Technical Information

MITSIMLab is a simulation-based laboratory that was developed for evaluating the impacts of alternative traffic management system designs at the operational level and assisting in subsequent design refinement. Examples of systems that can be evaluated with MITSIMLab include advanced traffic management systems (ATMS) and route guidance systems. MITSIMLab was developed at the MIT Intelligent Transportation Systems (ITS) Program. Professor Moshe Ben-Akiva, Director of the ITS Program at MIT, and Dr. Haris Koutsopoulos, from the Volpe Center, were co-principal investigators in MITSIMLab's development. Dr. Qi Yang, of MIT and Caliper Corporation, was the principal developer.

MITSMLab is a synthesis of a number of different models and has the following characteristics: represents a wide range of traffic management system designs; models the response of drivers to real-time traffic information and controls; and incorporates the dynamic interaction between the traffic management system and the drivers on the network.

The various components of MITSIMLab are organized in three modules:

  1. Microscopic Traffic Simulator (MITSIM)
  2. Traffic Management Simulator (TMS)
  3. Graphical User Interface (GUI)

A microscopic simulation approach, in which movements of individual vehicles are represented, is adopted for modeling traffic flow in the traffic flow simulator (MITSIM). This level of detail is necessary for an evaluation at the operational level. The Traffic Management Simulator (TMS) represents the candidate traffic control and routing logic under evaluation. The control and routing strategies generated by the traffic management module determine the status of the traffic control and route guidance devices. Drivers respond to the various traffic controls and guidance while interacting with each other.

Traffic Flow Simulator (MITSIM). The role of MITSIM is to represent "the world." Traffic and network elements are represented in detail in order to capture the sensitivity of traffic flows to the control and routing strategies. The main elements of MITSIM are:

  • Network Components: The road network, along with the traffic controls and surveillance devices, are represented at the microscopic level. The road network consists of nodes, links, segments (links are divided into segments with uniform geometric characteristics), and lanes.
  • Travel Demand and Route Choice: The traffic simulator accepts as input time-dependent origin to destination (OD) trip tables. These OD tables represent either expected conditions, or are defined as part of a scenario for evaluation. A probabilistic route choice model is used to capture drivers' route choice decisions.
  • Driving Behavior: The origin/destination flows are translated into individual vehicles wishing to enter the network at a specific time. Behavior parameters (such as desired speed, aggressiveness, etc.) and vehicle characteristics are assigned to each vehicle/driver combination. MITSIM moves vehicles according to car-following and lane-changing models. The car-following model captures the response of a driver to conditions ahead as a function of relative speed, headway and other traffic measures. The lane changing model distinguishes between mandatory and discretionary lane changes. Merging, drivers' responses to traffic signals, speed limits, incidents, and toll booths are also captured. Rigorous econometric methods have been developed for the calibration of the various parameters and driving behavior models.

Traffic Management Simulator (TMS). The traffic management simulator mimics the traffic control system under evaluation. A wide range of traffic control and route guidance systems can be evaluated, such as:

  • Ramp control
  • Freeway mainline control
          lane control signs (LCS)
          variable speed limit signs (VSLS)
          portal signals at tunnel entrances (PS)
  • Intersection control
  • Variable Message Signs (VMS)
  • In-vehicle route guidance

TMS has a generic structure that can represent different designs of such systems with logic at varying levels of sophistication (from pre-timed to responsive).

Graphical User Interface (GUI). The simulation laboratory has an extensive graphical user interface that is used for both, debugging purposes and demonstration of traffic impacts through vehicle animation.

 

Application

MITSIMLab is an open-source application where its core models have been written in C++ and are fully available. It has been successfully applied in several traffic and research studies in the USA, the UK, Sweden, Italy, Switzerland, Japan, Korea, Malaysia and Portugal.

 

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