Chittenden County Land Use - Transportation Decision Support System
description
Transcript of Chittenden County Land Use - Transportation Decision Support System
Chittenden County Land Use -
Transportation Decision Support
System
http://www.ccmpo.org/planning/dss
November 19, 2003
Chittenden County Metropolitan Planning OrganizationChittenden County Regional Planning Commission
Vermont Agency of Transportation
Presentation Overview
• Why use the DSS?
• Use of DSS within Planning Processes
• Structure of Decision Support System (DSS) Software
• Current Test Results
What is the Land Use-Transportation
Decision Support System (DSS)?• A free-standing, GIS-embedded software
that examines the interrelationships of transportation and land use, and provides outputs in support of local and regional planning processes.
• The outputs have been designed to assist stakeholders and decision-makers in:
1. Assessing Existing Conditions2. Creating Plans3. Implementing Plans4. Achieving Plans
Why DSS?
• Better integration of transportation model with more detailed land use modeling capabilities.
• Tool for examining influences of large “regionally significant” projects.
• Visual and quantitative information to assist policy boards in making decisions.
• Output informs planning process.
Step #1 Identify Values
Step #5Develop
Alternative Plans
Step #2Determine Indicators
Step #4Evaluate
Current Conditions
Step #6Evaluate
Alternative Plans
Step #3Develop
Assumptions
Step #7Adopt Desired
Plan
In Support of Planning
DSS Software Overview
• Snapshot Mode– Parcel Based
• Forecast Mode– Resizable Grid
(50-200 acres)
200 acre grid
Snapshot results screen
“Snapshot” Analysis
• Static, Parcel based analysis• Useful in examining specific
development proposals• Does not automatically forecast future
development • Training for Local Planners completed
on July 24, 2002• Pilot studies ongoing in Shelburne and
Charlotte
Forecast Analysis
• Forecasts location of future housing and employment and associated travel demand
• Useful in examining projects with Regional Impacts
Required Inputs for DSS Forecast Mode
Environm ental Constraints(septic suitability, steep slopes,
wetlands, etc.)
Existing Housing andEm ploym ent
DecisionSupportSystem
Software
Ind icators Transportation
Dem and Housing and
Em ploym entG rowthA llocations
M aps of"A ttractiveness"
Regional Projections of HousingDem and and Em ploym ent
Growth
Land Use Scenario(perm itted land uses, allowable
densities, etc)
Municipal andTransportation Infrastructure
Changes
Existing Conditions
Forecast Conditions
Existing Municpal andTransportation Infrastructure
Chittenden CountyResidential
Zoning
Chittenden CountyNon-Residential
Zoning
Forecast Accessibility
• The “Accessibility” is calculated for each grid cell
• Accessibility is an objective measurement that describes the convenience and efficiency of traveling between locations
• Accessibility is the inverse of travel time between locations factored to reflect:– The number of origins and destinations
– The grid cell’s proximity to roadways
TAZ-Level Accessibility
Smoothed TAZ-level Accessibility
Distance to Local Streets
Factored Grid-level Accessibility
Forecast Attractiveness
• The “Attractiveness” is calculated for each grid cell
• Each cell’s Accessibility measure is factored to reflect development incentives and/or disincentives
Septic Soil and Municipal Sewer Parameters
NOTE: These data reflect the 1996 on-site rules
Potential Attractiveness Factors
Municipal Sewer Service Area
105%
Conventional Septic
100%
Mound System
95%
Unsuitable 85%
Housing and Employment Allocation
• Based upon the final Attractiveness “scores”, all developable cells are grouped into 10 deciles
• The DSS then assigns 50% of the new housing and employment into first decile, 25% into second decile, 12.5% into third decile, etc.
• If a decile cannot absorb the appropriated growth, then the excess development goes into the next decile
• Within each decile, the cells are randomly chosen
DSS ForecastHypothetical Tests
Two Rounds of Testing
Round 1 4 Scenarios:• 1A - Base land use and transportation network • 1B - Increased density allowances throughout Region• 1C - Five-lane Route 7• 1D - Increased density allowances and Five-lane
Route 7
Round 2 4 Scenarios• 2A – Base land use and transportation network• 2B – Base land use and express bus service to Jericho
& new Milton interchange• 2C – TOD land use and Base transportation network• 2D – TOD land use and express bus service to Jericho
& new Milton interchange
Single-Family ResidentialHypothetical Testing Scenario 1A
Base Land Use and Base Transportation Network
Accessibility to
Employment (2024)
Hypothetical Testing Scenario 1BExtreme Land Use and Base
Transportation Network
Single-Family ResidentialHypothetical Testing Scenario 1A
Base Land Use and Base Transportation Network
Attractiveness (2024)
Hypothetical Testing Scenario 1BExtreme Land Use and Base
Transportation Network
Volume to Capacity RatioHypothetical Testing Scenario 1A
Base Land Use and Base Transportation Network
Hypothetical Testing Scenario 1BExtreme Land Use and Base
Transportation Network
Comparison of Housing Growth Allocation
Base Case vs. Extreme Scenarios
Comparison of Employment Growth Allocation
Base Case vs. Extreme Scenarios
General Conclusions
• Land use policies have a stronge influence on Accessibility and Attractiveness
• Influence of land use policies dampened by the influence of transportation improvements
• Transportation improvements in the urban/suburban core of the County create more accessibility in the Transition and Rural Planning Areas
• Existing high allowances for non-residential growth are only slightly impacted by changes to transportation system and/or land use policies
• Current land use policies can not accommodate anticipated housing demand
Steering Committee Recommendation
• Recommended to CCMPO/CCRPC Boards the DSS software is an appropriate tool to assist in local and regional land use and transportation planning processes.
Next Steps• Model development is an ongoing process.
• DSS provides better information for planning.
• DSS provides the best analysis possible to date, but will not predict an absolute future.