Cristina Scarlat

Northwest Arkansas

Regional Planning Commission

ASCE - 2017 Day of Training March 16, 2017

0 The Northwest Arkansas Regional Travel Forecasting Model is a regional model based on the traditional four-step sequential modeling method with a feedback loop.

0 The model uses Caliper’s TransCAD software to run, peak-period modeling is incorporated through time of day (TOD) models

0 A 2004 Household Travel Behavior Study was analyzed to derive trip generation rates, trip length frequency distributions, time-of day distributions and vehicle occupancy rates

NWARPC Model History

0 In 2004 NWARPC and AHTD contracted Bernardin, Lochmueller and Associates, Inc. (BLA) in cooperation with Alliance Transportation Group (ATG) and MOREPACE to develop the Northwest Arkansas Regional Travel Demand Model. NWARPC was an active project participant involved from the beginning in data collection and development.

0 Model Base Year: 2005

0 Forecast Years: 2010, 2015, 2030

0 Between 2007-2010 NWARPC maintained the model in-house with continuous updates to the network, TAZs, socio-economic data, land-use, etc. and used it for projects prioritization, scenarios and, most importantly, the Long Range Plan and Transportation Improvements Plans.

0 In 2010 NWARPC contracted Parsons Brinckerhoff (PB) to conduct the Northwest Arkansas Western Beltway Feasibility Study, that included major upgrades to the model.

0 Model Base Year: 2005

0 Forecast Years: 2010, 2015, 2035

0 Improvements: Update the TransCAD Code to 5.0, Updated Interface and File Management, Updated Census Population data, Incorporated McDonald County, MO in the study area, Developed Corridor Alternatives, Developed Freight Traffic Analysis, Build vs No-Build scenarios for Western Beltway 2035 scenarios.

NWARPC Model History

0 In 2012 NWARPC contracted URS, Corporation in cooperation with Alliance Transportation Group (ATG) to develop the Northwest Arkansas Alternative Transportation Analysis. The model was utilized to estimate transit ridership for each proposed transit mode. 0 Model Base Year: 2005 0 Forecast Years: 2010, 2035

0 In 2014 NWARPC selected Parsons Brinckerhoff (PB) to conduct the Northwest Arkansas Travel Demand Model Upgrade/Transit that will include major upgrades to the model: 0 Model Base Year: 2010 0 Validation/Calibration of the new base year 0 Forecast Years: 2020, 2030, 2040 0 Develop the mode choice model 0 Add new geography (portion of Missouri that is now part of the TMA) 0 Develop Master network and TAZ layers that can be used for scenario and

forecast years 0 Develop a better Special Generator 0 Reconfigure the GISDK code to current industry standards 0 Create a blue-print for future model development and improvements

NWARPC Model History

What is a Travel Forecasting Model?

0 Mathematical expressions that are used to replicate the movement of people and vehicles within a transportation system

0 Basic Model – 4-step model

0 Trip Generation

0 Trip Distribution

0 Mode Choice

0 Network Assignment

Model Steps 0 Trip Generation

0 Based on observed rates – number of trips/HH

0 Done at HH level, by category (High/Low income HH)

0 Trip Distribution

0 Based on “gravity” model (attraction is proportional to size and inversely proportional to distance)

0 Done at Trip level, by purpose

Model Steps 0 Mode Choice

0 Based on probabilities

0 Done at Trip level, by category (auto/transit)

0 Considers details about the mode options

0 Assignment (what path to use to get there) 0 Based on “User Equilibrium” – the paths chosen will

change as algorithm runs, shortest path (congested) paths will be chosen such that no one can improve their travel time by selecting a different path

0 Done at Vehicle Level

Model Steps Before the Upgrade Model Steps After the Upgrade

0 Skims – Calculation of travel times and cost between origin and destination zones using the various modes of transportation.

0 Household Generation - The Population synthesizer generates synthetic households i with attributes xi to match total counts and TAZ average characteristics xa.

0 Trip Generation - Trip Generation calculates Pip, the decimal number of trips of each purpose produced by each household. It does this via regression models estimated on data collected in a 2005 household travel survey.

0 Trip Distribution - Trip Distribution aggregates the household trip productions by purpose and

by TAZ and calculates the trip attractions by purpose by TAZ. Productions (Ps) and Attractions (As)are matched up based on a gravity model whereby productions are pulled towards TAZs based on their number of attractions and the travel time from the production TAZ. The skims are used to determine travel times.

0 Mode Choice - The mode of travel for each PA pair is determined based on a logit model which takes the level of service characteristics, the household attributes and the cost of each mode into consideration. The skims are used to determine level of service and cost for each mode.

0 Time Of Day - The PA matrices are transformed into origin/destination pairs by time period (am

peak, pm peak, off-peak) based on observed percentages of daily traffic.

0 Assignment – The auto trips are assigned to the highway network and the transit trips are assigned to the transit network. Travel times and costs are re-calculated and are fed back to the trip distribution and mode choice steps. This feedback is done multiple times so that congested travel times are considered in the final set of choices.

For the current, updated model, the process is as follows:

Base Year vs. Forecast 0 We can look at roadways to understand travel behavior today,

but what about 5 years from now?

0 Why do households make trips?

0 Why do some households make more trips than others?

0 How far are people willing to drive to go to work? To school? To shop? Why?

0 Why do some people take the bus and others drive? Commuter Rail?

0 If given a choice, would people take a bus or get on light-rail? Why?

Base Year vs. Forecast

0 If we can identify and quantify the magnitude of the answers to the “why” we can develop a mathematical formula that allows us to “predict” what choices people will make.

0 We use survey data (Household survey, American Community Survey, Long-form of Census) to identify the whys and the magnitude of the whys.

Available Travel Behavior Sets

0 Census Transportation Planning Program (CTPP)

0 2005 Household (HH) Travel Survey (needs updating)

0 2010 On-Board Transit Passenger Survey (not quite adequate for the mode choice)

Available Travel Behavior Sets

0 Census Transportation Planning Program (CTPP) 0 Based on the annual American Community Survey

(ACS)- and the Longitudinal Employer-Household Dynamics (LEHD)

0 NWARPC used the CTPP 5-year tables (2007-2012)

A112106 - Household size (5) A112209 - Household size (5) by Number of workers in household (6)(Households) A112101 - Number of Persons under 18 (4) (Households) A112201 - Household income in the past 12 months (2010) (9) B112104 - Median Household income in the past 12 months (2010)(1) A112218C - Number of Workers in the household (6) by Household income in the past

12 months (2010$) (9) A112211 - Household size (5) by Vehicles available (6) (Households)

Available Travel Behavior Sets 0 2005 Household Travel Survey (needs updating)

0 In 2005 MORPACE International conducted a household travel survey

0 The household survey collected trip information for 675 households, containing 1,546 individuals who collectively made 6,209 trips.

0 Trip Purposes: 0 HBW - Home-based work

0 HBO - Home-based other

0 HBU - Home-based university/college

0 HBSC - Home-based school

0 HBSB - Home-based shopping/personal business

0 NHB - Non home-based (in the upgrade this category collapses the ‘NHBO‘ and ‘NHBW‘ trips from the original model).

Available Travel Behavior Sets 0 2010 On-Board Transit Passenger Survey (developed part of the

region’s Transit Development Plan) 0 Ridecheck report and on-board ridership survey of transit

passengers on ORT and Razorback Transit 0 Age 0 College Student (yes/no, UofA, NWACC, other) 0 Income range 0 Household size 0 Number of vehicles 0 Valid driver’s license

0 Ridecheck Survey – on 100% of ORT and RT fixed-route service – Boardings and Alightings (by stop, trip, route)

0 On-Board survey – for trip data (origin, destination, trip purpose) and demographics (age, gender, income, vehicle ownership, etc.)

0 Survey was not expanded but the ridecheck provided daily boardings by route at the time of the survey and was used to expand the survey and determine distribution of ridership across the transit sub-modes

Ridecheck Survey Counts

RT

ORT

Mode Choice Range of Choices

0 Non-Motorized (Active Transportation)

0 Walk

0 Bicycle

0 Private Auto

0 Drive Alone

0 Multiple Occupant

0 Toll/Non-Toll

0 HOV/Non-HOV

0 Managed Lane

0 Transit

0 Access Mode

0 Walk, PNR, KNR

0 Primary Transit Mode

0 Local Bus, BRT, UR, CR

0 Station Choice

0 Capacity, Crowding & Reliability

0 Benefit & Equity Analysis

Mode choice modes in the NWARPC Model

0 Vehicle 0 DA: Drive alone 0 SR2: Shared ride 2 0 SR3+: Shared ride 3+

0 Transit: There are three access nests, each with the transit modes listed under Walk. 0 Walk: walk-access transit

0 LB: Local bus (Ozark Transit) 0 RT: Razorback Transit, University of Arkansas 0 Additional modes can be added such as BRT, LR, Express Bus – currently none of those

modes exist in the region

0 PNR: park-and-ride 0 RT: Razorback Transit

0 KNR: “kiss-and-ride”/drop-off 0 RT: Razorback Transit

0 Non-Motorized 0 Bike 0 Walk

NWA Model Mode Choice

Los Angeles Mode Choice Model

21

Northwest Arkansas Travel Forecasting Model

0 Used for current and future forecasts

0 2040 Metropolitan Transportation Plan

0 Transportation Improvements Program (TIP) projects

0 Specific Scenarios

0 Future road projects plans

0 Transit routes planning and ridership estimates

*Years projections by the Arkansas Census State Data Center (CSDC) (2015) NWA Travel Forecasting Model

Model TAZs

2040 Model Network

Model Network

0 Master Network includes: 0 2010 Base Year

0 2020 Forecast Year

0 2030 Forecast Year

0 2040 Forecast Year

Network Validation

Observed Count Model Volume Difference Pct Difference % RMSE

Rural Interstate 1 8 79,000 62,850 -16,150 -20.4% 21.1%

Rural Principal Arterial 2 31 387,430 293,547 -93,883 -24.2% 29.4%

Rural Minor Arterial 6 54 349,550 305,948 -43,602 -12.5% 34.8%

Rural Major Collector 7 120 465,420 427,436 -37,984 -8.2% 63.3%

Rural Minor Collector 8 22 35,590 36,517 927 2.6% 108.3%

Rural Local 9 4 8,120 8,235 115 1.4% 24.6%

Urban Interstate 11 42 1,147,000 1,022,166 -124,834 -10.9% 15.1%

Urban Principal Arterial 14 197 3,414,070 3,404,172 -9,898 -0.3% 38.7%

Urban Minor Arterial 16 87 655,950 620,405 -35,545 -5.4% 42.4%

Urban Collector 17 159 746,320 610,527 -135,793 -18.2% 71.1%

Urban Local 19 6 29,590 29,579 -11 0.0% 61.6%

Off-Ramp 71 41 204,480 172,548 -31,932 -15.6% 43.8%

On-Ramp 72 44 215,160 184,611 -30,549 -14.2% 37.3%

Generic Ramp 75 5 51,700 47,562 -4,138 -8.0% 19.3%

Median Cross-Over 81 4 9,980 8,612 -1,368 -13.7% 23.4%

TOTAL 824 7,799,360 7,234,715 -564,645 -7.2%

Description

SUMMARY BY FACILITY TYPE

FHWA_FC # ObservationsVolume Comparison

Network Validation

Observed Count Model Volume Difference Pct Difference % RMSE

< 5000 1 401 1,379,450 857,143 -522,307 -37.9% 82.6%

5,000-10,000 2 165 1,310,460 1,168,610 -141,850 -10.8% 42.4%

10,000-20,000 3 156 2,323,950 2,178,764 -145,186 -6.2% 33.3%

20,000-30,000 4 55 1,327,500 1,362,360 34,860 2.6% 22.9%

30,000-40,000 5 40 1,227,000 1,336,207 109,207 8.9% 19.7%

40,000-50,000 6 5 174,000 216,560 42,560 24.5% 24.8%

> 50,000 7 2 57,000 115,071 58,071 101.9% 102.9%

TOTAL 824 7,799,360 7,234,715 -564,645 -7.2%

SUMMARY BY VOLUME GROUP

Volume Range Vol Range ID # ObservationsVolume Comparison

NWARPC Projected Population Density For 2040 by TAZ and

Arterial Roads (4 lanes and more)

NWARPC Projected Employment Density by TAZ

and Employment Centers with Over 1,000 Employees

(Infogroup Employment data – May 2015)

Employment Centers with over 1,000 Employees in the MPA and

Area Type by TAZ

How do Students get to UofA?

Average Travel Distance

Estimated Trip Length Frequency

2005 Survey

Model Scenario

Sain St. Connection

Sain St. Connection (Alt. 1)

Sain St. Connection (Alt. 2)

Sain St. Connection (Alt. 3)

Improving the NWARPC Model

0 Household Survey 0 Last survey was 2005 0 Quality sampling plan – all hh segments

0 On-board and Boarding to Alighting Survey 0 Quality sampling plan 0 Expandable in multiple dimensions 0 Full trip info

0 AirSage data for visitors and/or external model development

0 External Stations Counts and/or license plate survey 0 Capturing EI, IE, EE trips 0 Recalibrating the external models

Data Collection

0 Eliminate population synthesizer and the regression models for trip generation – replace with standard cross-classification (size, income, workers, autos) models 0 HBW trip rates by 5 segments (high/low sufficient,

high/low insufficient, zero cars).

0 HBO, HBSB, HBSC, HBU, NHBW, NHBO trip rates for all households or by income group perhaps

0 Replace the gravity-based trip distribution model with a logit-based destination choice model

0 More variables can be used to explain the observed choices

Existing Model Components

0 Mode Choice

0 Add new modes – BRT, express bus, streetcar, urban rail

0 Re-calibrate based on updated household and on-board survey

0 Move drive to Razorback Transit under auto nest (auto intercept) .

0 As part of University sub-model (see next slide)

Existing Model Components

0 University sub-model 0 All U of A university student trips modeled 0 Include NWACC students 0 Incorporation of the University Transportation Study results

0 Special Events 0 Razorback football 0 Bikes, Blues and BBQ

0 Visitor Model 0 Possibly using AirSage data 0 External, Internal model

0 Mid-day Circulator model 0 Streetcar ridership

New Model Components

Other Types of Models

0 Truck and/or Freight

0 Visitor model

0 Bike

0 Land-use

0 Economic

0 Integrated land-use/transportation models

0 Regional

0 Statewide

0 National

Questions?

Cristina Scarlat – cscarlat@nwarpc.org or 479 751-7125