Next Generation Simulation Core
Algorithms and Data Sets
presented by
Vassili Alexiadis
Cambridge Systematics, Inc.
Identify and
Prioritize Core
Prioritized Core Algorithms
Project Approach
High-Level Plan and
Assessment for
Core Algorithms
Validation, and
Data Collection
High-Level Plan
for Validation
Data Requirements
High-Level Plan
for Data Sets
Data Formats
Establish NGSIM
Data Formats
• Algorithms, Software
for Testing, and
• Validation Databases
and Procedures
• Validation Data
Establish and Maintain Web Site and Repository
Interaction with the Stakeholder Group and User Community
Project Management and Program Support
Project Organization
Federal Highway
John Halkias
Gene McHale
Quality Assurance/
Quality Control
Lance Neumann (CS)
Cambridge Systematics, Inc.
Senior Advisors
Vassili Alexiadis (CS)
Moshe Ben-Akiva (MIT)
Alexander Skabardonis (UCB)
Hani Mahmassani (UMD)
Pitu Mirchandani (UAZ)
Panos Michalopoulos (UMN)
Principal Investigator
Project Management
Web Site
Data Formats
Vassili Alexiadis (CS)
Vassili Alexiadis (CS)
Nathan Clark (CS)
Richard Margiotta (CS)
Data Sets
Core Algorithms
Richard Margiotta (CS)
Larry Head (SGTS)
Richard Dowling (DA)
Website -
 Objectives
Provide a user-friendly environment for NGSIM information
Provide a community workplace
Provide software, data, and documentation repository
Allow for algorithm/data project management
 Functionality
NGSIM program information
News and event items
User registration capabilities
Document downloads
Manage program documents
Links to other relevant efforts
NGSIM team, stakeholder and public discussions
Website -
Using the site:
• Register, via the front page
• View the ‘documents’ section, for relevant downloads
• Check the site weekly, for news and events updates
• Participate in discussion lists
Previous Requirements Work
 FHWA-led workshops
• Identified basic requirements
• Ranked requirements, based on need
 Overlap with this workshop
• Focused on micro-simulation models
 Differences: this workshop is:
• Not focused on developing a full NGSIM model
• Focused on core behavioral algorithms
Workshop Objectives
 Requirements elicitation
• Users: What needs to be advanced in the state of the
• Modelers: What needs to be advanced in the state of the art?
• Developers: How should NGSIM be formulated to be useful to
software developers?
 Requirements prioritization
• Users: based on need
• Modelers: based on development risk
• Developers: based on development cost
 Identify available data sets and algorithms
Workshop Agenda
 Monday
• 8:30 - noon: Plenary session
• Noon - 1:00: Lunch (group)
• 1:00 - 5:00: Breakout sessions (Users, Modelers, Developers)
• 5:00 - 7:00: Social (Hors d'oeuvre and cash bar)
 Tuesday
• 8:00 - 10:00: Plenary session
• 10:00 - 1:00: Breakout sessions
• 2:00 - 5:00: Individual meetings with developers, as needed
Workshop Format
 Users and Modelers
• Identify and rank requirements
- In reference to specific modeling scenarios/situations
- As combinations of influencing factors that affect travel
behavior (list is provided in breakout material)
• Describe a few scenarios that you want to model adequately,
but feel you cannot; May include scenarios you have or
have not attempted to model
 Developers
• Input on format and documentation of NGSIM algorithms
and data sets
• Identify potential sources of algorithms and data sets
• Input on validation procedures
Workshop Rationale
 Workshop purpose
• Identify those factors that are most important to users and
use this information to shape focus efforts on behavioral
• Practical focus - Not theoretical focus
• Supplemental - Not a wholesale rethinking of ongoing FHWA
needs assessment
 Example
• Users: Current models do not do a good job in modeling
ramp metered freeways under bad weather conditions
• NGSIM focus on car following and lane changing under these
conditions. Gather data sets, and develop/test algorithms to
model lane changing or car following under these conditions.
Desired Outcomes
• Simulation model requirements
- Through identification and ranking of scenarios/situations
• Structural critique
- Discuss NGSIM framework
• Process critique
- Issues with process
• Input on format and documentation of NGSIM algorithms and
data sets
• Potential sources of algorithms and data sets
• Input on validation procedures