2009 Minnesota MPO Conference August 11, 2009 Incorporating Uncertainty of Inputs in Travel Demand Modeling Activities 2009 Minnesota MPO Conference August 11, 2009 2/22/2019

Presentation Objectives Clarify what we mean by “uncertainty” Identify key drivers of uncertainty Highlight examples from others Discuss possible options for strengthening Minnesota modeling practices, including opportunities, constraints and challenges 2/22/2019

Special Report 288 Metropolitan Travel Forecasting Inherent Weaknesses of the Models… “Poor representation of uncertainty is another deficiency. Most travel forecasting models produce a single answer, although the model is estimated, calibrated, and validated on the basis of data sets subject to sampling and other errors.” TRB 2007, page 85 2/22/2019

Terms and Distinctions Modeling Bias Measurement or sampling errors Specification errors Uncertainty Variable and conflicting views and assumptions about the future “With careful planning we can minimize bias, but uncertainty in the estimates will always be there and often times this uncertainty is not recognized or even quantified.” – Steve Ruegg, Parsons Brinckerhoff 2/22/2019

Factors Contributing to Uncertainty Traffic and VMT estimates Land use Population Household numbers and changes in composition Economic activities, including employment/job numbers and locations Funding and the timing of related system improvements Mode usage Transportation related policies 2/22/2019

Trends in VMT, Population, Labor Force, Households and Employment 2/22/2019

Municipal Boundary Adjustments 2/22/2019

Total VMT Growth on All Roads in Minnesota 1992-2008 2/22/2019

Total Population Growth 1992-2008 2/22/2019

Total Percent Employment Growth 1992-2008 2/22/2019

County Level VMT and Socio-Economic Trends 2/22/2019

County Level VMT and Socio-Economic Trends 2/22/2019

County Level VMT and Socio-Economic Trends 2/22/2019

Past Errors in State Demographic Center Projections of Population Mpls/StP Area 2/22/2019

Updating the Metro Profile From an April, 2008 memo to the Transportation Technical Committee (Metro COG projections include building permits issued) 2/22/2019

Incorporating Uncertainty – What the Experts Say…. Utilize the most robust data available Consider the sources of uncertainty and qualitatively assess the probability and/or likelihood of variability Establish a range of alternative scenarios or sensitivity tests around data inputs that have significant variability 2/22/2019

The Land Use Scenario DevelopeR (LUSDR) – Oregon DOT “LUSDR was developed as a stochastic microsimulation to facilitate the automatic generation of multiple scenarios subject to general specifications of subject to general specifications of potential urban reserve areas. The governments in the metropolitan area identified areas that they would like to include within urban reserve areas and the general mix of uses (residential, commercial industrial) that they would like to achieve. This inventory was treated as a future land supply and LUSDR was then run several dozen times to produce scenarios that vary in the arrangement of land uses but are all consistent with the regional inputs, land use designations and development location behavior. The scenarios show the variety of ways that growth might occur if lands were made available as proposed. The regional transportation model was run for each of these scenarios to compare the transportation effects.” http://www.oregon.gov/ODOT/TD/TPAU/docs/M_Ladn/LUSDR.pdf 2/22/2019

FTA Examples – Ken Cervenka To promote transparency FTA now requires: Documentation of capital-cost and rider uncertainties Use of ranges in forecast estimates Documentation of critical assumptions and significant sources of uncertainty Exploration of alternative outcomes, likelihoods and implications, even those outside of modeled behaviors or current experiences Engaging decision makers in risk analysis and accuracy discussions 2/22/2019

Honolulu Rail Project Example Source of Uncertainty Lower Bound Best Estimate Upper Bound Western End Employment Increased Job Growth Current Plan 2017 Distribution Pattern 2030 Highway Investments 2030 Highway Investment Plan More Modest Investment Plan No Improvements Bus Restructuring Revisions Revise Top Ten Routes Revise Top Five Routes Existing Bus Plan Fixed Guideway Service Levels 5 Minute Peak 10 Minute Off-Peak 3 Minute Peak 6 Minute Off-Peak -- 2/22/2019

Department of Transport United Kingdom – April 2009 Provide a systematic analysis method for dealing with uncertainty Create an uncertainty log to track: All the local and external uncertainties and factors likely to affect traffic, patronage, revenues, etc. The current status of each of these factors and the anticipated probability of uncertainty Invite wide consultation on to promote consensus on the assessment of uncertainty Use the uncertainty log to define a “core” scenario and alternative scenarios for describing the future Report findings and educate decision makers, the public and affected stakeholders to think of a range of options 2/22/2019

Group Discussion Given current trends and uncertainties…. How are others here today using risk assessments in their work? What are some possible options for strengthening modeling in Minnesota? What opportunities, challenges and constraints do we need to consider as we move forward? What are some possible next steps? 2/22/2019

Uncertainty in Socioeconomic Forecasting -- Todd Graham, Metropolitan Council 2/22/2019