Forecasting and Evaluating Network Growth David Levinson Norah Montes de Oca Feng 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 (T 0 =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).

Methodology 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 Processes Jurisdictions 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

Flowcharts- Informal processes Roadways under County’s jurisdiction Project solicitation ADT>15, lane-roads Scott County Application review Safety Average Daily Traffic (ADT) Project in top 200 high crash location list Project approval Reapplicatio n? Project construction End yes no yes no

Flowcharts - Formal Processes - City Minneapolis streets Project solicitation City of Minneapolis Application review Reapplicatio n? End Compute scores Highest scored project selection Allocation of funding availability Project approval Project construction yes 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 )/( )); else if(adt>20000)juris_score[1][i]+=25+(38-25)*(AADT )/( ); else if (adt>10000)juris_score[1][i]+=0+(25-0)*(AADT )/( );

Legacy Links

Constraints

Scenarios Tested

Scenario 1. Baseline - State

Scenario 4. Budget Increase 400% - State

Scenario 6. LK (legacy links) Model - State

Scenario 7. LK (new choice set) Model - State

State Link Expansion

MOE: VKT

MOE: VHT

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