Dynamic Traffic Assignment Model

Benefits of a DTA model

I-5DTAextentThe major benefit of Dynamic Traffic Assignment (DTA) models, compared to the traditional 4-step travel demand model, is the ability to simulate how drivers interact to congestion and how they respond. The DTA model is capable of reading all file formats and data structures of the regional Emme Travel Demand Model (TDM), and shares common zonal system, network, and travel demand.

The dynamic traffic assignment moves individual vehicles on lanes, with car-following models, gap-acceptance models, and explicit signal timings. In terms of scale, the regional DTA model fits in between the regional macro model and micro simulation models and is often referred to as a mesoscopic model. It enables modeling of:

  • Signal timing strategies,
  • Identification (place, and duration) and impacts of bottlenecks,
  • Intersection/roadway levels of service,
  • Intersection queuing of vehicles, and 
  • Vehicle propagation throughout the network

Features can be modeled on a minute by minute basis, or user defined period such as the peak hour. With this greater detail in traffic simulation, the DTA also provides more detailed measures of roadway performance enhancing transportation planning and analysis.

With a close linkage to the TDM model, efficient exchange of information allows for measuring the impacts of mode choice on the roadway systems performance.

DTA models are suitable for analyses involving:

  • Incidents and construction zones,
  • Active transportation and demand management strategies,
  • Integrated corridor management strategies, including traffic signal synchronization
  • Intelligent Transportation Systems (ITS), and other operational strategies
  • Capacity increasing strategies, such as new connections, intersection treatments, addition of turn lanes, or access control

Regional DTA Model (I-5 Model) 2019 Documentation