Baltimore Red Line: Challenges of a Large Model Area Presented by: Mahmood Shehata, P.E. McCormick Taylor, Inc. Philadelphia, PA Presented to:PTV Users Group Meeting May 16, 2008 Philadelphia, PA
Presentation Topics Introduction to Baltimore Red Line Work Sharing and Modeling Standards Downtown Base Model Development Model Calibration Techniques and Obstacles Coding of Alternatives – Including TFlow Fuzzy Lessons Learned
Introduction to Baltimore Red Line
Introduction to Red Line 12-mile East-West Corridor Western Suburbs through Downtown Baltimore to Eastern End of Baltimore City Potential BRT or LRT Corridor Alternatives Analysis for DEIS and New Starts
Red Line Corridor
Existing Transit Services Local, Express, and Commuter Bus Metro Subway – NW Suburbs to Downtown Baltimore Central Light Rail Line – Northern Suburbs through Downtown to Southern Suburbs and Airport MARC Commuter Rail – From NE Suburbs to SW Suburbs and Washington, DC Existing E-W service limited, including only one high-speed bus line
Comprehensive System Red Line Part of Regional Plan Expand Existing System
Three Distinct Areas Proposed Line Serves 3 Distinct Areas: West Baltimore and Western Suburbs Downtown Baltimore East End (Fells Point / Canton) 22 Proposed Stations
West Baltimore and Western Suburbs Security Boulevard – MD 122 Eastern Terminus of I-70 – Proposed Station Location US 40 in West Baltimore
The “Trench” US 40 Between West Baltimore Commuter Rail and Downtown
Downtown / Inner Harbor Baltimore St - Location of Most Alignments Pratt St – Source of Congestion in VISSIM Models
Fells Point / Canton Narrow Street Grid in Fells Point Wider Boston Street to south of City Grid in Canton Area
Work Sharing and Modeling Standards
Synchro initially utilized to evaluate corridor MTA and project team agreed upon VISSIM to analyze entire corridor, including preemption and TSP Five Separate Consultants to complete VISSIM models Single consultant chosen for oversight
Work Sharing and Modeling Standards Each consultant assigned a portion of study area to model Model Areas chosen using logical break points: 1-2: Park and Ride (Baltimore County and West Baltimore) 2-3: W.Baltimore MARC Station 3-4: US 40 / MLK Blvd. 4-5: President St / Central Avenue
Model Areas 1-2 Modeling Team 1 Area Modeling Team 2 Area
Model Areas 2-3 Modeling Team 2 Area Modeling Team 3 Area
Model Areas 3-4 Modeling Team 3 Area Modeling Team 4 Area
Model Areas 4-5 Modeling Team 4 Area Modeling Team 5 Area
Work Sharing and Modeling Standards Standards Developed for Modeling Consistency Speed profiles, turning speeds, links and connectors, etc. Vehicle profiles uniform – including articulated buses and LRT vehicles CD Distributed with base.inp file Provided identical vehicle profiles for all models. Aerials with.bgr - georeferenced models
Work Sharing and Modeling Standards Spreadsheet Developed and Distributed to Ensure Model Consistency
Work Sharing and Modeling Standards Standards were developed for most components of VISSIM models
Downtown Model Development
Approximately 95 signalized intersections N-S Arterials on east and west end Alternating one-way E-W Streets
Downtown Model Development Synchro base model previously developed Small blocks, Unique Lane and Turn Restrictions VISSIM model developed from scratch Divided into 3 sections to setup model: MLK to Howard ( ) Howard to Calvert ( ) South to Central ( ) Read Additionally used
Unique Characteristics of Downtown Model On-Street Parking / Loading Zones in some locations Off-Street Parking as source/sink Initial Model did not include Conway Street At times, I-95 and I-395 backs into Conway St
Unique Characteristics of Downtown Model Initial Model Area Conway St. Intersection of Howard and Conway Constricting Point
Unique Characteristics of Downtown Model Routing decisions through 2,3, even 4 intersections (in existing conditions model)
Unique Characteristics of Downtown Model Model accounts for high pedestrians, including Leading Pedestrian Intervals
Public Transportation System Bus routing and headways obtained with established schedules Bus stops field verified Central Light Rail Line included Dwell Times: sec. per bus sec. for Central Light Rail
Central Light Rail Line
Result – Comprehensive Downtown Baltimore Model
Model Calibration Techniques
Calibration Standards: Within 10% of counted link volumes Within 20% of Travel Times
Model Calibration Techniques Travel Times calculated in field to mimic bus movements Travel Times in model extracted to reflect field collection For all vehicles, VISSIM expected to be higher Buses comparable, less dwell time
Model Parameters Adjusted Driver Behavior Parameters Safety Distance Adjustment Lane Changing Behavior “Saturation Flow Rate” – Additive and Multiplicative Distances Some Links altered more than others Creation of more than one parameter set per link type (Urban1, Urban2) Account for more friction (e.g. Pratt St) Minimum Lane Changing Distance (Connectors)
Results All 5 modeling teams met all calibration parameters set! Higher confidence in model essential for alternatives analysis
Alternatives Analysis
Alternative Model Coding Design Year of 2030 All initial volume growth based on regional MPO travel demand model Western Area models (Groups 1-3) utilized growth rate from MPO model Downtown and East End account for parallel links and alternate routing by using TFlow Fuzzy Logic
Use of TFlow Fuzzy Existing VISSIM network routing and MPO growth used to develop base VISUM network TFlow Fuzzy accounted for diversion – alternate one-way streets Aided in redistribution of traffic in both Downtown and Fells Point
Alternatives Considered Shared Use BRT Exclusive BRT Exclusive LRT Exclusive BRT with Downtown Bus Tunnel Exclusive LRT with Downtown Tunnel
Exclusive BRT – “Trench” Area
Exclusive BRT – Baltimore / Lombard Transit Couplet
Modeling Approach and Consistency BRT/LRT Vehicle Characteristics consistent Headways Based on Operating Plan for EIS Dwell Times: Sec. for BRT; sec. for LRT Vehicle Change and Clearance Intervals based on operating speeds and vehicle characteristics
Modeling Approach and Consistency Removal of existing travel lanes for exclusive transit lanes is anticipated to cause trip diversion CBD, Fells Point – both are based on city grid Use of T-Flow Fuzzy Logic in VISUM to estimate diversions
Lessons Learned
Establish a consistent approach at start of model process Project controls / standards allow for easier and more accurate QA/QC review Field verification a must for all elements Understand how calibration data was collected Regular communication between model teams
Lessons Learned VISUM / VISSIM integration utilizing TFlow Fuzzy ideally should be included early in model development Take care in optimizing signal timings to minimize transit delay, vs. roadway corridor delay Traffic signal timing plans should reflect how surface transit travels through the intersection Communicate level of modeling effort early in the project
Lessons Learned Expect the unexpected!!!
Thank you! Mahmood Shehata, P.E. Project Engineer McCormick Taylor, Inc Market St, 10 th Floor Philadelphia, PA (215)