Measure for Measure: Boston-Based Technical Toolkits for Measuring Walkability, Livability, Accessibility and Environmenta...
Livability Indicators Database October 21, 2011 SNEAPA Conference Providence, RI Sean Pfalzer Boston Region Metropolitan P...
Background <ul><li>Livability Program </li></ul><ul><ul><li>Livable Community Workshops </li></ul></ul><ul><ul><li>Regiona...
Factors to Consider <ul><li>What is livability? </li></ul><ul><ul><li>Livability is local  </li></ul></ul><ul><ul><li>Regi...
Livable Places across Community Types Regional Urban Center  Downtown Salem Inner Core  Coolidge Corner,  Brookline Maturi...
Aspects of Livability <ul><li>Is walking a viable option? </li></ul><ul><li>How important is an automobile to existing tra...
Developing Indicators <ul><li>What data are already available? </li></ul><ul><li>MassDOT Road Inventory </li></ul><ul><ul>...
Developing Indicators Demographics <ul><li>Population density </li></ul><ul><li>Employment density </li></ul>Walking <ul><...
Automobile Ownership per Household
Daily Vehicle-Miles Traveled per Household
 
Sidewalk Coverage
 
Miles of Bicycle Accommodations
Indicators of Livability across Community Types Community Type Community Population Density Employment Density Sidewalk Co...
Data Limitations <ul><li>Age of sidewalk data  </li></ul><ul><li>Speed of bicycle facility implementation </li></ul><ul><l...
Feedback <ul><li>Some disagreement over “livability” </li></ul><ul><li>Interest in more indicators </li></ul><ul><ul><li>T...
Next Steps <ul><li>Collect and incorporate new data </li></ul><ul><li>Update existing data </li></ul><ul><li>Use indicator...
More Information <ul><li>Sean Pfalzer </li></ul><ul><li>[email_address] </li></ul><ul><li>Livability Program Manager </li>...
Measuring Environmental Justice October 21, 2011 SNEAPA Conference Providence, RI Bruce L. Kaplan, AICP Boston Region Metr...
Environmental Justice Legislation <ul><li>Title VI of Civil Rights Act of 1964 </li></ul><ul><li>Executive Order 12898 (19...
What about Metrics? <ul><li>EJ focus is often on: </li></ul><ul><ul><li>Planning process of enfranchisement, outreach, goa...
Benefit-vs.-Burden Evaluation of Future Projects <ul><li>Few MPOs appear to have used future-year regional model results f...
Who Has Done It at Least Once?  <ul><li>Atlanta </li></ul><ul><li>Baltimore </li></ul><ul><li>Bay Area (MTC) </li></ul><ul...
Step 1:  Locating Residential Target Populations in the Study Area <ul><li>Identify  Cambridge, Medford, and Somerville Tr...
Recent Application by Boston Region MPO : Green Line Extension   EA
Performance Measures <ul><li>Accessibility to Jobs and Services </li></ul><ul><ul><li>Within a 20-minute  auto  or 40-minu...
Performance Measures <ul><li>Mobility, Congestion, and Environmental </li></ul><ul><ul><li>Average  highway  and  transit ...
Scenarios Studied <ul><li>2030 No-Build Scenario   </li></ul><ul><ul><li>Preferred Alternative for 2030 from Regional  Tra...
Transit Accessibility to Jobs   Using Unweighted Total Travel Times
Highway Accessibility to Jobs Using Unweighted Total Travel Times
Transit Accessibility to Services Using Unweighted Total Travel Times
Highway Accessibility to Services Using Unweighted Total Travel Times
Changes in Mobility Using Unweighted Total Travel Times
Changes in Congestion and Air Quality Using Unweighted Total Travel Times
Step 1 Again, but for Disability <ul><li>Identify Disability Population TAZs in Cambridge, Medford, and Somerville: </li><...
Disability TAZs
Transit Accessibility to Jobs Using Unweighted Total Travel Times
Highway Accessibility to Jobs Using Unweighted Total Travel Times
Transit Accessibility to Services Using Unweighted Total Travel Times
Highway Accessibility to Services Using Unweighted Total Travel Times
Changes in Mobility Using Unweighted Total Travel Times
Changes in Congestion and Air Quality Using Unweighted Total Travel Times
Summary of Findings <ul><li>In  all cases measured, Green Line Extension will benefit Environmental Justice TAZs and Disab...
Methodological Issues/Problems Specific to the CTPS Model <ul><li>Use of current target population geography and definitio...
General Methodological Issues/Problems <ul><li>Severe future demographic uncertainty </li></ul><ul><li>Getting around the ...
Further Thoughts <ul><li>Increased dialogue needed across the planning profession: between modelers/GIS analysts and other...
Further Thoughts <ul><li>Room for methodological refinement </li></ul><ul><li>Room for expansion of slate of performance m...
Contact Information <ul><li>Bruce L. Kaplan </li></ul><ul><li>[email_address] </li></ul><ul><li>Principal Transportation P...
Measuring Livability Benefits  through Accessibility-Based Modeling October 21, 2011  SNEAPA  Conference Caroline Ducas, E...
Overview <ul><li>Motivation </li></ul><ul><li>Overview of research objectives </li></ul><ul><li>Concepts of accessibility ...
Motivation <ul><ul><li>US DOT’s announcement of the “Livability Initiative” has prompted FTA to reassess how it evaluates ...
Objectives <ul><ul><li>Can accessibility measures be used as a meaningful and effective metric to capture and evaluate som...
Livability <ul><li>“ Where if people don’t want an automobile, they don’t  have to have one.  A community where you can wa...
Accessibility <ul><li>Accessibility is the “extent to which land use and transport systems enable (groups of ) individuals...
Accessibility Measure Criteria <ul><li>Ideal measures for project evaluation purposes are: </li></ul><ul><ul><ul><li>Theor...
Context: MBTA Green Line Extension
Context: MBTA Green Line Extension
Accessibility Model Development <ul><li>Transportation model, developed in CUBE Voyager, includes the following trip types...
Isochrone Measures <ul><li>A i  = ∑ j  O j  W j </li></ul><ul><li>Where: </li></ul><ul><li>  i = origin location </li></ul...
Isochrone Model Assumptions <ul><li>MIT academic model, 2030 no-build and GLX build scenarios </li></ul><ul><li>Thresholds...
Isochrone Model Assumptions
Gravity Measures <ul><li>A i  = ∑ j  O j  f(C ij ) </li></ul><ul><li>Where: </li></ul><ul><li>  i = origin location </li><...
<ul><li>MIT academic model, 2030 no-build and GLX build scenarios </li></ul><ul><li>Gravity function describing aversion t...
Example of Gravity Function :  Access to Employment
Isochrone Employment Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Gravity Employment Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Isochrone Shopping Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Gravity Shopping Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Isochrone Health Care Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Gravity Health Care Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Isochrone Recreation Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Gravity Recreation Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
Isochrone Education Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index Tufts Tufts
Isochrone Education Accessibility: Isochrone time threshold increased by 10 minutes No-build Scenario Build Scenario LEGEN...
Gravity Education Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index Tufts Tufts
Results and Analysis <ul><li>Both isochrone and gravity measures show increases in accessibility to key opportunities betw...
Summary  <ul><li>Accessibility is a key, non-negotiable, comprehensible, and quantifiable component of livability </li></u...
Contact Information <ul><li>Caroline Ducas </li></ul><ul><li>[email_address] </li></ul><ul><li>Transportation Engineer & P...
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Measure for Measure: Boston-based Technical Toolkits for Measuring Walkability, Livability, Accessibility, and Environmental Justice

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  • Would be good for “Bicycle coverage” to have word(s) added that would refer to the type(s) of bicycle facilities being referred to. “Bicycle travel coverage (miles of facilities)”?
  • In presenting, make sure to make clear right away that each dot represents an individual Boston-region municipality (or neighborhood of the inner core?)
  • Before now you’ve been listing the four community types in the order that’s the reverse of this order.
  • Be sure to talk about why more cities near the beginning of the alphabet have been doing it.
  • I advocate lower-casing the names of the two types of TAZ, though this instance isn’t quite as bad as in the earlier instance of caps.
  • Capitalizing “Disability” and “Burden”: I strongly believe that this gives a very bad impression.
  • Change “to” to “of” I’ve e-mailed Karl about including CTPS.
  • Though I’m not familiar with the terms in the last two bullets, I highly doubt they should be capitalized. Like “intelligent transportation systems” shouldn’t be.
  • Route not Routes Station not Stations
  • Measure for Measure: Boston-based Technical Toolkits for Measuring Walkability, Livability, Accessibility, and Environmental Justice

    1. 1. Measure for Measure: Boston-Based Technical Toolkits for Measuring Walkability, Livability, Accessibility and Environmental Justice Sean Pfalzer, Boston Region MPO Bruce Kaplan, Boston Region MPO Caroline Ducas, Parsons Brinckerhoff
    2. 2. Livability Indicators Database October 21, 2011 SNEAPA Conference Providence, RI Sean Pfalzer Boston Region Metropolitan Planning Organization
    3. 3. Background <ul><li>Livability Program </li></ul><ul><ul><li>Livable Community Workshops </li></ul></ul><ul><ul><li>Regional Forums </li></ul></ul><ul><ul><li>Online Resources - Livability Indicators Database </li></ul></ul><ul><li>Objectives </li></ul><ul><ul><li>Raise awareness </li></ul></ul><ul><ul><li>Facilitate local discussion </li></ul></ul><ul><ul><li>Identify strategies </li></ul></ul>
    4. 4. Factors to Consider <ul><li>What is livability? </li></ul><ul><ul><li>Livability is local </li></ul></ul><ul><ul><li>Region is diverse </li></ul></ul><ul><li>Community Types </li></ul><ul><ul><li>Inner Core </li></ul></ul><ul><ul><li>Regional Urban Center </li></ul></ul><ul><ul><li>Maturing Suburb </li></ul></ul><ul><ul><li>Developing Suburb </li></ul></ul>
    5. 5. Livable Places across Community Types Regional Urban Center Downtown Salem Inner Core Coolidge Corner, Brookline Maturing Suburb Minuteman Trail, Lexington Developing Suburb Commuter Rail Station, Ipswich
    6. 6. Aspects of Livability <ul><li>Is walking a viable option? </li></ul><ul><li>How important is an automobile to existing travel patterns? </li></ul><ul><li>Are there on-road or off-road facilities for bicyclists? </li></ul><ul><li>How safe is it for bicyclists and pedestrians? </li></ul><ul><li>Are there nearby employment opportunities? </li></ul>
    7. 7. Developing Indicators <ul><li>What data are already available? </li></ul><ul><li>MassDOT Road Inventory </li></ul><ul><ul><li>Miles of sidewalks and bicycle accommodations </li></ul></ul><ul><ul><li>Miles of roadway </li></ul></ul><ul><li>RMV Inspection Records (MassGIS and MAPC) </li></ul><ul><ul><li>Passenger vehicle miles traveled (VMT) </li></ul></ul><ul><ul><li>Automobile ownership </li></ul></ul><ul><li>RMV Crash Reports </li></ul><ul><ul><li>Pedestrian and bicyclist crashes </li></ul></ul>
    8. 8. Developing Indicators Demographics <ul><li>Population density </li></ul><ul><li>Employment density </li></ul>Walking <ul><li>Sidewalk coverage </li></ul><ul><li>Resident walk share </li></ul>Bicycling <ul><li>Bicycle coverage </li></ul><ul><li>Resident bike share </li></ul>Automobile Usage <ul><li>Automobiles per household </li></ul><ul><li>VMT per household </li></ul>Public Health and Safety <ul><li>Bicycle crash rate (per 1,000 residents) </li></ul><ul><li>Pedestrian crash rate (per 1,000 residents) </li></ul>
    9. 9. Automobile Ownership per Household
    10. 10. Daily Vehicle-Miles Traveled per Household
    11. 12. Sidewalk Coverage
    12. 14. Miles of Bicycle Accommodations
    13. 15. Indicators of Livability across Community Types Community Type Community Population Density Employment Density Sidewalk Coverage Bicycle Coverage Autos per HH Daily VMT per HH Inner Core Somerville 18,436 5,027 90% 3.5% 1.1 29 Melrose 5,690 1,349 70% 0.9% 1.5 44 Regional Urban Center Salem 5,091 2,290 77% 2.2% 1.3 36 Framingham 2,583 1,761 49% 3.0% 1.7 53 Maturing Suburb Stoneham 3,492 1,274 58% 1.7% 1.7 49 Burlington 2,115 3,181 22% 0.0% 2.1 64 Developing Suburb Hudson 1,703 862 45% 2.1% 2.0 66 Bellingham 859 294 32% 2.2% 2.2 80
    14. 16. Data Limitations <ul><li>Age of sidewalk data </li></ul><ul><li>Speed of bicycle facility implementation </li></ul><ul><li>Underreported crashes </li></ul><ul><li>Sample size issues </li></ul><ul><li>Town-level measurement may blur data </li></ul><ul><li>Lack of level-of-service rating system for bicycle and pedestrian facilities </li></ul>
    15. 17. Feedback <ul><li>Some disagreement over “livability” </li></ul><ul><li>Interest in more indicators </li></ul><ul><ul><li>Transit coverage </li></ul></ul><ul><ul><li>VMT within community </li></ul></ul><ul><ul><li>Air quality </li></ul></ul><ul><li>Desire for finer detail </li></ul>
    16. 18. Next Steps <ul><li>Collect and incorporate new data </li></ul><ul><li>Update existing data </li></ul><ul><li>Use indicators as baseline for performance measures </li></ul>
    17. 19. More Information <ul><li>Sean Pfalzer </li></ul><ul><li>[email_address] </li></ul><ul><li>Livability Program Manager </li></ul><ul><li>Boston Region MPO Livability Program </li></ul><ul><li>www.bostonmpo.org/livability </li></ul>
    18. 20. Measuring Environmental Justice October 21, 2011 SNEAPA Conference Providence, RI Bruce L. Kaplan, AICP Boston Region Metropolitan Planning Organization
    19. 21. Environmental Justice Legislation <ul><li>Title VI of Civil Rights Act of 1964 </li></ul><ul><li>Executive Order 12898 (1994) </li></ul><ul><ul><li>Identify and address disproportionately high and adverse human health or environmental effects on minority and low-income populations </li></ul></ul>
    20. 22. What about Metrics? <ul><li>EJ focus is often on: </li></ul><ul><ul><li>Planning process of enfranchisement, outreach, goal setting, definitions, needs assessment </li></ul></ul><ul><ul><li>Public participation </li></ul></ul><ul><ul><li>Current equity, not future equity </li></ul></ul><ul><ul><ul><li>Identifying communities of concern </li></ul></ul></ul><ul><ul><ul><li>Present-day problems and empirical data </li></ul></ul></ul><ul><ul><ul><li>The magic of GIS overlays </li></ul></ul></ul><ul><li>Evaluation of future projects not usually done </li></ul>
    21. 23. Benefit-vs.-Burden Evaluation of Future Projects <ul><li>Few MPOs appear to have used future-year regional model results for EJ evaluation </li></ul><ul><li>Mostly done at the level of the whole Regional Transportation Plan, not for individual projects </li></ul><ul><li>Yet there is a growing body of “how-to” literature </li></ul><ul><ul><li>NCHRP 8-36(11) (2002) </li></ul></ul><ul><ul><li>NCHRP 532 (2004) </li></ul></ul><ul><ul><li>EJ in Transportation Toolkit – www.brejtp.com </li></ul></ul>
    22. 24. Who Has Done It at Least Once? <ul><li>Atlanta </li></ul><ul><li>Baltimore </li></ul><ul><li>Bay Area (MTC) </li></ul><ul><li>Boston </li></ul><ul><li>Chicago </li></ul><ul><li>Columbus, OH </li></ul><ul><li>Hartford </li></ul><ul><li>Greater LA (SCAG) </li></ul><ul><li>Milwaukee </li></ul><ul><li>Seattle </li></ul><ul><li>San Antonio </li></ul><ul><li>Washington, DC </li></ul>
    23. 25. Step 1: Locating Residential Target Populations in the Study Area <ul><li>Identify Cambridge, Medford, and Somerville Transportation Analysis Zones (TAZs) that are low income or minority: </li></ul><ul><ul><li>Low income – Median household income at or below 80% of the 2000 MPO median ($44,640) </li></ul></ul><ul><ul><li>Minority – Minority population share greater than the 2000 MPO average (21.4%) </li></ul></ul>
    24. 26. Recent Application by Boston Region MPO : Green Line Extension EA
    25. 27. Performance Measures <ul><li>Accessibility to Jobs and Services </li></ul><ul><ul><li>Within a 20-minute auto or 40-minute transit trip (unweighted travel times) : </li></ul></ul><ul><ul><ul><li>Basic, retail, and service employment </li></ul></ul></ul><ul><ul><ul><li>Health care and higher education </li></ul></ul></ul><ul><ul><ul><li>Averaged by number of TAZs in each category </li></ul></ul></ul><ul><ul><li>Average unweighted travel times to accessible jobs and services </li></ul></ul>
    26. 28. Performance Measures <ul><li>Mobility, Congestion, and Environmental </li></ul><ul><ul><li>Average highway and transit door-to-door unweighted travel times for trips Produced in and Attracted to TAZ </li></ul></ul><ul><ul><li>Vehicle-Miles Traveled (VMT) per square mile </li></ul></ul><ul><ul><li>CO emissions per square mile </li></ul></ul>
    27. 29. Scenarios Studied <ul><li>2030 No-Build Scenario </li></ul><ul><ul><li>Preferred Alternative for 2030 from Regional Transportation Plan without Green Line Extension </li></ul></ul><ul><li>Representative 2030 Build Scenario </li></ul><ul><ul><li>2030 No-Build Scenario with D Branch extended to College Avenue and E Branch extended to Union Square </li></ul></ul>
    28. 30. Transit Accessibility to Jobs Using Unweighted Total Travel Times
    29. 31. Highway Accessibility to Jobs Using Unweighted Total Travel Times
    30. 32. Transit Accessibility to Services Using Unweighted Total Travel Times
    31. 33. Highway Accessibility to Services Using Unweighted Total Travel Times
    32. 34. Changes in Mobility Using Unweighted Total Travel Times
    33. 35. Changes in Congestion and Air Quality Using Unweighted Total Travel Times
    34. 36. Step 1 Again, but for Disability <ul><li>Identify Disability Population TAZs in Cambridge, Medford, and Somerville: </li></ul><ul><li>TAZs in which the percentage of population with a disability (persons over 5 yrs. old reporting themselves as having a disability) is greater than the eastern Massachusetts average (17.6%). </li></ul>
    35. 37. Disability TAZs
    36. 38. Transit Accessibility to Jobs Using Unweighted Total Travel Times
    37. 39. Highway Accessibility to Jobs Using Unweighted Total Travel Times
    38. 40. Transit Accessibility to Services Using Unweighted Total Travel Times
    39. 41. Highway Accessibility to Services Using Unweighted Total Travel Times
    40. 42. Changes in Mobility Using Unweighted Total Travel Times
    41. 43. Changes in Congestion and Air Quality Using Unweighted Total Travel Times
    42. 44. Summary of Findings <ul><li>In all cases measured, Green Line Extension will benefit Environmental Justice TAZs and Disability Population TAZs </li></ul><ul><li>In most cases measured, benefits are greater for the Environmental Justice and Disability Population TAZs than for other TAZs </li></ul>
    43. 45. Methodological Issues/Problems Specific to the CTPS Model <ul><li>Use of current target population geography and definitions for future assessment (for example, ethnicity stays constant) </li></ul><ul><li>TAZ / Census geography mismatches </li></ul><ul><li>TAZ weighting </li></ul><ul><li>Health care = hospital beds? </li></ul><ul><li>Income not a mode choice parameter </li></ul><ul><li>Mismatch between employment needs of low-income populations and “accessible” jobs </li></ul><ul><li>Room for expansion of air quality analysis </li></ul>
    44. 46. General Methodological Issues/Problems <ul><li>Severe future demographic uncertainty </li></ul><ul><li>Getting around the issue of using current-year definitions and geography for future-year work </li></ul><ul><li>EJ status - defined by residents or users? </li></ul><ul><li>Defining “disability” and/or other “non-EJ” communities of concern </li></ul><ul><li>Difficulty associated with project/study area level vs. Regional Transportation Plan level </li></ul><ul><li>Weighted time vs. unweighted time vs. impedance </li></ul><ul><li>Benefit/burden threshold </li></ul>
    45. 47. Further Thoughts <ul><li>Increased dialogue needed across the planning profession: between modelers/GIS analysts and others involved in the EJ equity process/analysis </li></ul><ul><ul><li>Others unaware that quantitative measures, such as travel demand model outputs, are readily available and can be used for evaluation and assessment </li></ul></ul><ul><ul><li>Quantitative community needs to take proactive stance </li></ul></ul>
    46. 48. Further Thoughts <ul><li>Room for methodological refinement </li></ul><ul><li>Room for expansion of slate of performance measures </li></ul><ul><li>When quantitative work is done for EJ or other “community” equity analysis, make sure it sees the light of day and is incorporated into larger documents </li></ul>
    47. 49. Contact Information <ul><li>Bruce L. Kaplan </li></ul><ul><li>[email_address] </li></ul><ul><li>Principal Transportation Planner </li></ul><ul><li>Central Transportation Planning Staff </li></ul><ul><li>Staff to the Boston Region </li></ul><ul><li>Metropolitan Planning Organization </li></ul><ul><li>www.bostonmpo.org </li></ul>
    48. 50. Measuring Livability Benefits through Accessibility-Based Modeling October 21, 2011 SNEAPA Conference Caroline Ducas, EIT, Transportation Engineer & Planner
    49. 51. Overview <ul><li>Motivation </li></ul><ul><li>Overview of research objectives </li></ul><ul><li>Concepts of accessibility and livability </li></ul><ul><li>Accessibility model development </li></ul><ul><li>Results and analysis </li></ul><ul><li>Conclusions </li></ul>
    50. 52. Motivation <ul><ul><li>US DOT’s announcement of the “Livability Initiative” has prompted FTA to reassess how it evaluates transit project benefits in the New Starts project evaluation process </li></ul></ul><ul><ul><li>Tools that incorporate livability benefits are also needed on the local level to evaluate and potentially improve proposed project alternatives </li></ul></ul>
    51. 53. Objectives <ul><ul><li>Can accessibility measures be used as a meaningful and effective metric to capture and evaluate some of the livability benefits of transportation projects? </li></ul></ul><ul><ul><li>How should accessibility be measured? </li></ul></ul>
    52. 54. Livability <ul><li>“ Where if people don’t want an automobile, they don’t have to have one. A community where you can walk to work, your doctor’s appointment, pharmacy or grocery store. Or you could take light rail, a bus or ride a bike” </li></ul><ul><li> – Secretary Ray LaHood </li></ul>Photo Source: www.zimbio.com
    53. 55. Accessibility <ul><li>Accessibility is the “extent to which land use and transport systems enable (groups of ) individuals to reach activities or destinations.” </li></ul><ul><li> – Geurs and van Wee </li></ul>
    54. 56. Accessibility Measure Criteria <ul><li>Ideal measures for project evaluation purposes are: </li></ul><ul><ul><ul><li>Theoretically sound </li></ul></ul></ul><ul><ul><ul><li>Meaningful </li></ul></ul></ul><ul><ul><ul><li>Simple to compute with available data and technology </li></ul></ul></ul><ul><ul><ul><li>Easily communicated to non-technical audiences </li></ul></ul></ul><ul><ul><ul><li>Effective in enhancing the quality of proposed projects </li></ul></ul></ul><ul><ul><li>Accessibility measures that meet these criteria include: </li></ul></ul><ul><ul><ul><li>Isochrone Accessibility Measures </li></ul></ul></ul><ul><ul><ul><li>Gravity Accessibility Measures </li></ul></ul></ul>
    55. 57. Context: MBTA Green Line Extension
    56. 58. Context: MBTA Green Line Extension
    57. 59. Accessibility Model Development <ul><li>Transportation model, developed in CUBE Voyager, includes the following trip types used to evaluate key components of livability: </li></ul><ul><ul><li>Home-based work – access to employment </li></ul></ul><ul><ul><li>Home-based shopping – access to shopping </li></ul></ul><ul><ul><li>Home-based school – access to education </li></ul></ul><ul><ul><li>Home-based other – access to health care </li></ul></ul><ul><ul><li>Home-based recreation – access to recreation </li></ul></ul>
    58. 60. Isochrone Measures <ul><li>A i = ∑ j O j W j </li></ul><ul><li>Where: </li></ul><ul><li> i = origin location </li></ul><ul><li> j = destination location </li></ul><ul><li> A i = accessibility at location i </li></ul><ul><li> O j = number of opportunities at location j </li></ul><ul><li> W j = equals 1 if C ij <C* ij , and 0 otherwise </li></ul><ul><li> C ij = travel time (or distance or cost) from i to j </li></ul><ul><li>C* ij = given travel time (or distance or cost) threshold </li></ul>Considers the total number of opportunities an individual can reach within a given travel time threshold.
    59. 61. Isochrone Model Assumptions <ul><li>MIT academic model, 2030 no-build and GLX build scenarios </li></ul><ul><li>Thresholds defined using 90 th percentile of model trip length distribution </li></ul><ul><li>Travel times from time period with highest number of trips for particular purpose used </li></ul><ul><li>Using un-weighted walk, initial wait, transfer wait, and in-vehicle travel times </li></ul><ul><li>No penalty for transfers </li></ul><ul><li>Fares not included </li></ul>
    60. 62. Isochrone Model Assumptions
    61. 63. Gravity Measures <ul><li>A i = ∑ j O j f(C ij ) </li></ul><ul><li>Where: </li></ul><ul><li> i = origin location </li></ul><ul><li> j = destination location </li></ul><ul><li> A i = accessibility at location i </li></ul><ul><li> O j = number of opportunities at location j </li></ul><ul><li> C ij = travel time (or distance or cost) from i to j </li></ul><ul><li>f(C ij ) = travel time (or distance or cost) impedance function </li></ul>Accounts for all opportunities while considering that the attractiveness of an opportunity decreases as the cost of travel to the reach the opportunity increases.
    62. 64. <ul><li>MIT academic model, 2030 no-build and GLX build scenarios </li></ul><ul><li>Gravity function describing aversion to travel is estimated from the model trip length distributions </li></ul><ul><li>Using weighted walk, initial wait, transfer wait times </li></ul><ul><li>3.5-minute transfer penalty </li></ul><ul><li>Fares included </li></ul>Gravity Model Assumptions
    63. 65. Example of Gravity Function : Access to Employment
    64. 66. Isochrone Employment Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    65. 67. Gravity Employment Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    66. 68. Isochrone Shopping Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    67. 69. Gravity Shopping Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    68. 70. Isochrone Health Care Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    69. 71. Gravity Health Care Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    70. 72. Isochrone Recreation Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    71. 73. Gravity Recreation Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index
    72. 74. Isochrone Education Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index Tufts Tufts
    73. 75. Isochrone Education Accessibility: Isochrone time threshold increased by 10 minutes No-build Scenario Build Scenario LEGEND Accessibility Index Tufts Tufts
    74. 76. Gravity Education Accessibility No-build Scenario Build Scenario LEGEND Accessibility Index Tufts Tufts
    75. 77. Results and Analysis <ul><li>Both isochrone and gravity measures show increases in accessibility to key opportunities between the no-build and Green Line Extension build scenarios </li></ul><ul><li>The need to define a threshold for isochrone measures can lead to unexpected and potentially inaccurate conclusions – Gravity measures overcome this limitation </li></ul><ul><li>Comprehensive view of accessibility important when considering livability-based policy – especially considering the aging demographic </li></ul>Isochrone Education Accessibility Gravity Education Accessibility
    76. 78. Summary <ul><li>Accessibility is a key, non-negotiable, comprehensible, and quantifiable component of livability </li></ul><ul><li>As such, accessibility measures can be used as one building block for decision makers as they consider livability benefits in the project evaluation process </li></ul><ul><li>Valuing accessibility benefits can additionally encourage coordination between project sponsors and land use planners, ultimately enhancing the quality of proposed projects </li></ul>Photo Source: www.dot.gov
    77. 79. Contact Information <ul><li>Caroline Ducas </li></ul><ul><li>[email_address] </li></ul><ul><li>Transportation Engineer & Planner </li></ul><ul><li>Parsons Brinckerhoff </li></ul><ul><li>www.pbworld.com </li></ul>

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