Traffic Analysis Toolbox Volume XIV: Guidebook on the Utilization of Dynamic Traffic Assignment in Modeling
B. Foundations of Dynamic Traffic Assignment (DTA) Workshop: Selected Recent DTA Analyses
The Federal Highway Administration assembled this list of recent examples (2009 and later) of DTA analyses as a supplement to its Foundations of Dynamic Traffic Assignment Workshop. The list of examples was collected from public sector agencies, academia, and consultants to provide examples from a broad cross-section of application areas that will assist students in applying DTA techniques to conduct traffic analyses in their regions.
Work Zone/Construction
1. Project Title: Atlanta’s Memorial Drive DTA Case Study, part of ARC’s Strategic Regional Thoroughfare Plan/Regional Thoroughfare Network
Location Modeled: Atlanta, Georgia, area bounded on the north by Ponce de Leon Avenue, on the south by Glenwood Avenue, on the east by Moreland Avenue and on the west by I-75/85 Downtown Atlanta CBD
Project Dates: 2010-2011
Sponsor: Atlanta Regional Commission (ARC)
Contact: Guy Rousseau
Application Used: Cube Voyager/TP+, Cube Avenue DTA, VISSIM microsimulation
Project Description: This mesoscopic analysis was carried out by using dynamic traffic assignment (DTA) to address the issue of motorist selection of differing routes during periods of congestion along with the changing of these routes within the congested time period itself. This DTA process allowed for an examination of queues and delays associated with congestion. DTA procedures have recently been tested successfully in the Atlanta metropolitan 20-county region to determine its viability in large scale applications. This step down process provides the necessary integration of macroscopic and mesoscopic analysis procedures to ensure analysis consistency and compatibility. This level of analysis allowed for an examination of travel and transportation network characteristics during peak periods. The trips for each of the AM and PM peak periods within the study area are developed by extracting the trips from the regional travel demand model using hourly assignments. The third level of analysis is microscopic analysis which dealt with the detailed operational characteristics of the transportation network at specific locations, along the corridor, or within isolated areas of the overall corridor. This microscopic analysis was carried out by extracting the area to be studied in detail from the mesoscopic model and using more rigorous analysis procedures of a micro traffic simulation model. The traffic volumes and travel patterns established in the mesoscopic analysis are incorporated into the microscopic analysis, thus maintaining the integration with the macroscopic and mesoscopic levels of analysis. The end result of the DTA analysis is a recommended design concept developed through a cooperative process that, in turn, mitigates potential conflicts during the environmental assessment (as prescribed by the National Environmental Protection Act (NEPA)), final design and construction phases of the project. As such, the ARC will be developing corridor plans that lead to a project further along in the implementation stages. In addition, regional travel trends will be considered in developing the concept by carrying through the travel analysis methodology tested in the case study process. Another potential result of the DTA analysis is the identification of short-term safety and/or operational improvements for the corridor.
Related Links: Atlanta Regional Commission: Strategic Regional Thoroughfare Plan
2. Project Title: Presidio Parkway Construction Traffic Management Plan
Location Modeled: Northwest quadrant of the City of San Francisco, California
Project Dates: August – December 2009
Sponsor: San Francisco County Transportation Authority
Contact: Elizabeth Sall
Application Used: Dynameq
Project Description: Doyle Drive is the 2-mile long southern approach to the Golden Gate Bridge. Carrying roughly 17,000 weekday transit riders and 127,000 weekday persons in cars, it is both the primary highway and transit link from San Francisco and the South Bay, to the North Bay Counties as well as an essential east-west connection for trips within San Francisco. Built over 60 years ago, Doyle Drive is also one of the most seismically unfit facilities in California and plans for its replacement facility, the Presidio Parkway, have been underway since the 1970s. The final funding gap was closed by the American Recovery and Reinvestment Act of 2009 (ARRA) to facilitate the signing and certification of the final joint EIS/EIR. Accordingly, the construction time line has been significantly accelerated in order to meet ARRA requirements. This left the San Francisco County Transportation Authority (SFCTA), Caltrans and other local agency partners with little time to evaluate the traffic impacts from the construction of the Presidio Parkway. Recognizing the need to identify potential bottlenecks and queues as a result of the construction (and test possible solutions to these issues), SFCTA decided to implement Dynamic Traffic Assignment (DTA) for this quadrant of the city.
Related Links: Presidio Parkway – San Francisco’s Gateway
3. Project Title: Interstate 10 Corridor Improvement Analysis
Location Modeled: Interstate 10, El Paso, Texas
Project Dates: 9/2010 – 8/2011
Sponsor: Texas Department of Transportation
Contact: Jesus Heredia, P.E.
Application Used: DynusT-VISSIM, Synchro (Multi-resolution)
Project Description: The Texas Transportation Institute conducted a corridor analysis on Interstate 10 in El Paso to determine the impact of direct connectors at the Loop 375 interchange. The goal was to determine if the proposed connectors would alleviate severe congestion at an adjacent diamond interchange or if additional roadway construction (e.g., additional diamond interchanges, ramp reversals,) would be needed. A DTA simulation-based modeling approach utilizing DynusT was used in the analysis. DynusT networks were coded for future conditions to analyze traffic patterns and rerouting based upon proposed diamond interchange construction and ramp reconfigurations. Future network conditions included a proposed tolling scenario on Border Highway.
Related Links: PowerPoint slides available by request.
Transit Operations
4. Project Title: Geary Boulevard Bus Rapid Transit Environmental Impact Report
Location Modeled: Northwest quadrant of the City of San Francisco, California
Project Dates: Spring 2010 – ongoing
Sponsor: San Francisco County Transportation Authority
Contact: Elizabeth Sall
Application Used: Dynameq
Project Description: In order to model the impacts and benefits of a potential Geary Boulevard Bus Rapid Transit, the Authority was able to successfully link the SF-CHAMP regional activity-based travel demand model with the subarea DTA model by directly using raw SF-CHAMP trip tables for the base and future years. The DTA model in turn provided reasonable intersection-level data for use in a traffic microsimulation model. The DTA model was validated to several hundred mainline and intersection counts as well as travel speeds. The project team developed open-source python-based tools to make quick work of most calibration, validation, and model input, output, and summary tasks. The DTA model provided two main benefits: (1) a needed link between a regional travel demand model and a traffic microsimulation model able to more reliable way to model traffic diversions in the corridor; (2) more reliable travel time and Level of Service (LOS) outputs of different scenarios for areas that were not scoped to be modeled by traffic microsimulation.
Related Links: Easy Breezy Beautiful DTA Modeling of the Geary Boulevard Bus Rapid Transit Project – Was it Really That Simple?
San Francisco County Transportation Authority – Geary Corridor Bus Rapid Transit
5. Project Title: West Palm Beach Transit Oriented Development Traffic Impact Analysis
Location Modeled: Southeast Florida (regional model), West Palm Beach (detailed subarea)
Project Dates: 2009 – ongoing
Sponsor: Florida Department of Transportation, District 6
Contact: Ana Elias
Application Used: Cube Base, Cube Voyager, Cube Analyst (ME), Cube Avenue
Project Description: District 4 of the Florida Department of Transportation developed a traffic impact analysis toolkit initially used to study a transit- oriented development in West Palm Beach. Dynamic traffic analysis was included in this toolkit to improve temporal specificity. The resulting analysis toolkit is capable of extracting time-varying trip tables from the Southeast Regional Planning Model (SERPM), calibrating these to observed traffic counts by time of day (using dynamic origin-destination matrix estimation techniques), and performing a hybrid static/dynamic traffic assignment on the full regional network in order to extract a fully dynamic traffic simulation model for any arbitrary user-defined subarea of this region.
Related Links: FDOT D4 DTA/TIA Toolkit
Truck Operations/Border Crossings
6. Project Title: Dynamic Modeling Methods for Analyzing New Truck Routes for the BOTA Port-of-Entry
Location Modeled: Bridge of Americas – El Paso/Cuidad Juarez, Mexico
Project Dates: 10/2010 – 1/2011
Sponsor: Texas Department of Transportation
Contact: Omar Madrid, P.E.
Application Used: DynusT-VISSIM, (Multi-resolution)
Project Description: The Texas Transportation Institute examined the effects of new truck routes destined for the Bridge of the Americas (BOTA) Port-of-Entry in El Paso, Texas. The analysis determined how the proposed truck rerouting would influence the surrounding transportation system and whether the changes would improve southbound traffic flow into Mexico or have an adverse effect. The analysis used a regional dynamic traffic assignment model (DynusT) to simulate present day network conditions at the system-wide level. This is necessary to determine both car and truck paths in and around the study area. Once the network model was simulated to equilibrium conditions, a sub-area cut will be extracted and converted to a microscopic model (VISSIM) which was capable of analyzing various vehicle classes at a high level of detail.
Related Links: PowerPoint slides available by request.
7. Project Title: Integrated Dynamic Bi-National Travel Demand Model
Location Modeled: El Paso/Cuidad Juarez, Mexico border region
Project Dates: 9/2010 – 8/2011
Sponsor: Texas Transportation Institute – Center for International Intelligent Transportation Research
Contact: Rafael Aldrete, Ph.D.
Application Used: TRANUS – VISUM – DynusT- (Multi-resolution)
Project Description: The objective of this project was to develop a mesoscopic bi-national (i.e. El Paso – Juarez) simulation model capable of running DTA to conduct transportation studies in the border region. In order to develop the DTA model, a combination of macroscopic and mesoscopic transportation planning software (e.g. VISUM, TRANUS, and DynusT) was required. In addition, researchers used a VISUM-VISUM-DynusT Converter (VDC) tool previously developed by the Texas Transportation Institute and PTV America to integrate the transportation network between the macroscopic and mesoscopic level. The dynamic bi-national travel demand model allowed researchers to analyze the impact of proposed new port-of-entry infrastructure and the impacts of existing border crossing during recurring and non-recurring events (e.g., bridge closure due to bomb threat, protesters, etc.). In addition, variable tolling options allowed for a more robust approach to analyzing proposed managed lanes in the region.
Integrated Corridor/Systems Management
8. Project Title: A DTA model platform and analysis approach for the City of Bellevue
Location Modeled: Cities of Bellevue, Kirkland and Redmond and their fringe area, with detailed network and traffic controls in the City of Bellevue limits and its vicinity.
Project Dates: Ongoing
Sponsor: City of Bellevue
Contact: Hu Dong or Judy Clark
Application Used: Dynameq and EMME
Project Description: Unlike other DTA models nationwide developed specifically for a transportation project, The City of Bellevue is trying to build a generic DTA platform for the whole city area and develop a streamlined procedure for fast and efficient application for the City’s transportation projects. This platform includes a base year DTA model and a future year (2030 at this time) baseline. The City is developing a procedure that starts from its BKR travel demand model which covers a much larger area than the DTA model, and includes how to test a transportation project under the new platform, how to report the DTA outputs, and how to disseminate the output information to the transportation professional and public. The base year DTA model has been calibrated and the future baseline is under fine-tuning when this project information is provided.
Related Links: “Sensitivity Test on Dynameq, View from Practice,” TRB Annual Conference, January 2011.
9. Project Title: Thurston Regional Planning Council (TRPC) Smart Corridors Project
Location Modeled: Thurston County, Washington
Project Dates: 2009 – ongoing
Sponsor: Thurston Regional Planning Council
Contact: Natarajan Janarthanan or Ming-Bang Shyu
Application Used: DYNAMEQ
Project Description: TRPC is an intergovernmental board made up of local government jurisdictions within Thurston County in Washington State. The county has an area of 727 square miles and a population of little less than 250,000. The county is the home of the State’s capitol, city of Olympia. TRPC received Congestion Mitigation and Air Quality (CMAQ) grant to reduce PM10 emissions in the County. TRPC decided to focus their efforts on two key corridors in the county and focused on smart corridor techniques. TRPC had an EMME model for the base and future year. But they wanted to build a mesoscopic model to evaluate signal coordination and transit signal priority, to integrate arterial/freeway management and to measure PM10 emissions. INRO’s software product DYNAMEQ was chosen by the TRPC. The efforts to build a mesoscopic model for the whole county but focusing on two main corridors and areas surrounding them were undertaken in 2009. The existing year model was completed before the end of the year 2009. This project is on-going and managed by Jailyn Brown of Thurston Regional Planning Council.
Related Links: PowerPoint Slides available by request.
10. Project Title: Manhattan Traffic Model
Location Modeled: The whole of the island of Manhattan in addition to parts of New Jersey, the Bronx and Brooklyn
Project Dates: 9/2009 – 9/2011
Sponsor: New York City DOT
Contact: Mike Marsico
Application Used: Aimsun
Project Description: The Manhattan Traffic Model (MTM) is a multi-tier model developed for NYCDOT by Cambridge Systematics, STV, and TSS- Transport Simulation Systems in order to assess traffic operations for Manhattan, New York. NYCDOT is working with other regional agencies to coordinate modeling activities where the MTM network will be made available to address cumulative network impacts of construction projects, roadway closures and traffic operations plans, as well as to provide a point of departure for future work and the creation of a sustainable regional model.
Related Links: New York Department of Transportation: 34th Street Transitway – Traffic Analysis Summary
11. Project Title: Maricopa Association of Governments Inner Loop Traffic Operations Model Development
Location Modeled: Greater Phoenix, Arizona
Project Dates: ongoing
Sponsor: Maricopa Association of Governments (MAG)
Contact: Bob Hazlett, P.E.
Application Used: TransModeler (DTA based on microscopic traffic simulation)
Project Description: Maricopa Association of Governments (MAG) sponsored a project to develop a 500 square-mile simulation model for the inner loop region of the Phoenix metropolitan area. This project includes the development of the simulation network, input of the traffic control, and demand estimation (including congested travel time estimation via dynamic traffic assignment (DTA). The geographic area comprises a high-capacity network of arterials and major freeways in the most populous region of the metropolitan area.
Related Links: PowerPoint slides available by request.
12. Project Title: Toronto 400 Series
Location Modeled: Area between (and including) Highway 400, 401, 404 and 407 in the Greater Toronto Area
Project Dates: 08/2008 – ongoing
Sponsor: Ministry of Transportation of Ontario (MTO)
Contact: Goran Nikolic
Application Used: Aimsun
Project Description: The proof-of-concept is for the simulation framework covering the 400-series highway network and major arterial roads in the Greater Toronto Area.
Related Links: Aimsun: A Model Approach
Traffic Technology Today: A Virtual Solution for Real-World Analysis
13. Project Title: Modym (Montreal, Canada)
Location Modeled: The island of Montreal
Project Dates: 5/2011 – ongoing
Sponsor: Ville de Montréal
Contact: Francine Leduc
Application Used: Aimsun
Project Description: The City of Montreal wishes to build a reusable, super large-scale simulation base model of Montreal. EMViM modeling group is using Aimsun to provide an extensible modeling environment that can cover the entire island of Montreal and allow it to vastly expand the Montreal model. EMViM is using Aimsun’s micro-meso hybrid capability to overcome mesoscopic restraints, particularly on freeway merge and diverge sections and connections to arterial networks, where modelers can now zoom in for greater granularity.
Related Links: Aimsun: Supersize Me
14. Project Title: Integrated Corridor Management
Location Modeled: Minneapolis, Minnesota
Project Dates: 9/2006 – 8/2009
Sponsor: FHWA
Contact: Yi-Chang Chiu
Application Used: DynusT
Project Description: This project is aimed at establishing the ICM modeling methodologies and applying that to the Minneapolis Pioneer Site. In this project the UA team applied DynusT as the primary modeling tool. The DynusT modeling capabilities utilized in this project include the simulation-based DTA analysis encompassing information strategies, ramp metering, congestion pricing, and transit simulation and assignment, for various incident scenarios. The origin-destination (O-D) table and speed profile calibration procedure appeared to be effective and efficient in establishing a satisfactory baseline case.
Related Links: PowerPoint slides available by request.
Safety Analysis
15. Project Title: Loop 375/SH20 Alameda Interchange Safety Analysis
Location Modeled: Loop 375/SH 20 Alameda Diamond Interchange – El Paso, Texas
Project Dates: 4/2010 – 8/2010
Sponsor: Texas Department of Transportation
Contact: Gus Sanchez
Application Used: DynusT-VISSIM Synchro (Multi-resolution)
Project Description: The Texas Transportation Institute conducted a safety review of a diamond interchange and surrounding areas to determine long-term mitigation strategies aimed at reducing traffic accidents in the study area. DynusT was used to analyze long-term strategies that consisted of future network improvements. Long-term strategies included additional on and off ramps on Loop 375 up and downstream of the diamond interchange, additional roadway capacity, and proposed direct connectors to Cesar Chavez Border Highway. Additional roadway capacity scenarios were also modeled, including additional lanes on Loop 375, connectivity between Alameda Ave and Interstate 10 via Old Hueco Tanks Road. The conceptual Border Highway East Extension was also modeled with DynusT to analyze traffic patterns near the Zaragoza and Tornillo ports-of-entry in El Paso County. All scenarios included a tolled corridor on Cesar Chavez Border Highway.
Related Links: PowerPoint slides available by request.
Demand/Access Management
16. Project Title: Dynamic Traffic Assignment for Lake County, California
Location Modeled: Lake County, California
Project Dates: 6/2011 – ongoing
Sponsor: Lake County/City Area Planning Council and Caltrans, District 1
Contact: Jaime Hostler
Application Used: TransModeler (DTA based on microscopic traffic simulation)
Project Description: Caliper is working with Caltrans and area transportation staff to calibrate a model spanning most of Lake County, California. The focus of the model is the management of traffic demand between routes north and south of Clear Lake. The corridor is more than 50 miles in length, is made up of State Routes 20, 29, and 53, and includes considerable local network detail in the towns through which the routes pass. When the model is calibrated and validated, alternative strategies for traffic calming and access management in the towns will be considered with a view to attracting traffic to the route south of the Lake, which impacts local communities to a much lesser degree. At the center of the routing analysis is a microscopic simulation-based dynamic traffic assignment (DTA), which will be used to determine the route choice implications of the various strategies to be studied.
Related Links: PowerPoint slides available by request.
Special Events/Closures/Evacuations
17. Project Title: White House Area Transportation Study
Location Modeled: Core areas of Washington D.C. and Arlington, Virginia
Project Dates: 2005-2010
Sponsor: Federal Highway Administration
Contact: David Roden or Douglas Laird
Application Used: TRANSIMS
Project Description: The White House Area Transportation Study (WHATS) evaluated strategies designed to mitigate the impacts of street closures around the White House on vehicle, pedestrian, and transit travel in downtown Washington D.C. Data from the MWCOG regional model was integrated with TRANSIMS travel simulations to quantify the effectiveness of each strategy. A detailed model was developed, calibrated and validated against observed conditions, and applied for alternatives analysis and evaluation. The first phase of the study evaluated several tunnel configurations under E Street and Pennsylvania Avenue.
The environmental and engineering impacts of these alternatives were identified and construction and impact mitigation costs were estimated. The second phase of the study focused on K Street transitway alternatives and traffic operations strategies. TRANSIMS simulations quantified the highway and transit impacts of these alternatives on individual travelers and the network as a whole. The traffic operations strategies included designating key facilities for travel through and around the White House core and reconfiguring other facilities to support better pedestrian and transit operations.
Related Links: National Capital Planning Commission: Transportation
18. Project Title: Santa Clara County Earthquake Evacuation Simulation Model
Location Modeled: San Francisco Bay Area/Santa Clara County metropolitan area(hybrid/static DTA); Santa Clara County (full DTA and simulation model)
Project Dates: 2009 (pilot study completed)
Sponsor: County of Santa Clara County, California
Contact: Mike Wallace, Fehr and Peers
Application Used: Cube Base, Cube Voyager, Cube Avenue
Project Description: The Santa Clara County (California) Information Services Department, which houses the Emergency Operations Center for Silicon Valley, has performed a number of analyses to evaluate evacuation plans for potential catastrophic seismic events on the San Andreas fault line (i.e., “the Big One”). These included GIS modeling of earthquake damage impacts using FEMA HAZUS-MH software and detailed shelter mapping. The information generated by these GIS-based analyses was combined with data from the Santa Clara Valley Transportation Authority (VTA) and City of San Jose traffic forecasting models to develop strategic models of evacuation travel demand and the effects of potential road network destruction on vehicle traffic generated by uncoordinated self-evacuation attempts. In the course of developing these models, the countywide dynamic traffic assignment and simulation model used in this study was validated against average weekday peak periods conditions and shown to meet and exceed the criteria used to measure the accuracy of the VTA static highway traffic assignment model.
Related Links: Using Cube for Evacuation Planning
19. Project Title: Charles River Bridge Closure Analysis
Location Modeled: Boston and Cambridge, Massachusetts
Project Dates: 2009-2011
Sponsor: Executive Office of Transportation (EOT)
Contact: Mikel Murga, MIT
Application Used: Cube Base, Cube Voyager, Cube Avenue
Project Description: Mikel Murga, a transportation engineering and planning professor at the Massachusetts Institute of Technology, used Cube Avenue to develop a city-wide dynamic traffic assignment model of Cambridge and Boston. The motivation for this model was to research the network traffic effects of policies regarding the closure of bridges across the Charles River. In particular, the DTA and simulation model was able to represent the process of queue formation at intersections and bottlenecks due under alternative network configurations.
Related Links: Policy Implications of DTA and Other Modal Issues
Congestion/Value Pricing
20. Project Title: An Open-Source Dynamic Traffic Assignment Tool for Assessing the Effects of Roadway Pricing and Crash Reduction Strategies on Recurring and Non-Recurring Congestion
Location Modeled: Salt Lake City, Utah, Portland, Oregon, Raleigh, North Carolina
Project Dates: March 1, 2011 to January 1, 2013
Sponsor: FHWA Planning Office
Contact: Brian Gardner
Application Used: DTALite
Project Description: The purpose of this research is to provide transportation planners and engineers with a rigorous and computationally efficient tool to assess corridor and network-wide effects of pricing and crash-reduction strategies on recurring and non-recurring congestion, using performance measures that can be directly applied in investment-level planning and decision-making processes. The research team proposes to build this capability into an open-source dynamic traffic assignment model designed for practical everyday use within the context of an entire large-scale metropolitan area network. The research product will assist state DOTs and regional MPOs to rapidly and systematically examine the effectiveness of traffic mobility, reliability and safety improvement strategies, individually and in combination, for a large-scale regional network, a subarea or a corridor.
Related Links: Network EXplorer for Traffic Analysis (NEXTA) and Light-weight Dynamic Traffic Assignment Engine (DTALite)
21. Project Title: Traffic, Tolling and Financial Analysis Support for Alaskan Way Viaduct and Seawall Replacement Program
Location Modeled: City of Seattle (downtown plus surrounding neighborhoods)
Project Dates: 01/2011 to 12/31/2012
Sponsor: WSDOT
Contact: Chris Wellander or Youssef Dehghani
Application Used: Dynameq (DTA); EMME (Static Model)
Project Description: The objective of this project is to develop a DTA tolling model that more accurately predicts traffic flows and travel times through the SR 99 Alaskan Way Viaduct study area in comparison to the static macroscopic model used in previous analyses. This model will be used to evaluate potential diversion and their impacts; as well as potential toll traffic and associated revenues. Key drivers for development of the DTA tolling model include the heightened concern over diversion impacts from the tolled tunnel; the associated formation of the committee to assess impacts and identify possible mitigation; and the need to develop more realistic estimates of toll traffic revenues.
Factors making the DTA more suitable for these purposes include:
In uncongested conditions, static models produce constant traffic flows that represent the average conditions. In contrast, DTA models produce time-dependent flows that closely follow the observed link or movement volumes.
In congested conditions, static models produce traffic flows that represent the desired link volume and not the one that can actually go through a link. Static models are structurally incapable in constraining flows to not exceed capacities. As a result, in congested conditions unrealistic flows and travel patterns are produced. In contrast, DTA models produce volumes that more closely match the observed values and never exceed capacity.
Dynamic models are significantly more capable than static models in replicating or estimating congestion patterns, bottlenecks, queues, and spillback phenomena.
Dynamic models yield simulated speeds that are much closer to the observed values. This is due to the fact that vehicle simulation is used instead of link-specific analytical functions. DTA models, unlike static ones, capture accelerating, decelerating, merging, and queuing.
Related Links: Washington State Department of Transportation: Alaskan Way Viaduct Replacement Program
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