feet) –
emphasis on smaller block lengths Developing connectivity metrics
Cities are looking at a host of transportation, land use, energy, environmental and sustainability Cities are looking at a host of transportation, land use, energy, environmental and sustainability policy issues and considering new measurement techniques:policy issues and considering new measurement techniques:
Testing Connectivity MetricsTesting Connectivity Metrics
Link / Node Ratio
Intersection Density
% 4-Way Intersections
Route Directness Ratio
1990’s Hierarchical Network
1990’s Hierarchical Network1950’s Grid Network
A B
C D
A B
C D
261 / 146 = 1.79
107
40 %
.74
158 / 143 = 1.10
93
20 %
.44
(Miles on Perimeter Arterial)0.4 2.7
Connectivity measurements in small subareas are straight-Connectivity measurements in small subareas are straight-forward; but what about city-wide?forward; but what about city-wide?
Achieving VMT per Capita ReductionAchieving VMT per Capita Reduction
-25
-20
-15
-10
-5
0
% C
han
ge i
n P
ers
on
Mil
es T
ravell
ed
Residential Office Park Retail / Service
Land Density Land Use Diversity Design
DESIGNAverage Block Size
% 4-Way Intersections% Sidewalk Coverage- 4 %
- 2 %
- 5%
Measures of connectivity help indicate transportation-efficient Measures of connectivity help indicate transportation-efficient land uses that yield lower VMT and GHG per capitaland uses that yield lower VMT and GHG per capita
Research conducted in Seattle area by C. Lee and Anne Moudon (University of Washington), 2006: Quantifying Land Use and Urban Form Correlates of Walking
Intersection DensityIntersection Density
Intersection Density 4-Way Intersection Density
GIS mapping techniques can illustrate city-wide measures of intersection density GIS mapping techniques can illustrate city-wide measures of intersection density but have difficulty illustrating “Plan” benefitsbut have difficulty illustrating “Plan” benefits
Link-Node, Intersection Density and Walkscore Measures are only Link-Node, Intersection Density and Walkscore Measures are only ProxiesProxies for for connectivity – RDI is a direct measure of connectivityconnectivity – RDI is a direct measure of connectivity
Composite Accessibility IndicesComposite Accessibility Indices
Can help identify and prioritize plans, but miss the important measure of system Can help identify and prioritize plans, but miss the important measure of system connectivity and notable gaps.connectivity and notable gaps.
Defining RDIDefining RDI
Define Route Directness Index
The Route Directness Index (RDI) can be used to quantify how well a street network connects destinations.
The RDI can be measured separately for motorized and non-motorized travel, taking into account non-motorized shortcuts, such as paths that connect cul-de-sacs, and barriers such as highways and streets that lack sidewalks.
The RDI is calculated by dividing direct travel distances by actual travel distances. For example, if streets are connected, have good sidewalks, and blocks are relatively small, people can travel nearly directly to destinations, resulting in a high index. If the street network has many unconnected dead-ends and blocks are large, people must travel farther to reach destinations, resulting in a low index.
RDI CreditsRDI Credits
Jennifer Dill, Portland State University Research – Connectivity Metrics
Victoria Transport Policy Institute Policy – Connectivity Metrics
Charlier & Associates & Otak Intl. – CNU Practice
Others
RDI Example: RDI Example: Pre Neighborhood Pre Neighborhood ConnectorConnector
Route Directness Index can better illustrate “before-Route Directness Index can better illustrate “before-and-after” Plan improvementsand-after” Plan improvements
Existing Shared-Use Path
Route Directness IndexRoute Directness Index
Crow FlightCrow Flight
Walk DistanceWalk Distance
1850 ft1850 ft
1850 ft1850 ft
RDIRDI
RDI: .20RDI: .20
.20.20
//
==
375 ft375 ft
375 ft375 ft
Route Directness Index can better illustrate “before-Route Directness Index can better illustrate “before-and-after” Plan improvementsand-after” Plan improvements
RDI Example: RDI Example: Post Neighborhood Post Neighborhood ConnectorConnector
Existing Shared-Use Path
Route Directness IndexRoute Directness Index
Crow FlightCrow Flight
Walk DistanceWalk Distance
RDIRDI
==
375 ft375 ft
375 ft375 ft
RDI: .83RDI: .83
.83.83
New Neighborhood
Connectors
450 ft450 ft
450 ft450 ft
//
RDI – GIS Focal ExamRDI – GIS Focal Exam
Testing RDI on a larger, city-wide scale is the challengeTesting RDI on a larger, city-wide scale is the challenge
Poor
Good
Examples Using RDI DesktopExamples Using RDI DesktopTMTM
Access to Commuter Rail Station
Bike Access to LRT Station
Pedestrian Access to LRT Station
Neighborhood Design / Growth Management
Non-Motorized Concurrency and Quality of Service
Using Using RDI DesktopRDI Desktop to to demonstrate functional demonstrate functional implementation of a implementation of a Master Master PlanPlan area: area:
• Measuring connectivity Measuring connectivity with & without with & without exclusive exclusive pedestrian routespedestrian routes
RDI Measure: Neighborhood Connectivity
Growth Management: Growth Management: Non-Motorized Concurrency and Non-Motorized Concurrency and
Quality of ServiceQuality of Service11
Planned NeighborhoodPlanned Neighborhood Neighborhood design:
Mixture of villa plot size
Neighborhood centers
Maximized public realm for non-motorized connectivity through: Quality street
pedestrian zone Connecting
exclusive exclusive pedestrianpedestrian routes, and park/open spaces
Neighborhood RDI ScoreNeighborhood RDI ScoreMeasured
without PedestrianPedestrian connections
Fair RDI scores
Poor
Fair
ExcellentParcelParcel
RDI DesktopTM Metric
ParcelParcel
Average RDI Score: Fair .65
Neighborhood RDI ScoreNeighborhood RDI ScoreMeasured with
PedestrianPedestrian connections
Good-Excellent RDI scores
Poor
Fair
Excellent
ParcelParcel
RDI DesktopTM Metric
ParcelParcel
Average RDI Score: Good .73
RDI scoring can be used to establish non-RDI scoring can be used to establish non-motorized motorized concurrency measuresconcurrency measures and and thresholds, used to evaluate future land thresholds, used to evaluate future land development plans for policy compliancedevelopment plans for policy compliance
Comparative RDI ScoringComparative RDI ScoringRDI Score
Difference: With and Without Pedestrian Pedestrian connections
ParcelParcel
RDI DesktopTM Metric
ParcelParcel
Plots that benefit significantly Plots that benefit significantly by by PedestrianPedestrian connectivity connectivity
Intersection Density ScoringIntersection Density ScoringIntersection
Density Score Without SUPsSUPs
Poor
Fair
Excellent
Average Density Score: Poor 68
Intersection Density ScoringIntersection Density ScoringIntersection
Density Score With SUPsSUPs
Fair
Average Density Score: Good 142
Poor
Excellent
Link-Node ScoringLink-Node ScoringNode-Link
Score Without SUPsSUPs
Link-Node Ratio: 1.66
Link-Node ScoringLink-Node ScoringNode-Link
Score With SUPsSUPs
Link-Node Ratio: 1.67
Seattle’s Mt. Baker Seattle’s Mt. Baker Link LRT Station Link LRT Station
ExampleExample
RDI Measure: Pedestrian Access to LRT Station
Establish GIS DatabaseEstablish GIS Database Study area Light rail line Street centerline Parcel data
Create Pedestrian NetworkCreate Pedestrian Network Create Pedestrian
Network Illustrate
Importance of “Hanford Steps”
Calculate Base Year RDICalculate Base Year RDI Study Parcels
(2,000 foot radius buffer from LRT station)
Pedestrian RDI to Mt. Baker Station
Baseline Conditions (assumes no Hanford Steps)
RDI Average = 0.67
ParcelParcel
RDI DesktopTM Metric
StationStation
Average RDI Score: Fair .67
Poor
Good
Calculate PMP RDICalculate PMP RDI Pedestrian RDI to
Mt. Baker Station RDI Impact of
Hanford Steps
Poor
GoodParcelParcel
RDI DesktopTM Metric
StationStation
Average RDI Score: Good .72
Estimate RDI EnhancementEstimate RDI Enhancement Pedestrian RDI to
Mt. Baker Station Difference between
Baseline RDI and Hanford Steps RDI
Baseline: 58% of parcels above RDI 0.65 threshold.
Steps RDI: 73% of parcels above threshold.
Additional 40 more parcels.
RDI scoring can be used to sharpen plan RDI scoring can be used to sharpen plan priorities, particularly as federal and state priorities, particularly as federal and state
funding becomes more competitivefunding becomes more competitive
Intersection DensityIntersection Density Without link Average: 296
intersections per mi2
Poor
Good
Average Density Score: Fair 296
Intersection DensityIntersection Density With project Average: 302
intersections per mi2
Marginal increase
Average Density Score: Fair 302
Poor
Good
Seattle’s Beacon Hill Seattle’s Beacon Hill Link LRT Station Link LRT Station
ExampleExample
RDI Measure: Bike Access to LRT Station
Import GIS DatabaseImport GIS Database Study area Light rail line Street centerline Parcel data
Create Bicycle NetworkCreate Bicycle Network Create bike network Bicycle Master Plan
– existing conditions (2004)
Route Choice AnalysesRoute Choice Analyses Route Directness
Index
Weighted Distance based on bicycle network characteristics Weighted Distance = Distance / [ [ x * (0.80) + y * (0.20)] * (0.10) ]
Impedancewhere Bike Facility Type (FT) Score (x) SDOT Code
Shared-Use Path 10 9, 23Bike Boulevard 9.5 8Bike Lane (both sides) 8 1, 16Bike Lane (one side) 6 2, 19Sharrow 5 3, 14Shared Lane 5 30, 40Shared (arterial) 2 10Shared (other) 0 15, 21, 77
Slopeand Slope Score (y)
< 2 % 102 - 4 % 84 - 8 % 58 -12 % 3> 12 % 0
Calculate Base Year RDICalculate Base Year RDI Study parcels (one-
mile link distance) Routes from parcels
to Beacon Hill Station
Existing Conditions (2004)
Poor
Good
Calculate BMP RDICalculate BMP RDI Added Bike Lanes
noted in Bicycle Master Plan (BMP)
Poor
Good
Estimate RDI EnhancementEstimate RDI Enhancement Difference between
Existing RDI and BMP RDI
Alternatives AnalysisAlternatives Analysis Testing new Bicycle
Boulevard project to improve E-W connectivity
Poor
Good
BMP oriented mostly
north-south (arterials)…
…instead of to LRT sta.
RDI scoring can be used to identify RDI scoring can be used to identify supplemental master plans, using supplemental master plans, using
detailed route-choice analyses that detailed route-choice analyses that integrate walkability and bicycle integrate walkability and bicycle
compatibility indicescompatibility indices
RDI ComparisonRDI Comparison Difference between
BMP RDI and RDI with added Bike Boulevard project
Connectivity to LRTConnectivity to LRT
Poor
Good
Poor
Good
Baseline Measure:Baseline Measure:
Bicycle Master Plan
Plan Refinement:
New Bicycle Boulevard
Bicycle System Connectivity ScoresBicycle System Connectivity Scores
Project Impact:
Improved Connectivity
Non-motorized System Plan Non-motorized System Plan EvaluationEvaluation
RDI Measure: Pedestrian Network Connectivity
Existing ConditionsExisting Conditions
Shared-Use Path Connections
Average RDI Score: Poor / Fair .58
New Shared-Use PathsNew Shared-Use Paths
Shared-Use Path Connections
Average RDI Score: Fair / Good .66 14 % improvement
RDI – “Before & After”RDI – “Before & After”
Shared-Use Path Connections
Sensitive to Block Sensitive to Block LengthLength
Sensitive to Cul-de-Sensitive to Cul-de-Sac LengthSac Length
305 ft 330ft
RDI scoring is sensitive to urban design RDI scoring is sensitive to urban design principles – because it directly measures principles – because it directly measures
connectivityconnectivity
RDI – “Before & After” DeltaRDI – “Before & After” Delta
Shared-Use Path Connections
Link-Node: BeforeLink-Node: Before
Link-Node Ratio: 1.45
Nodes 74
Links 107
Ratio 1.45
Shared-Use Path Connections
Link-Node: AfterLink-Node: After
Shared-Use Path Connections
Link-Node Ratio: 1.53 5.5 % improvement
Nodes 92
Links 141
Ratio 1.53
Lakewood Lakewood Sounder Commuter Rail Station Sounder Commuter Rail Station
ExampleExample
RDI Measure: Access to Commuter Rail Station
Shared-Use Path
Bike Lanes & Sidewalks
Non-Motorized Railroad Overpass
I-5 Overpass Retrofit / Bike Lanes and Sidewalks
Option A
Option B
Sounder Commuter Rail
St Claire Hospital
115th Street
47th
Aven
ue
Non-Motorized Improvement Options
"Sharrow" - Shared-Lane
112th Street
111th Street
Lakevie
w A
ve.
Bri
dg
ep
ort
Way
Bike Lanes
Lakewood’s NMTPLakewood’s NMTPNew Pedestrian-Bicycle ConnectionsRR Over-crossing
I-5 Over-crossing
RDI - BaselineRDI - Baseline Testing RDI: Land Use – to
Sounder Station Land Use (building
structures) within One-Mile Radius
“Baseline” = Existing Pedestrian System Connectivity
Poor
Fair
Good
RDI – After I-5 CrossingRDI – After I-5 Crossing Impact of I-5 Over-Crossing
Improvements Addition of Sidewalks and
Bike Lanes
Poor
Fair
Good
RDI – After RR CrossingRDI – After RR Crossing Impact of New Railroad
Over-Crossing Exclusive Non-Motorized
Facility
Poor
Fair
Good
Why Use Route Directness IndexWhy Use Route Directness Index
RDI metric can enumerate important quality of connectedness, a primary factor (along with land mix and density) in urban transportation sustainability by: Directly measuring street / pathway connections, rather than proxy measures, and Mapping spatial variation in land use connectivity
RDI calculates numerical metrics to evaluate the quality of a connection between an origin location and one or more destinations. These metrics can be mapped thematically at the origin location to highlight areas of connectivity quality (range, good-bad).
Using these metrics, before and after analyses can be performed to quantify and locate the impacts of improved connections (especially non-motorized connections), establishing Comparative RDI Benefit to Existing Land Use
Route Choice ModelingRoute Choice Modeling Non-motorized
system quality, or levels and types of obstacles (impedances) are important factors to consider in walking and cycling route choice sub-models
How Can RDI DesktopHow Can RDI DesktopTMTM Help? Help?
Street Design Policy Implementation – measurable guidelines
Establish Non-motorized Neighborhood Connectivity Standards Design guide thresholds for neighborhood planning site plan review – non-
motorized concurrency
Non-Motorized Plan Strategic Prioritization Measure current networks - target critical non-motorized connections Minimizing expensive and unnecessary data collection Help expedite Draft Non-motorized Plan project identification and priorities Consistently evaluate and rank multi-modal projects for federal
Transportation Enhancement Program grant applications
Critical Plan Priority Analysis and Ranking – consistent and robust technique (with other sub-models) to measure important: Neighborhood Connectors Transit Access Connectors Urban Boulevard Crossings
ContactContact
Andy Mortensen Andy Mortensen
WHAT TRANSPORTATION CAN BE
andy.mortensen@transpogroup.com
503.313.6946
www.transpogroup.com
Abu Dhabi | Kirkland | Seattle | Boise
* Trademarks provided under license from ESRI.
*
Recommended