Client: New York City Department of Transportation (NYCDOT) with Cambridge Systematics and STV.
Brief: Set up a high quality large-scale simulation model of Manhattan and its immediate peripheral arterials.
The Manhattan Traffic Model (MTM) is one of the most complex large-scale simulation models in existence. It came about in response to the complexities of traffic enforcement, managed use lanes, traffic signal coordination, various bridges and tunnels connecting Manhattan to other New York boroughs and New Jersey, and the disruption of various major construction projects dotting the network.
The aim was to build an analytical tool that would permit the consistent assessment of the network-wide cumulative impact of current and future traffic management projects. In the long term, the base network will be the platform for future analyses and expansion to other boroughs and, where possible, the region.
The current model has a microscopic core between 16th St and 66th St set within a mesoscopic model stretching from the tip of lower Manhattan up to 179th St, including major links in Eastern New Jersey, Queens and Brooklyn. The entire model covers over 2,800 miles of lanes, 1,583 centroids/zones, and millions of private vehicle trips throughout the day.
The initial trip table for the mesoscopic study area was extracted from the city’s original BPM and then adjusted to reflect more detailed traffic counts in the project area using a series of Origin-Destination Matrix Estimation (ODME) techniques, ranging from proportional fitting to sophisticated linear programs. The challenge was to keep the data and calculations consistent between the BPM and the dynamic model.
The MTM includes all applicable traffic signal plans and hour-by-hour information on parking and turning regulations as well as incorporating curbside observations such as the presence of stopped and double-parked vehicles. The model also includes three scenarios: morning, midday and evening – each consisting of millions of trips – in which drivers select routes in accordance with a generalised equilibrium principle.
An important innovation is the software’s ability to use the current equilibrium as the initial routes of future scenarios. This way, when something is changed, the drivers do not lose the experience gained up until that point and are simply adapting to the new conditions, just as they would in real life.
NYCDOT is working with other regional agencies to coordinate modelling activities where the MTM network will be used 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 on a sustainable regional model.
The first of the studies to use the MTM is a Transit Signal Priority (TSP) project, which aims to quantify the improvements in the bus service with the introduction of signal priority for buses on the 34th street corridor.