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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

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Baltimore red line challenges of a large model area

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
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 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

Existing transit services
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
Comprehensive System

  • Red Line Part of Regional Plan

  • Expand Existing System

Three distinct areas
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
West Baltimore and Western Suburbs

Security Boulevard – MD 122

Eastern Terminus of I-70 – Proposed Station Location

US 40 in West Baltimore

The trench
The “Trench”

US 40 Between West Baltimore Commuter Rail and Downtown

Downtown inner harbor
Downtown / Inner Harbor

Baltimore St - Location of Most Alignments

Pratt St – Source of Congestion in VISSIM Models

Fells point canton
Fells Point / Canton

Wider Boston Street to south of City Grid in Canton Area

Narrow Street Grid in Fells Point

Work sharing and modeling standards1
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 standards2
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
Model Areas 1-2

Modeling Team 1 Area

Modeling Team 2 Area

Model areas 2 3
Model Areas 2-3

Modeling Team 2 Area

Modeling Team 3 Area

Model areas 3 4
Model Areas 3-4

Modeling Team 3 Area

Modeling Team 4 Area

Model areas 4 5
Model Areas 4-5

Modeling Team 4 Area

Modeling Team 5 Area

Work sharing and modeling standards3
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 standards4
Work Sharing and Modeling Standards

  • Spreadsheet Developed and Distributed to Ensure Model Consistency

Work sharing and modeling standards5
Work Sharing and Modeling Standards

  • Standards were developed for most components of VISSIM models

Downtown model development1
Downtown Model Development

  • Approximately 95 signalized intersections

  • N-S Arterials on east and west end

  • Alternating one-way E-W Streets

Downtown model development2
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 (600-650)

    • Howard to Calvert (650-700)

    • South to Central (700-750)

  • Read Additionally used

Unique characteristics of downtown model
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 model1
Unique Characteristics of Downtown Model

Initial Model Area

Conway St.

Intersection of Howard and Conway Constricting Point

Unique characteristics of downtown model2
Unique Characteristics of Downtown Model

  • Routing decisions through 2,3, even 4 intersections (in existing conditions model)

Unique characteristics of downtown model3
Unique Characteristics of Downtown Model

  • Model accounts for high pedestrians, including Leading Pedestrian Intervals

Public transportation system
Public Transportation System

  • Bus routing and headways obtained with established schedules

  • Bus stops field verified

  • Central Light Rail Line included

  • Dwell Times:

    • 15-25 sec. per bus

    • 30-50 sec. for Central Light Rail

Model calibration techniques1
Model Calibration Techniques

  • Calibration Standards:

    • Within 10% of counted link volumes

    • Within 20% of Travel Times

Model calibration techniques2
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
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)


  • All 5 modeling teams met all calibration parameters set!

  • Higher confidence in model essential for alternatives analysis

Alternative model coding
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
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
Alternatives Considered

  • Shared Use BRT

  • Exclusive BRT

  • Exclusive LRT

  • Exclusive BRT with Downtown Bus Tunnel

  • Exclusive LRT with Downtown Tunnel

Modeling approach and consistency
Modeling Approach and Consistency

  • BRT/LRT Vehicle Characteristics consistent

  • Headways Based on Operating Plan for EIS

  • Dwell Times: 15-30 Sec. for BRT; 30-50 sec. for LRT

  • Vehicle Change and Clearance Intervals based on operating speeds and vehicle characteristics

Modeling approach and consistency1
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 learned1
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 learned2
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 learned3
Lessons Learned

Expect the unexpected!!!

Baltimore red line challenges of a large model area

Thank you!

Mahmood Shehata, P.E.

Project Engineer

McCormick Taylor, Inc.

2001 Market St, 10th Floor

Philadelphia, PA 19103

(215) 592-4200