![Background Policy Issues ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Cities are looking at a host of transportation, land use, energy, environmental and sustainability policy issues and considering new measurement techniques:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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CNU Summit 2009 RDI
- 1. measuring Transportation Connectivity by Route Directness Index using * * Trademarks provided under license from ESRI. 2009 Transportation Summit – Portland, Oregon
- 4. Achieving VMT per Capita Reduction - 4 % - 2 % - 5% Measures of connectivity help indicate transportation-efficient land 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
- 5. Intersection Density Intersection Density 4-Way Intersection Density GIS mapping techniques can illustrate city-wide measures of intersection density but have difficulty illustrating “Plan” benefits Link-Node, Intersection Density and Walkscore Measures are only Proxies for connectivity – RDI is a direct measure of connectivity
- 6. Composite Accessibility Indices Can help identify and prioritize plans, but miss the important measure of system connectivity and notable gaps.
- 9. RDI Example: Pre Neighborhood Connector Route Directness Index can better illustrate “before-and-after” Plan improvements Existing Shared-Use Path Route Directness Index Crow Flight Walk Distance RDI / = 1850 ft 1850 ft RDI: .20 .20 375 ft 375 ft
- 10. RDI Example: Post Neighborhood Connector Route Directness Index can better illustrate “before-and-after” Plan improvements Existing Shared-Use Path Route Directness Index Crow Flight Walk Distance RDI = New Neighborhood Connectors / 375 ft 375 ft RDI: .83 .83 450 ft 450 ft
- 11. RDI – GIS Focal Exam Testing RDI on a larger, city-wide scale is the challenge Poor Good
- 39. Connectivity to LRT Baseline Measure: Bicycle Master Plan Plan Refinement: New Bicycle Boulevard Bicycle System Connectivity Scores Project Impact: Improved Connectivity Poor Good Poor Good
- 41. Existing Conditions Shared-Use Path Connections Average RDI Score: Poor / Fair .58
- 42. New Shared-Use Paths Shared-Use Path Connections Average RDI Score: Fair / Good .66 14 % improvement
- 43. RDI – “Before & After” Shared-Use Path Connections Sensitive to Block Length Sensitive to Cul-de-Sac Length 305 ft 330ft RDI scoring is sensitive to urban design principles – because it directly measures connectivity
- 44. RDI – “Before & After” Delta Shared-Use Path Connections
- 45. Link-Node: Before Link-Node Ratio: 1.45 Nodes 74 Links 107 Ratio 1.45 Shared-Use Path Connections
- 46. Link-Node: After Shared-Use Path Connections Link-Node Ratio: 1.53 5.5 % improvement Nodes 92 Links 141 Ratio 1.53
- 48. Lakewood’s NMTP New Pedestrian-Bicycle Connections RR Over-crossing I-5 Over-crossing
Notes de l'éditeur
- Cities are looking for additional tools to help them plan for multi-modal transportation systems. Even the most sophisticated travel demand models do not estimate and assign non-motorized traffic to the transportation network. Recent national studies in the development of multimodal level-of-service (LOS) techniques have not been well-received by practicing planners and engineers who are focused on pedestrian and bicycle systems . Planners and engineers are seeking new measures to better illustrate the range of non-motorized system connectivity, to help prioritize multi-modal plan projects. Rather than focus on estimating measures on non-motorized travel demand , this study focuses on measuring non-motorized system performance in the form of network connectivity
- Link/Node ratio – National studies estimate 1.4 as the connectivity threshold for “walkable” neighborhoods/network. Route Directness Ratio – the closer to 1.0, the greater the connectivity. Also consider additional GIS measures that expand on baseline measures, measures that require greater database development and analytical techniques. Sidewalk Coverage or More Detailed Walkability Ratings Bike ability Scoring Affects of Pedestrian and & Bicycle System plan priority connectors Connectivity scoring could be input in (1) Pedestrian and Bicycle system plan prioritization and (2) refined Concurrency policy/program
- Network Connectivity – Street Design – Is only one of several important factors in transportation-efficient land use planning, it’s the smaller of the 3 D factors affecting person miles traveled. Together quality land use mix, density and a well-connected street/pedestrian system yields significantly lower VMT and GHG per capita. Distinguishing measures of DESIGN include average block size, % 4-way intersections and % sidewalk coverage. In reality, while strong indicators, all three measures are only proxies of connectivity. There is a need for a uniform and direct measure of connectivity – land use/transportation relationship.
- Testing Olympia GIS Data for Intersection Density Metrics. As proxies , intersection density metrics can be mapped, but are difficult to then illustrate the benefit of planned, non-motorized system improvements; nor do they reflect the actual system network quality of walking and bicycle travel.
- Composite Accessibility Indices (layering analysis) are helpful in identifying pedestrian or bicycle system improvement priorities, but do not provide measure of non-motorized system connectivity nor baseline system measures to gauge plan success and progress. The RDI can supplement composite accessibility measures in establishing Plan priorities, plus quantify system connectivity.
- Similar to Bicycle network, Transpo RDI Tool used to calculate pedestrian connectivity between tax lots and LRT station. Weighted Distance calculation in ESRI’s Network Analyst estimating Bicycle Route Choice: distance and existing vs. missing sidewalks with travel impedance. Additional variables can be added to route choice calculator: pedestrian environment (walkability factors and amenities), vehicle travel lanes, vehicle volume, and vehicle speed.
- Similar to Bicycle network, Transpo RDI Tool used to calculate pedestrian connectivity between tax lots and LRT station. Weighted Distance calculation in ESRI’s Network Analyst estimating Bicycle Route Choice: distance and existing vs. missing sidewalks with travel impedance. Additional variables can be added to route choice calculator: pedestrian environment (walkability factors and amenities), vehicle travel lanes, vehicle volume, and vehicle speed.
- Slide illustrates the RDI calculation for a select O-D pair of dwellings within a hierarchical (non-grid, cul-de-sac focused) neighborhood.
- Slide illustrates the RDI calculation reflecting enhanced neighborhood connections.
- Testing Olympia GIS Data for RDI at the neighborhood and city-wide scale: the challenge .
- Four examples of applied use – Transpo RDI Desktop
- In Washington State, Concurrency/Growth Management/Sustainability policy direction – seeking multi-modal quality-of-service (QOS) measures. System-wide RDI scoring for pedestrian and bicycle connectivity surpasses other system “proxy” measures.
- NLR not very helpful in analyzing Plan improvements when street base is already connected with few dead-ends
- Pedestrian Access to Light Rail Transit
- Seattle DOT has prepared a Pedestrian Master Plan, with several arterial crossing recommendations, acknowledging sidewalk and pedestrian bridge projects within the LRT station area. Plan developed concurrent with LRT line and station area planning.
- ESRI Network Analyst used to create Pedestrian Network, using City’s centerline file and PMP profile- pedestrian facility types
- Baseline conditions note poor pedestrian connectivity in southwest LRT station area – very hilly terrain .
- Transpo RDI Tool used to model importance of “Hanford Steps.” Significant connection, remaining “poor” RDI parcels subject to large tax lots and missing internal (private connections).
- Exercise illustrates strength of Transpo RDI Tool use: Testing RDI scores of individual pedestrian plan projects, identifying and ranking priority LRT station area access improvements with a consistent measurement tool Ability to weight project RDI scoring with land use – socio-economic profile (e.g. low income, transit-dependent residents) Integrated non-motorized and LRT planning – helps “train the Planner’s eye” for LRT accessibility issues and solutions.
- Transpo RDI Tool used to model importance of “Hanford Steps.” Significant connection, remaining “poor” RDI parcels subject to large tax lots and missing internal (private connections).
- Bike Access to Light Rail Transit
- Initial steps to prepare base GIS files for RDI calculation to measure bicycle access to LRT stations.
- Seattle DOT had prepared a Bicycle Master Plan, with several route enhancement recommendation within the LRT station area. Plan pre-dated LRT line and station area development. ESRI Network Analyst used to create Bicycle Network, using City’s centerline file and BMP route profile- bicycle facility types
- Transpo RDI Tool used to calculate bike connectivity between tax lots and LRT station. Weighted Distance calculation in ESRI’s Network Analyst estimating Bicycle Route Choice: distance and route slope, varying travel impedance by bike facility type. Additional variables can be added to route choice calculator: vehicle travel lanes, vehicle volume, and vehicle speed. METRO Portland is finalizing bicycle route choice model parameters and variables for future use.
- Base year RDI score for tax parcels calculated using baseline street system.
- Impact of Seattle’s BMP: new bicycle lane on busy arterial. Significant enhancement to bicycle – LRT access in SE quadrant of station area.
- Plotted “Delta” between Base Year and Impact of Bicycle Master Plan.
- Even with BMP enhancements, there remains relatively poor connectivity between NE and SW neighborhoods and the LRT station. Transpo RDI Tool used to test additional Bicycle Boulevard enhancement.
- Exercise illustrates strength of Transpo RDI Tool use: Supplemental to long-range non-motorized plans which pre-date LRT route and station area plans – helps identify new or modified project priorities Integrated non-motorized and LRT planning – helps “train the Planner’s eye” for LRT accessibility issues and solutions.
- Impact of Seattle’s BMP: new bicycle lane on busy arterial. Significant enhancement to bicycle – LRT access in SE quadrant of station area.
- Building GIS database to measure “crow flight between potential origin-destination pairs (example: tax lot-to-tax lot). Base values reflect averaged RDI for each tax lot origin, with destinations originally set at a one-half mile maximum walking distance.
- RDI re-calculated based on added shared-use path connectors
- Note RDI measures for tax lots in relation to adjacent block length and cul-de-sac length
- A delta plot is easily mapped to illustrate the tax lots which directly benefit from improved access, or connectivity.
- Building GIS database to measure “crow flight between potential origin-destination pairs (example: tax lot-to-tax lot). Base values reflect averaged RDI for each tax lot origin, with destinations originally set at a one-half mile maximum walking distance.
- RDI re-calculated based on added shared-use path connectors
- Pedestrian Access to Commuter Rail
- New Sounder Station in Lakewood, Washington Commuter Rail route to Tacoma and Downtown Seattle Non-Motorized Plan identifies Interstate Freeway and Railroad Over-crossing enhancements, major impediments to bicycle and pedestrian travel and access to new Sounder Station.
- Transpo RDI Tool used to model “Baseline” or existing access/connection from neighboring land use to commuter rail station. Significant rail and freeway barrier to non-motorized connectivity, much of commuter station catchment area RDI is Fair to Poor.
- Transpo RDI Tool used to model I-5 Over-crossing enhancements. Significant improvement to non-motorized RDI south of I-5.
- Transpo RDI Tool used to model Sounder railroad Over-crossing and connection enhancements. Significant improvement to are-wide RDI.