Forecasting and Evaluating Network Growth
David LevinsonNorah Montes de OcaFeng Xie
Introduction
• Build empirically-based network growth prediction models that address the questions:
• Will “business as usual” network construction decision rules produce desirable networks?
• Will new decision rules produce improved networks?• Should policies be changed to direct future network growth in a better direction?
• Should policies be changed to produce networks that will generate the best performance measures?
• Results would let decision makers see how current investment decision rules impact or limit future choices.
Movie
If They Come, Will You Build It?
The Base-year Network
(T0=1990)Trip Generation
Shortest Path Finding
Trip Distribution
SUE Traffic Assignment
Calculating MOEs
Ranking by jurisdictions
Investing by jurisdictions
Updating TAZ information
Travel Demand Forecasting Models
Updating Network Capacity, Hierarchy,
Topology
Investment Models
Budget Models
T=T+5
SONG 2.0 Flowchart
Flowchart of Investment Models
State/County Budget Models
• State budget model is estimated by regressing expenditures on state trunk highways by Mn/DOT or Met Council from 2000 to 2004 on statewide VKT and population. ($0.006/vkt)
• County budget model is estimated by regressing expenditures on county state-aid highways and county roads in 1990, 1995, 2000, and 2003 on county statistics such as VKT and #households.
Cost Model• From Levinson and Karamalaputi (2003).
MethodologyMethodology• Face to face interviews
* Using open-ended questions
• Who was interviewed?* Minnesota Department of Transportation- Program Management Department* Metropolitan Council-Planning Management
Department* Metro Area Managers* County Engineers and staff* City - Capital and Management Department
Questionnaire• Procedure for a project to
be approved for construction?
• Most important policies to look at when making decisions?
• Main criteria?• Performance measures
considered?• Ranking system existence?• Changes in criteria from
the past to actual?• Informal procedures?• Role of politicians in the
decision-making process?
Processes
Formal
* Structured process* Ranking system through point allocation* Task forces-committees
Informal
* Priorities•safety,preservation, capacity, •social and economic impacts, •community and agency involvement•Benefit/cost ratio, etc.
* No Ranking System
Informal ProcessesJurisdictions priorities and decision making:
•“ benefit/cost ratio > 1”•“ AADT > 15,000 on 3-lane roadways” (safety reasons)•“ Intersection volumes up to 7,500 vehicles per day”
•“Implementation of policy, strategy and investment level”•“Project development time”•“Most beneficial project for the system”•“Matching funds from local jurisdictions”
Formal Processes
1. Reduction in SOV trips and/or VMT 0-75 0-100 2. Reduction of vehicle emissions 0-100 0-150 3. Measure of project effectiveness 0-300 0-300B. Congestion Mitigation 200 350 1. Congestion/increase hourly person reduction 0-100 0-175 2. Traffic congestion reduction 0-100 0-175C. Service Efficiency and productivity 250 - 1. Service efficiency 0-125 -
2. Productivity 0-125 -
D. Regional Transit Priorities 300 - 1. Corridor priority (as ranked in 2030 TPP) 0-100 - 2. Location Suitability & Market Area Demand 0-100 - 3. Integration with existing Infrastructure 0-100 -
E. Development Framework Implementation 200 200
1. Employment, housing and transportation integration 0-200 0-200
a) Intensity 60 75
b) Linkages 60 75
c) Brownfields & Natural Resources 40 50
d) Affordable/Life Cycle housing 40 -
F. Maturity of project concept 100 100
TOTAL 1,525 1,200
A. Reduction in carbon monoxide (CO), nitrogen oxide (Nox), and volatile organic compound (VOC) emissions
475 550
Transit expansion
Demand or System
Management
Project ID NumberPoints
Project PriorityLevel of NeedCritical 51-60Significant 41-50Important 21-40Desirable 0-20
In adopted Five Year Plan2006 302007-2009 202010 10New for 2006-2009 0
Integrated Project 10
Sub-Total Project Priority
Contributions to City Goals/Objs:Strong Contribution 46-70Moderate Contribution 16-45Little or No Contribution 0-15
Operating Costs: -25 to +25'
Sub-total Goals & Operating Costs
Qualitative Criteria:Neighborhood Livability & Safety 0-15Public benefit 0-15Capital Cost/Customer Service Delivery 0-15Environmental Quality 0-15Collaboration & Leveraging 0-15Effect on Tax Base & Job Creation 0-15Intellectual & Cultural Implications 0-15
Sub-Total Qualitative
Total Rating Points300
PossibleSource: Capital Long Range Improvement Committee. 2005 Capital Guidelines
CLIC Rating form
PERFORMANCE MEASUREPOINTSCapacity V/C ratio 100
Pavement 100
Safety 100
Municipal support 100
DETAILS
for example:
Pavement quality indexRatio of project crash rate to county average
=(ADDT X 0.10)/Capacity
City council resolution supports ISTEA application…………………………………….…………50City staff gives verbal support for project…..…………20
City approves preliminary design and commits to cost share greater than required by county policy………………………………………………..…..100
>5=100 points, >3=90, >20=80…<.50=0
Ratio of 10% AADT to current capacity
AADT=11900Current capacity/hr=1200Ratio=0.99Normalized score=651.52 = 100 points0.67 = 44 pointsPavement Condition IndexPresent Service-ability rating rideability
A. Relative Importance of the route 0-100 0-100 0-100 0-150 0-100B. Deficiencies and Solutions on category 425 425 425 375 425 1. Crash reduction - 0-150 0-150 0-100 0-150 On principal Arterial 0-50 - - - - On the reliever 0-50 - - - - 2. Access Management 0-125 0-175 0-125 0-125 0-175
3. Air Quality 0-100 0-50good
movement 0-75
0-100 0-50
4. Congestion Reduction - 0-50shoulder
improvement 0-75
0-50 0-50
On principal Arterial 0-50 - - - - On the reliever 0-50 - - - -C. Cost Effectiveness 275 275 275 275 275 1. Crash reduction 0-125 0-125 0-125 0-125 0-125
2. Congestion Reduction 0-75 0-75good
movement 0-75
0-75 0-75
3. Air Quality 0-75 0-75shoulder
improvement 0-75
0-75 0-75
D. Development Framework Implementation 300 300 300 300 300 1. Employment, housing and transportation integration0-200 0-200 0-200 0-200 0-200 a) Intensity 60 60 60 60 60 b) Linkages 60 60 60 60 60 c) Brownfields & Natural Resources 40 40 40 40 40 d) Affordable/Life Cycle housing 40 40 40 40 40 2. Integration of modes 0-100 0-100 0-100 0-100 0-100E. Maturity of project concept 0-100 0-100 0-100 0-100 0-100
TOTAL 1,200 1,200 1,200 1,200 1,200
Non-freeway Principal Arterial
Reliever ExpanderConnectorAugmenter
Flowcharts-Informal processesRoadways under
County’s jurisdiction
Project solicitation
ADT>15,000
3 lane-roads
Scott County
Application review
SafetyAverage Daily Traffic (ADT)
Project intop 200
high crash location list
Project approval
Reapplication?
Project construction
End
yesyes
yes
nono
yes
no
no
Flowcharts - Formal Processes - CityMinneapolis streets
Project solicitation
City of Minneapolis
Application review
Reapplication?
End
Compute scores
Highest scored project selection
Allocation of funding availability
Project approval
Project construction
yes
no no
yes
Coded Decision Rules • Flowcharts that describe the decision-making process of jurisdictions with regard to road investment• Coded if-then rules of each jurisdiction• Rules of continuous scores that ensure a project gets a unique score from a jurisdiction
• Example://ORIGINAL RULE:if(AADT>30000)juris_score[1][i]+=50;//if(AADT >20000)juris_score[1][i]+=38;//else if (AADT >10000)juris_score[1][i]+=25;
if(adt>30000)juris_score[1][i]+=Math.min(50,38+(50-38)*(AADT -30000)/(100000-30000));else if(adt>20000)juris_score[1][i]+=25+(38-25)*(AADT -20000)/(30000-20000);else if (adt>10000)juris_score[1][i]+=0+(25-0)*(AADT -10000)/(20000-10000);
Legacy Links
Constraints
Scenario Expansion Decision Rules
New Construction Decision Rules
Total Budget
Expansion Construction Budget Split
New Link Choice Set
1 Stated Revealed Standard 50/50 Legacy 2 Most
structured Revealed Standard 50/50 Legacy
3 Least structured
Revealed Standard 50/50 Legacy
4 Stated Revealed Scenarios 50/50 Legacy 5 Stated Revealed Standard 25/75 Legacy 6 Revealed Revealed Standard 50/50 Legacy 7 Revealed Revealed Standard 50/50 All
potential
Scenarios Tested
Scenario 1.
Baseline - State
Scenario 4.
Budget Increase400% - State
Scenario 6. LK
(legacy links) Model - State
Scenario 7. LK (new
choice set)
Model - State
State - Link Expansion
0.00
100.00
200.00
300.00
400.00
500.00
600.00
2005 2010 2015 2020 2025 2030 Year
Lane kilometer
Scenario 1. Baseline Scenario 3. Least Structured Scenario 4c. Increase400
Scenario 4e. Decrease25 Scenario 6. LK-Expansion Scenario 7. LK-New Construction
State Link Expansion
MOE: VKTMeasure of Effectiveness : Vehicle Kilometer Travel
-300
-200
-100
0
100
200
300
400
2005 2010 2015 2020 2025 2030
in Millions
Year
Differences
Scenario 2 - Scenario 1 Scenario 3 - Scenario 1 Scenario 4c - Scenario 1
Scenario 5 - Scenario 1 Scenario 6 - Scenario 1 Scenario 7 - Scenario 1
MOE: VHT
Measure of Effectiveness : Vehicle Hour Travel
-400
-300
-200
-100
0
100
200
300
400
500
2005 2010 2015 2020 2025 2030
in Millions
Year
Difererences
Scenario 2 - Scenario 1 Scenario 3 - Scenario 1 Scenario 4c - Scenario 1
Scenario 5 - Scenario 1 Scenario 6 - Scenario 1 Scenario 7 - Scenario 1
General Conclusions• Perception gap on
decision making process.• References to official
documents about safety, capacity, pavement conditions, and so on, but not a clear answer.
• In the past, projects selected on the engineer’s perception. However, safety issues, road conditions and capacity were present in the engineer’s minds.
• Levels of government with no ranking system - main criterion based on performance measures.
• Safety-most important.
• Counties containing Metropolitan Area center have a more formal decision-making process and a ranking system.
Conclusions-continued• Mn/DOT has backed away from
a formal process as described in the 1997 Transportation System Plan. Now more informal, less quantitative process = Decrement in transparency.
• At State level the biggest concern is what every day transportation system user notices = level of congestion and a comfortable ride.
• Some jurisdictions declined to endorse flowcharts presented, not providing alternatives.Main reason………….political & community concern
• As budget rises:• VKT rises• Network expands• Accessibility increases
• Users spend less time on the road
• VHT declines
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