18th Annual Congress of the New Urbanism "Building Safer Streets for Healthier Neighborhoods"

Measuring Connectivity as Implementation of Sustainable Communities Strength in Numbers……..Safety in Network Powered by:

Presentation Outline
Connectivity & Safety – CNU Re-cap
Macro-scale connectivity measures
Local need for Micro-scale measures and tools
Comparing connectivity measures
Fire Station – Emergency Response
Transit Station Access (Sound Transit Pilot Study)
Sustainable Neighborhood Network Planning

Garrick / Marshall – Connectivity & Safe Streets
Better connected cities are safer
Intersection Density (better measure) & Link-Node Ratio
Both measures – difficult for people to understand intuitively
Source: Wesley Marshall and Norman Garrick | New Urban News and CNU safer less safe Characteristic Safer Cities Less Safe Cities Percent Difference Average year of incorporation 1895 1932 Average year of block development 1957 1972 Population (2000 Census) 65,719 58,845 -8.9 Real intersection density (per sq mi) 106.2 62.7 -41.0 Average block size (acres) 18.2 34.5 89.6 Link to node ratio 1.34 1.29 -3.7 Fatal crashes 3.1 10.1 225.8 Fatal crashes not on limited access highways 2.3 8.6 273.9 Source: Wesley E. Marshall and Norman Glick, Street Network Types and Road Safety: A Study of 24 California Cities

Charlier Associates - Connectivity
Connectivity Measures:
Block Length / Perimeter Length
Intersection Spacing
Link-Node Ratio
Intersection Density
Route Directness Index
Source: Charlier Associates, Scott McCarey Presentation | CNU

City of Charlotte
Leading city in application of policy and macro-level connectivity measures for transit and fire station analyses
Connectivity Ratio Response Area (sq mi) Emergency Response Service Area as a Function of Connectivity Ratio poor good Source: City of Charlotte, Danny Pleasant Study Presentation | CNU 2008

Drawbacks of Macro-Level Measures
Assumes a barrier-free landscape, measures only crow-flight distance linking selective land use.
Intersection Density Walk Score Link-Node Ratio Only reflects cul-de-sac activity - insensitive to block length. Reflects density of street development (block size). None of the methods directly measure connectivity between individual land uses (parcel-level) and they are difficult to interpret and explain to policy-makers and the general public.

Local Need for Micro-scale Measures
Macro-scale measures – key findings of public safety and establishing standards with good urban design principles
Micro-scale (direct measurement) tools are needed to advance standards at the individual land use (parcel) level.
Need Examples:
Transit Station - FTA/HUD/EPA draft policy emphasizing performance measures and importance of network and inter-modal connectivity
Sustainable Neighborhood Network Planning - non-motorized QOS (emphasis on network) in balanced, multi-modal planning - Smart Growth and / or concurrency management

Refining Route Directness Index
straight-line distance “A”
RDI = A / B actual route distance “B” B A

RDI Applied - Neighborhood Example shared-use path RDI = 0.20 RDI = 0.83 shared-use path

Comparing Connectivity Measures
Following three Case Studies compare connectivity measures:
Node-Link ratio
Intersection Density
Walk Score
Route Directness Index (RDI)
Micro-level measure success indicators:
Recognizable individual land use (parcel) connectivity, and
Sensitivity to New Urban design principles:
(a) short block, and
(b) minimal dead-ends

Fire Station / Emergency Response

RDI Baseline
RDI - Project Impact

Change in RDI
Shows affected parcels and relative impact

Fire Station Route Directness Index Before After Change Intersection Density Link-Node Ratio 55.9 56.0 0.48 0.57 19% 1.09 1.10 Walk Score 22 of 100 <1% <1% 1,115 (increased Fire Station Service Area by 17%) -- -- Parcel Impact -- -- --

Public Transport Planning

Lakewood Example
Improving Station Connections

RDI Analysis Before – without connections versus After – with connections study area is 1.0 mile radius Non-motorized connection across tracks with supporting pathways

Rail Station RDI Baseline RDI - Project Impact

Impacted parcels can be numbered for project prioritization
Rail Station RDI Change

Land Use Density and RDI taller parcels = higher land use density (address points per acre) Before After Change

Rail Station Route Directness Index Before After Change Intersection Density Link-Node Ratio 144 146 0.63 0.77 23% 1.29 1.30 Walk Score 89 of 100 1.4% < 1% 2,300 -- -- Parcel Impact -- -- --

Draft FTA Policy – Connectivity Nexus
FTA encourages the use of its funds for the type of well-designed pedestrian and bicycle amenities that attract new public transportation riders by expanding the catchment area and utility of public transportation stations.
Key requirement for determining the eligibility of a pedestrian or bicycle improvement is whether it has a functional relationship to a public transportation facility.
Pedestrian Improvements – within one-half mile
Bicycle Improvements – within three miles
(Proposed FTA Policy Statement on the Eligibility of Pedestrian and Bicycle Improvements Under Federal Transit Law. November 6, 2009)
“ ”

System-wide Transportation Planning

Anywhere USA: Variation in RDI Cul-de-sac Hybrid Grid Poor Fair Good Street Network Typology Route Directness Index Ave RDI = 0.58 Ave RDI = 0.68 Ave RDI = 0.75

Neighborhood Plan Baseline Connectivity Ped-Bike Plan

Neighborhood Plan
Impacted parcels can be numbered for project prioritization

Neighborhood Plan Route Directness Index Before After Change Intersection Density Link-Node Ratio 107 0.63 0.67 6% 1.43 1.55 Walk Score 38 of 100 9% 8% 268 -- -- Parcel Impact -- -- -- 117

City-Wide RDI Scoring: Olympia, WA
Pre-Planning Gap Analysis to
Efficiently focus expensive data collection
Begin community involvement process
Establish Concurrency Quality of Service Thresholds and Policy to Guide Site Planning
Gauge success of non-motorized projects and program (Plan) impacts on connectivity

Contact
Andy Mortensen
ViaCity Program Manager Sr. Transportation Planner
[email_address]
T 800.593.0597 Cell 503.313.6946
Bruce Haldors
President
[email_address]
T 800.593.0597 Cell 206.300.8907
www.viacity.info

Supplemental Slidedeck

Neighborhood Baseline Conditions Average RDI Scoring for Individual Tax Parcels

Impact of New Shared-Use Paths Average RDI Scoring for Individual Tax Parcels

RDI Sensitivity to Smart Growth Design Principles Block Length Cul-de-Sac Length 305 ft 330ft

Scoring Plan and Project Impacts Shared-Use Path Connections

ViaCity software

Data Needs
Aerial Photos
Transit Facilities
Ped/Bike Facilities
Ped/Bike Plans
Planned Improvements
Topography
Redevelopment plans or ideas
Parcels or Tax Lots Street Centerlines Supplemental Information (Analysis Layer) (Network Layer)

Network Editing Identify link endpoints Adapt for pedestrian-scale connections (major roads only) Add existing internal connections Add possible connections (scenarios) 1 2 3 4

Adding Impedances
Impedances apply a factor to original street centerline length
Good attributes reduce effective street length
Bad attributes increase effective street length
Original length = 1.0 mile Effective length = 0.8 mile (bike lanes, good sidewalks) Effective length = 1.2 mile (high traffic volumes, steep, no sidewalks)

ViaCity Software

RDI Analysis
Error checking
Large parcel methods
Opportunities for connections
Review statistics
Correlate to demographics

Patent pending
Transit Sites
Bike/Ped Plans
Project Prioritization
Incorporate
Impedances
Land use
Land value
Any GIS data

RDI Solutions – Work-In-Progress
Transit Station Area Project Prioritization
Cost / Benefit Analysis

18th Annual Congress of the New Urbanism "Building Safer Streets for Healthier Neighborhoods"

by Transpo Group on May 20, 2010

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18th Annual Congress of the New Urbanism "Building Safer Streets for Healthier Neighborhoods" — Presentation Transcript

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