Browsing by Author "Hourdos, John"

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Access to Destinations: Arterial Data Acquisition and Network-Wide Travel Time Estimation (Phase II)
(Minnesota Department of Transportation, 2010-03) Davis, Gary A.; Hourdos, John; Xiong, Hui; Morris, Ted
The objectives of this project were to (a) produce historic estimates of travel times on Twin-Cities arterials for 1995 and 2005, and (b) develop an initial architecture and database that could, in the future, produce timely estimates of arterial traffic volumes and travel times. Our Phase I field study indicated that on arterial links where both the demand traffic volume and the signal timing are known, model-based estimates of travel time that are on average within 10% of measured values can be obtained. Phase II of this project then focused on applying this approach to the entire Twin Cities arterial system. The Phase II effort divided into three main subtasks: (1) updating estimates of demand traffic volume obtained from a transportation planning model to make them consistent with available volume measurements, (2) collecting information on traffic signal locations in the Twin Cities and compiling this into a geographic database, and (3) combining the updated traffic volumes and signal information to produce link-by-link peak-period travel time estimates. The traffic volume update took as inputs the predicted volumes generated by a traffic assignment model and measured average annual daily traffic from automatic traffic recorders, and gave as output updated estimates of the traffic volumes for links lacking automatic traffic recorders. A request to state, county and municipal agencies in the seven-county metro area produced Information on approximately 2,900 traffic signals. Estimated arterial travel times for the morning and afternoon peak periods for 1995 and 2005 were then computed and sent to other components of the Access to Destinations effort.
Access to Destinations: Twin Cities Metro-wide Traffic Micro-simulation Feasibility Investigation
(Minnesota Department of Transportation, 2008-05) Hourdos, John; Michalopoulos, Panos
The economic importance of effective traffic management becomes more and more evident as traffic demands increase. Faced with the negative effects of traffic congestion including higher transport costs, greater energy consumption, and increased driver delays, transportation agencies around the world areas have responded by building new roads and enhancing their traffic management systems. However, the high costs associated with these projects, and the possibility that improvements in different parts of a complex traffic management system may give rise to unforeseen interactions, have prompted many metropolitan areas to invest in the creation of metro-wide simulation systems that support the evaluation of alternative traffic management scenarios across an entire traffic network. Such undertakings are far from simple; even small-scale microscopic simulations require large amounts of high-quality data. The objectives of this project were to evaluate the feasibility of developing a traffic simulation system for the Minneapolis-St. Paul metropolitan area, and to propose the most appropriate methodology for the design and implementation of such a system, taking into account local needs and capabilities.
Accident Prevention Based on Automatic Detection of Accident Prone Traffic Conditions: Phase I
(University of Minnesota Center for Transportation Studies, 2008-09) Hourdos, John; Garg, Vishnu; Michalopoulos, Panos
Growing concern over traffic safety as well as rising congestion costs have been recently redirecting research effort from the traditional crash detection and clearance reactive traffic management towards online, proactive crash prevention solutions. In this project such a solution, specifically for high crash areas, is explored by identifying the most relevant real time traffic metrics and incorporating them in a crash likelihood estimation model. Unlike earlier attempts, this one is based on a unique detection and surveillance infrastructure deployed on the freeway section experiencing the highest crash rate in the state of Minnesota. This state-of-the-art infrastructure allowed video recording of 110 live crashes, crash related traffic events, as well as contributing factors while simultaneously measuring traffic variables such as individual vehicle speeds and headways over each lane in several places inside the study area. This crash rich database was combined with visual observations and analyzed extensively to identify the most relevant real-time traffic measurements for detecting crash prone conditions and develop an online crash prone conditions model. This model successfully established a relationship between fast evolving real time traffic conditions and the likelihood of a crash. Testing was performed in real time during 10 days not previously used in the model development, under varying weather and traffic conditions.
After Study of The Bus Rapid Transit A Line Impacts
(Center for Transportation Studies, University of Minnesota, 2018-12) Tomhave, Benjamin; Zhang, Yufeng; Khani, Alireza; Hourdos, John; Dirks, Peter; Olsson, Jack; Tao, Tao; Wu, Xinyi; Cao, Jason
In response to the limited awareness surrounding Bus Rapid Transit (BRT) and the A Line, this study provides answers to questions regarding the operation and public perception of the A Line in the Twin Cities region, Minnesota. Two traffic scenarios were studied, one for high-volume oversaturated traffic during the Minnesota State Fair, and a second for normal operating conditions. For both scenarios, intersection queue length and traffic flow rate were compared before and after an A Line bus. It was found that in both time periods (Fair and non- Fair), the dwelling of an A Line bus during a green traffic signal did not have a statistically significant impact on intersection queue length or traffic-flow rate at either of the two researched stations. From an analysis of the 2016 On-Board Survey, it was determined that passengers are more satisfied by the overall service of the A Line than local buses while there is not a significant difference in overall satisfaction compared to express buses, light rail and commuter rail. The top three important service attributes to overall satisfaction are “paying my fare is easy,” “hours of operation,” and “handling of concerns/complaints.” It is recommended that the transit agency improve the attributes that have higher relative influences and lower mean performances. Based on this criterion, the attributes that should be given priority are “shelter/station conditions and cleanliness” and “behaviors of other passengers and atmosphere on board.”
Assessing the Impact of Pedestrian-Activated Crossing Systems
(Minnesota Department of Transportation, 2020-05) Hourdos, John; Dirks, Peter; Lehrke, Derek; Parikh, Gordon; Davis, Gary; Cheong, Christopher
Pedestrian-Activated Crossing (PAC) systems have been shown to have a generally positive impact on driver yield rates. However, there has been insufficient research on the effect PAC treatments have on pedestrian crash rates, and there is little guidance as to when and where each treatment should be used. This study estimates the effects of PACs on pedestrian crash rates using Monte Carlo simulation and examines the relationships between driver yield rates and a variety of treatments and site designs by conducting an observational study using video data from 34 locations. The simulation outcomes suggests that while the percentage of yielding drivers might be a useful indicator of pedestrian level of service, it is less helpful as safety surrogate. This could be because a driver?s yielding to a pedestrian, as observed in field studies, might not be the same behavior as a driver attempting to stop during a vehicle/pedestrian conflict. The observational study shows that the number of lanes to cross at a crossing is positively correlated with the rate at which pedestrians activate the system, but it is not correlated with the delay. Additionally, the study showed that the effect of PAC systems is most pronounced at sites with a higher number of movements conflicting with the crossing or poor visibility from upstream without signs warning drivers of an upcoming crosswalk.
Criteria and Guidelines for Three-Lane Road Design and Operation
(Minnesota Department of Transportation, 2023-02) Davis, Gary A.; Hourdos, John; Gao, Jingru
A 4-3 conversion involves changing a four-lane undivided road into one with two general travel lanes separated by a two-way left turn lane. A commonly-used guideline states that a 4-3 conversion can be considering as long as the road’s average annual daily traffic (AADT) volume does not exceed 15,000 vehicles/day but opinions vary, from lowering the AADT threshold to 10,000 vehicles/day to anecdotal evidence for successful 4-3 conversions with AADTs as high as 20,000. The main objective of this project was to identify conditions where 4-3 conversions might be feasible at AADTs greater than 15,000. After reviewing the literature, we conducted simulation studies on three different roads to identify combinations of major and minor road flow where three-lane configurations provided acceptable levels of service. Eight intersections, with 16 approaches, were then selected to represent our findings. These results were presented as summary tables that practitioners could use to make initial assessments regarding 4-3 conversion feasibility.
Development of a Queue Warning System Utilizing ATM Infrastructure System Development and Field-Testing
(Minnesota Department of Transportation, 2017-06) Hourdos, John; Liu, Zhejun; Dirks, Peter; Liu, Henry X.; Huang, Shihong; Sun, Weili; Xiao, Lin
MnDOT has already deployed an extensive infrastructure for Active Traffic Management (ATM) on I-35W and I-94 with plans to expand on other segments of the Twin Cities freeway network. The ATM system includes intelligent lane control signals (ILCS) spaced every half mile over every lane to warn motorists of incidents or hazards on the roadway ahead. This project developed two separate systems that can identify lane-specific shockwave or queuing conditions on the freeway and use existing ILCS to warn motorists upstream for rear-end collision prevention. The two systems were field tested at two locations in the ATM equipped network that have a high frequency of rear- end collisions. These locations experience significantly different traffic-flow conditions, allowing for the development and testing of two different approaches to the same problem. The I-94 westbound segment in downtown Minneapolis is known for its high crash rate due to rapidly evolving shockwaves while the I-35W southbound segment north of the TH-62 interchange experiences longstanding queues extending into the freeway mainline. The Minnesota Traffic Observatory developed the I-94 Queue Warning system while the University of Michigan, under contract, developed the I-35W system. Prior to the I-94 installation, based on data collected in 2013, there were 11.9 crashes per VMT and 111.8 near crashes per VMT. In the first three months of the system’s deployment, event frequency reduced to 9.34 crashes per million vehicle miles of travel (MVMT) and 51.8 near crashes per MVMT, a 22% decrease in crashes and a 54% decrease in near crashes. The I-35W system did not undergo a similarly thorough evaluation, but for most of the lane segments involved, it showed that queue warning messages help reduce the speed variance near the queue locations and the speed difference between upstream and downstream locations. This also implicated a satisfactory level of compliance rate from travelers.
Development of Guidelines for Permitted Left-Turn Phasing Using Flashing Yellow Arrows.
(Minnesota Department of Transportation, 2015-06) Davis, Gary A.; Hourdos, John; Moshtagh, Vahid
The objective of this project was to develop guidelines for time-of-day use of permitted left-turn phasing, which can then be implemented using flashing yellow arrows (FYA). This required determining how the risk for left-turn crashes varied as traffic-flow conditions varied during the course of a representative day. This was accomplished by developing statistical models, which expressed the risk of occurrence of a left-turn crash during a given hour as a function of the left-turn demand, the opposing traffic volume, and a classification of the approach with respect to the opposing traffic speed limit, the type of left-turn protection, and whether or not opposing left-turn traffic could obstruct sight distance. The models were embedded in a spreadsheet tool which will allow operations personnel to enter, for a candidate intersection approach, existing turning movement counts, and a classification of the approach with respect to speed limit, turn protection, and sight distance issues and receive a prediction of how the risk of left-turn crash occurrence varies throughout the day, relative to a user-specified reference condition.
Development of Next Generation Simulation Models for the Twin Cities Freeway Metro-Wide Simulation Model—Phase 1
(Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2012-10) Hourdos, John
The collapse of the Interstate 35W Highway Bridge over the Mississippi River in Minneapolis resulted in unexpected loss of life and had serious consequences on mobility and accessibility in the Twin Cities metropolitan area. In response to the network disruption caused by the bridge collapse, a number of traffic restoration projects were proposed and implemented by MnDOT in a very short order. Selection and prioritization of these projects, however, was mainly based on engineering judgment and experience. The only decision-support tool available to traffic engineers was the regional transportation planning model, which is static in nature and decennial. Although such a model is suitable for the evaluation of long-term (in the order of 5 years or longer) transportation investments, it is not appropriate or adequate for short-term (within days or weeks) operational planning in response to a disaster or other emergencies. This was the driving force behind the creation of a comprehensive model of the Twin Cities freeway and major highway system that can support higher levels of traffic simulation resolution. Phase 1, described in this report, of the development of the Twin Cities metro-wide freeway microscopic model covered the importation of the roadway geometry into a microscopic simulator, generation of demand information for the entire model as well as for the calibration of as many as possible individual segments. In total, 1,199 directional kilometers of freeway mainline where included in the model. Including ramps and major highways, the number rises to 2,492 directional kilometers. The demand in the model is generated from 859 zones extracted from the regional planning model.
Development of Real-Time Traffic Adaptive Crash Reduction Measures for the Westbound I-94/35W Commons Section
(University of Minnesota Center for Transportation Studies, 2008-12) Hourdos, John; Xin, Wuping; Michalopoulos, Panos
Much research has been conducted in the development, implementation, and evaluation of innovative ITS technologies aiming to improve traffic operations and driving safety. An earlier project succeeded in supporting the hypothesis that certain traffic conditions are favorable to crashes and in developing real-time algorithms for the estimation of crash probability from detector measurements. Following this accomplishment a natural question is “how can this help prevent crashes?” This project has the ambitious plan of not only answering this question but also providing a multifaceted approach that can offer different types of solutions to an agency aimed at reducing crashes in this and other similar locations. This project has two major objectives; first it aimed at utilizing a cutting edge 3D virtual reality system to design and visualize different driver warning systems specifically for the I-94 westbound high crash location in Minneapolis, MN. Second, in view of the desire of local engineers for a more traditional approach, this project explored the use of existing micro-simulation models in the evaluation of safety improvements for the aforementioned high crash area. This report describes the results of these investigations but more importantly describes the lessons learned in the process of the research. These lessons are important because they highlight gaps of technology and knowledge that hampered this and other research projects with similar objectives.
Directional Sound for Long Distance Auditory Warnings from a Highway Construction Work Zone
(University of Minnesota Center for Transportation Studies, 2008-12) Phanomchoeng, Gridsada; Rajamani, Rajesh; Hourdos, John
Directional sound can be used as a warning signal to denote that failure to follow an indicated action could result in serious accidents. In some applications such as to alert a vehicle that is likely to intrude into a highway construction work zone, long distance auditory warnings are necessary. In such cases, directed sound could be utilized to warn the specific vehicle without disturbing other vehicles on the highway. This report reviews the currently available scientific technologies that can potentially be used to develop a long distance auditory warning system for highway work zone applications. Of these, ultrasound based parameter arrays and time delay controlled arrays of compact ordinary speakers are taken up for detailed analysis and experimental evaluation. An ultrasound based parametric array is the most appropriate technology for generating highly directional sound. However, if cost, installation, maintenance, and price are considered, the most suitable technology is found to be arrays of flat panel loudspeakers with time delay control. Such a system can be used to generate directional sound effectively for long distance auditory warnings.
Effect of Signing and Lane Markings on the Safety of a Two-Lane Roundabout
(Minnesota Department of Transportation, 2014-01) Hourdos, John; Richfield, Veronica; Acosta, Luzcenit
This report presents a study of the impact lane markings and signing have on driving behavior at a two-lane roundabout located in Richfield, Minnesota. After its completion in 2008, this roundabout sustained a suspiciously high amount of crashes. In response, through this study, engineers experimented with changes in the roundabout’s signs and lane markings, as roundabout design regulations are relatively lax and nonspecific in contrast to those for standard signalized intersections. An observational study was conducted that reduced 216 hours of before and after video records of the roundabout into a database of all the violations committed by drivers. Along with the observational data, crash records were analyzed and demonstrated that improper turns and failing to properly yield account for the majority of collisions. The changes implemented in the approaches to the roundabout and specifically the extension of the solid line seems to have reinforced the message to the drivers that they must select the correct lane before approaching the roundabout entrance. Although choosing the correct lane does not directly address yielding violations, it does reduce the occurrence of drivers conducting an improper turn and to some extent reduces the need for a driver to change lanes within the roundabout. The implemented changes produced a 48% reduction in normalized occurrences of improper turns, and a 53% reduction in normalized occurrences of drivers choosing the incorrect lane a month after the changes, while a year later, these reductions were 44% and 50%, respectively.
Effectiveness of Urban Partnership Agreement Traffic Operations Measures in the I-35W Corridor
(Intelligent Transportation Systems Institute, Center for Transportation Studies, 2013-08) Hourdos, John; Abou, Seraphin Chally; Zitzow, Stephen
One of the leading transportation project initiatives of the Minnesota Department of Transportation (MnDOT) is to reduce transportation system congestion. The Minneapolis Urban Partnership Agreement (UPA) project is one of the five major projects funded by the U.S. DOT’s Strategy to Reduce Congestion on America's Transportation Network. Minnesota’s UPA is concerned with Active Traffic Management (ATM) systems along I-35W from the southern junction with I-35 to downtown Minneapolis (which will be referred to as the UPA corridor). Three separate but related evaluations are included in this UPA related project: the effects of the variable speed limit (VSL) system on congestion and driver behavior, the impact of severe weather conditions on road safety, and the behavior of bus rapid transit (BRT) vehicles and their impacts on traffic conditions between 46th Street and Lake Street.
Employment of the Traffic Management Lab for the Evaluation and Improvement of Stratified Metering Algorithm - Phase III
(Minnesota Department of Transportation, Research Services Section, 2007-05) Liu, Henry; Wu, Xinkai; Michalopoulos, Panos; Hourdos, John
The evaluation results (done in Phase II) demonstrated that the SZM strategy was generally beneficial. However, they also revealed that freeway performance degraded by reducing the ramp delays. Therefore, it is desired to improve the effectiveness of the current SZM control. There are two objectives in this study. One objective is to improve the control logic of current SZM strategy. This is accomplished through an estimation algorithm for the refined minimum release rate. The simulation results indicate that the improved SZM strategy is very effective in postponing and decreasing freeway congestion while resulting in smoother freeway traffic flow compared to the SZM strategy. The second objective of this project is to improve the current queue size estimation. Depending on the counting error of queue and passage detectors, freeway ramps are classified into three different categories, and different methods are applied respectively for improved queue size estimation. The surveillance video data were recorded and used to verify the improvement of the proposed methods. The results indicate that the proposed methods can greatly improve the accuracy of queue size estimation compared with the current methodology. Also, the proposed method was evaluated by the micro-simulation. The simulation results indicate the performance of freeway mainline is significantly improved. And the total system performance is better than the original SZM control.
Employment of the Traffic Management Lab for the Evaluation and Improvement of Stratified Metering Algorithm - Phase IV
(Minnesota Department of Transportation, 2007-12) Liu, Henry; Wu, Xinkai; Michalopoulos, Panos; Hourdos, John
Freeway ramp control has been successfully implemented since mid 60's, as an efficient and viable freeway management strategy. However, the effectiveness of any ramp control strategy is largely dependent on optimum parameter values which are preferably determined prior to deployment. This is certainly the case happening to the current Stratified Zone Metering (SZM) strategy deployed in the 260 miles freeway network of Minneapolis - St. Paul metropolitan area. In order to improve the performance of the SZM, which highly depends on the values of more than 20 parameters, this research first proposed a general methodology for site-specific performance optimization of ramp control strategies using a microscopic simulation environment, as an alternative to trial and error field experimentation, and implemented the methodology to the SZM. The testing results show that the new SZM control with site-specific optimum parameter values significantly improves the performance of freeway system compared with the original SZM strategy. Secondly, this research proposed a methodology to explore the common optimum parameter values for the current SZM strategy for the whole Twin Cities freeway system, in order to replace the site-specific optimum values which have minor practical value because of the difficulties in implementation and numerous time-consumption to search the site-specific optimum values for all the freeway sections. The common parameter values are identified applying the Response Surface Methodology (RSM) based on 4 specifically selected freeway sections which can represent all types of freeway sections in Minneapolis-St. Paul metropolitan area.
Enhanced Micro-Simulation Models for Accurate Safety Assessment of Traffic Management ITS Solutions
(University of Minnesota Center for Transportation Studies, 2008-11) Xin, Wuping; Hourdos, John; Michalopoulos, Panos
Much research has been conducted in the development, implementation, and evaluation of innovative ITS technologies aiming to improve traffic operations and driving safety. Existing micro-simulation modeling only describes normative car-following behaviors devoid of weakness and risks associated with real-life everyday driving. This research aims to develop a new behavioral car-following model that is pertinent to the true nature of everyday human driving. Unlike traditional car-following models that deliberately prohibit vehicle collisions, this new model builds upon multi-disciplinary findings explicitly taking into account perceptual thresholds, judgment errors, anisotropy of reaction times and driver inattention, in order to replicate “less-than-perfect” driving behavior with all its weakness and risks. Most importantly, all parameters of this model have direct physical meaning; this ensures vehicle collisions are replicated as a result of behavioral patterns rather than simply being numerical artifacts of the model. Meanwhile, vehicle trajectories were extracted from real-life crashes collected from a freeway section of I-94WB This is by far the first data collection efforts that aim to collect vehicle trajectories from real-life crashes to aid car-following modeling. These data were employed in this study to test, calibrate and validate the model. This new model is successful in replicating these vehicle trajectories as well as crashes.
Enriched Sensor Data for Enhanced Bridge Weigh-in-Motion (eBWIM) Applications
(Center for Transportation Studies, 2018-11) Kumar, Ravi; Schultz, Arturo; Hourdos, John
Bridge weigh-in-motion (BWIM) systems, which measure bridge deformation under live loading to estimate weights of passing vehicles, have been in development since Moses first introduced the concept in 1979. Despite advances made since its introduction, important limitations for BWIM systems still exist. A feasibility study was performed to determine if some of the limitations—including poor accuracy with multiple vehicle passage, either in tandem or side-by-side; and inability to accurately capture the passage of a vehicle moving at variable speeds—could be overcome by enriching the dataset available to the BWIM system. Non-contact measurements collected in real time on the topside of the bridge can enrich the dataset, and by taking advantage of these measurements a more accurate and effective enriched bridge weigh-in-motion (eBWIM) system can be developed. Several sensing technologies were reviewed including fiber Bragg gratings, MEMS accelerometers, microwave radar sensors, magnetic sensors, active infrared detectors, and video image vehicle detection systems. Preliminary results indicated that there was no clear candidate for a fully mature sensing system that would satisfy all the criteria in this study. However, microwave radar sensors have a reasonably low cost, are the least intrusive, and perform better in all weather conditions compared to the other sensors. A testbed using radar sensors is proposed to investigate the accuracy of the eBWIM system. If the desired accuracy of the eBWIM system can be achieved, its implementations should prove to be invaluable for enforcing bridge weight limits, studying truck traffic patterns, and managing bridge inventories.
Estimating Running Time and Demand for a Bus Rapid Transit Corridor
(University of Minnesota Center for Transportation Studies, 2009-12) Horning, Jessica; El-Geneidy, Ahmed M.; Hourdos, John
Due to the increasing ease and affordability of intelligent transportation systems (ITS) data collection, new methods for assessing conditions along current and future transit corridors are available. Measures such as average speed, travel time, and intersection delay can be determined for car and bus traffic along a corridor using readily available technology. These measures can be used to monitor the performance of the transportation system for existing modes and to estimate measures for proposed additions to the system. The goal of this research is to utilize GPS device records from regular vehicles as well as busses to estimate running time and potential passenger demand for a proposed Bus Rapid Transit (BRT) corridor on Cedar Avenue in the southern Twin Cities Metropolitan Area. Demand for future BRT service is predicted based on frequency and reliability of service and socio-demographic characteristics of the region around the corridor. Average passenger counts for existing transit service along the corridor in combination with existing commuting patterns in the region are used to estimate passenger demand. The running time and demand models produced by this study can be integrated with existing cost benefit software to evaluate the effects of intelligent transportation systems technologies on BRT running time (IBAT). The findings of this research introduce a benchmark for comparison between transit and private vehicle running time for general applications in Hennepin County. These findings also help to create additional understanding of the potential for BRT service in the Twin Cities region.
Estimating the Crash Reduction and Vehicle Dynamics Effects of Flashing LED Stop Signs
(Minnesota Department of Transportation, 2014-01) Davis, Gary A.; Hourdos, John; Xiong, Hui
A flashing LED stop sign is essentially a normal octagonal stop sign with light emitted diodes (LED) on the stop sign’s corners. A hierarchical Bayes observational before/after study found an estimated reduction of about 41.5% in right-angle crashes, but with 95% confidence this reduction could be anywhere between 0% and 70.8%. In a field study, portable video equipment was used to record vehicle approaches at an intersection before and after installation of flashing LED stop signs. After installing the flashing stop signs, there was no change in the relative proportion of clear stops to clear non-stops when minor approach drivers did not face opposing traffic, but the relative proportion of clear stops increased for drivers who did encounter opposing traffic. Random samples of 60 minor approach vehicles were selected before and after installation of flashing LED stop signs and speeds for these vehicles when about 500 feet from the intersection, and average deceleration rates over the final 500 feet, were estimated using trajectory-based methods. Average approach speeds tended to be highest in June, somewhat lower in July, and lower yet in September and November, with September and November having roughly equal average speeds. The average deceleration rates showed a similar pattern.
Evaluating Twin Cities Transitways’ Performance and their Interaction with Traffic on Neighboring Major Roads
(Center for Transportation Studies, University of Minnesota, 2015-03) Hourdos, John; Lehrke, Derek
Long-term, regional travel demand models are essential tools used by planning organizations for resource management, project scheduling, and impact studies. Developed primarily at the macroscopic level, these tools lack sufficient detail to capture the influence of local geometry, dynamic traffic controls, or advanced transportation demand management (ATDM) strategies. To bridge the gap, a hybrid mesoscopic-microscopic model was developed. The core of the model, surrounding two light rail corridors in Minneapolis-Saint Paul, Minnesota, was developed at high resolution for microscopic simulation to capture the interaction between traffic signals, transit systems, and the road network. The remainder of the greater Twin Cities area was implemented based on the Regional Planning Model (RPM) maintained by the Metropolitan Council. Interfacing the Aimsun-based hybrid model with the Cube-based RPM, the Twin Cities Metro Hybrid Simulation was used to iteratively improve mode choice and traffic assignment to achieve a dynamic user equilibrium state. Important lessons were learned regarding the effort required to develop and maintain such a model with implications for future large scale regional modelling.

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