Atlanta Chattanooga High Speed Ground Transportation Modeling Techniques

Transcription

1 Atlanta Chattanooga High Speed Ground Transportation Modeling Techniques Atlanta Model Users Group Meeting December 4, 2009 Steer Davies Gleave 883 Boylston Street, 3rd Floor Boston, MA

2 Agenda Presentation of Steer Davies Gleave Atlanta-Chattanooga HSGT study background Intercity auto diversions Intra ARC travel HJAIA access Lovell Field air route choice 1

3 Presentation of Steer Davies Gleave A UK-based transport consultancy, approx. 400 employees worldwide Offices in UK, Italy, Spain, Abu Dhabi, Chile, Columbia, Brazil, Mexico, Canada and US: San Juan and Boston SDG Boston office created by transfer of the Charles River Associates transportation planning group in January 2009 Our group has worked in the Atlanta area since early 2001: NWCS, SRAS CTPs for Cherokee, Cobb, Fayette, Spalding Counties, City of Atlanta Most of our work has been demand modeling and related activities We have also worked on HSR ridership studies around the country: Texas Triangle, DC-Baltimore maglev, early versions of California HSR Extensive work for USDOT on the Acela in the Northeast Corridor We have either worked on or reviewed for USDOT the forecasts for all officially designated HSR corridors 2

4 Atlanta-Chattanooga HSGT Study Background Can t say much because the work is still in process Tier I EIS of high-speed ground transportation options in the Atlanta- Chattanooga corridor Led from GDOT s Division of Intermodal with TDOT partnership Work carried out by a relatively large team primed by Earthtech (now AECOM) Work begun about two years ago (pre recent Federal HSR program) An initial forecasting model was developed and used to provide inputs to a screening process, the results of which are under review Meanwhile we are proceeding to enhance and update the initial model by Conducting a household travel survey in the corridor, with results used to re-estimate some relationships in the initial model Referring to most recent versions of other model systems developed in the corridor 3

5 Overview of the Presentation We will concentrate on presenting the architecture of the model, but will not discuss model specifications or coefficient estimates We will highlight some of the interesting technical issues addressed in developing the model We won t talk about alternatives or analysis results The model consists of four main components: Intercity automobile diversions Intra ARC travel HJAIA access Lovell Field air route choice 4

6 Intercity Auto Diversion Model: Overview Objective: to calculate the number of trips that will divert from auto Model Structure: Uses Business and Nonbusiness trip purposes Subject Year O/D Travel En Route Captive Noncaptive Destination Captive Auto Diversion Model HSGT Auto 5

7 Intercity Auto Diversion Model: the Model Functions Auto: U auto = 1 Cost auto + 2 Travel Time auto Noncaptive HSGT: U HSGT = + 1 Cost HSGT + 2 Travel Time HSGT + 3 Access/Egress Time HSGT + 4 Waiting Time HSGT + 5 Access/Egress/Wait Time Fraction HSGT Destination Captive HSGT: U HSGT = + 1 Cost HSGT + 2 Travel Time HSGT + 3 Access/Egress Time HSGT + 4 Waiting Time HSGT + 5 Access/Egress/Wait Time Fraction HSGT + Transfer Penalty where: = mode specific constant Cost = total modal cost Travel Time = line haul portion of trip travel time Access/Egress Time = total access and egress travel time Waiting Time = waiting time for HSGT Access/Egress/Wait Time Fraction = access + egress + wait time portion of total travel time Transfer Penalty = dummy variable indicating if transfer (e.g. rental car, taxi) is required Household travel survey recently conducted to refine coefficients 6

8 Intercity Auto Diversion Model: Highway Network Prepared by combining highway networks of 4 model systems 7

9 Intercity Auto Diversion Model: Highway Travel Times The highway network provides inputs into the model Auto: travel time and distance HSGT: access time and distance The link travel times were taken from the loaded network travel times of the 4 source model systems Travel times for the gap areas were determined using the following speeds: Limited access freeways: mph Arterial highways: mph We made an adjustment to the ARC s limited access freeway travel times Established relationship between actual travel speeds collected by GDOT and base year ARC s forecasted speeds Adjusted future year travel speeds using this relationship 8

10 Intercity Auto Diversion Model: HSGT Inputs Line haul travel times developed from simplified train simulation Wait time set as transformation of frequency Access/egress time and distance from the highway network Distances were converted into costs Fares were set with combination of boarding and distance-based components Relative magnitude of fares referenced against corridor airfare and Northeast Corridor Acela 9

11 Intercity Auto Diversion Model: Auto Trip Table The auto trip table represents the intercity demand We used a weaving process to combine the external trip tables from the 4 source model systems Only trips with external for at least one trip end For matching external stations, average flow and proportion We massaged the county-county trip flows to develop more reasonable control totals Referred to the county-county work trip flows in the Census Journey to Work survey Used gravity model-type logic Within county, trips proportioned to TAZ using relationship from weaving process 10

12 Origins - Network 2 Origins - Network 1 Origins - Network 1 Intercity Auto Diversion Model: Auto Trip Table Weaving Process Network 1 Network Destinations - Network Total Total 90 Destinations - Network Total => Destinations - Network Total Total Total 11

13 IntraARC Travel Model: Overview Objective: to calculate the number of trips with both ends in the ARC model region that will use the HSGT Model Structure: adaptation and extension of the ARC model system s mode choice model We aimed to preserve logic and functionality of the ARC model while incorporating this new mode Treated HSGT with Commuter Rail coefficients Added a premium transit mode choice model with logic of ARC mode choice model 12

14 IntraARC Model: Model Flow Model Run With Full Feadback Loop Skimming with HSGT Like Commuter Rail Skims with HSGT as Own Mode Skims Needed For Mode Choice Model ARC Mode Choice Model Auto Trips Premium Transit Trips Local Transit Trips Premium Transit Mode Choice Model HSGT Trips Other Premium Transit Trips Transit Assignment 13

15 HJAIA Access Model A departing passenger survey at HJAIA in 2001 showed that 86% of air passengers who arrive at HJAIA by a surface mode come from the HSGT corridor Of those corridor trips, 98% come from the ARC 20-county region We focused on the ARC region to model impacts of HSGT on current surface access to HJAIA The ARC model treats HJAIA as a special generator Trips to/from HJAIA are forecast using logic that is somewhat different from that for other intra-arc region trips Travelers are segmented into residents and non-residents Trip purposes are business and non-business Separate generation, distribution and mode choice models apply The mode choice model has a nested logit form, different for residents and non-residents It has a public transport nest containing taxi and transit options 14

16 HJAIA Access Model We added a HSGT option to the public transport nest Resident Private Car Public Transport Dropped-Off Drive Self HSR Taxi Transit Non-Resident Dropped-Off Rental Car Public Transport HSR Taxi Transit 15

17 HJAIA Access Model We retained the ARC airport access model s transit utility function coefficients for HSGT Of course HSGT impedances (walk time, wait time, run time and fare) were skimmed separately based on HSGT characteristics We manually adjusted the alternative specific constant used in the HSGT utility function It was specified as a fraction of the transit utility s ASC We iteratively adjusted the fraction, did a model run, and examined the predicted HSGT HJAIA access ridership for reasonableness This was integrated into the modified ARC model that we used for the HSGT study Executed as part of normal run stream 16

18 Lovell Field Air Route Choice Model Forecast how many air passengers currently traveling to/from Chattanooga would divert to the HSGT to access HJAIA Majority of air travelers to/from CHA connect through one of six hubs: Atlanta, Charlotte, Chicago, Houston, Dallas and Memphis Introduction of HSGT may cause more air travelers to connect through ATL using the HSGT connection between Chattanooga and Atlanta First estimate a model that relates market shares of O-D air routes to/from CHA to each alternative route s level of service The model was estimated using actual route shares and attributes, representing essentially all air trips in/out of CHA Then forecast the diversion of intercity air travel to HSGT, given the anticipated HSGT service levels between Lovell Field and HJAIA Possible new air travel induced by HSGT connection between CHA and ATL was not considered Possible re-routing of current HJAIA traffic to CHA not considered 17

19 Lovell Field Air Route Choice Model O/D Chattanooga-Tampa Step 1 Step 2 Route 1 Route 2 New HSR Alternative CHA-ATL-TPA CHA-CLT-TPA CHA-ATL*-TPA 92% 8% ATL*: New HSR connection between Atlanta and Chattanooga Step1: Calibration of the model, to reproduce the observed market shares in the absence of the HSR alternative Step2: Application of the model to the introduction of the new HSR alternative 18

20 Lovell Field Air Route Choice Model Development of the Air Route Choice Model Using 2008 data, we identified 172 O-D city pairs served from CHA by routes with up to 2 legs Most O-D routes involve connections at Atlanta, Charlotte, Chicago, Dallas, Houston or Memphis We characterized each O-D route by a variety of service attributes Data sources included 10% airline ticket sample (DB1B), on-time performance data, and data directly provided by smaller carriers We estimated a logit-form model using route share data Significant route attribute variables included: Elapsed time (from departure to arrival including connections) Schedule frequency Connection time Late night arrivals (dummy) Others Fare not significant 19

21 Lovell Field Air Route Choice Model Application of the Air Route Choice Model Two scenarios may be considered Air/HSGT code-sharing between CHA and ATL: reduced air service Continued CHA-ATL air service with competitive response of carriers Application of the model requires some assumptions Because air fare was not significant in the route choice model, assume that HSGT fare is comparable to air Detailed scheduling not considered in the models, assume that HSGT schedule is comparable to air (for connections) HSGT connect penalty imposed to reflect transfer time from HSGT station to terminal, and additional security clearance time at HJAIA 20