‘Simulation in action at work zones’

ITS International, May/June 2013

Satya Muthuswamy of KLD Companies describes the practical application of Aimsun for traffic management in an award-winning NYCDOT project near the Queensboro Bridge in New York City:

Traffic management during the construction of a new water tunnel close to the Queensboro Bridge in New York City involved a contraflow on the bridge approach, street closures and a detour route. These diversionary plans were evaluated before implementation. The US$210,000 project for the New York City Department of Transportation, with KLD as contractor, combined traffic engineering and simulation. The latter confirming the engineering analyses for assurance of the proposed maintenance and protection of traffic (MPT) plan.

Field conditions posed several challenges in developing the simulation model. Among these, several intersections on the bridge approach have traffic enforcement agents to prevent gridlock and when conditions permit, advance vehicles can override signal settings and alter vehicle discharge characteristics.

The solution involved:

  • Use of Aimsun’s ‘sunshine control’ or ‘yellow box’ feature in the simulation model to avoid gridlock, by preventing vehicles entering an intersection unless gaps were long enough to allow them to clear it
  • Adjustment of vehicle behaviour parameters inside the ‘yellow box’ to reflect field discharge rates at stop lines

One bonus was that 66 days of continuous volume data for the bridge was available for the analysis making it possible to reliably identify the bridge’s capacity.

Aside from calibration issues, the turning radii of large trucks and buses detouring to the contraflow required special attention using AutoTURN turn simulation and AutoCAD computer aided design software. When larger vehicles were seen to use the middle of three lanes on 58th Street to enter the contraflow, the stop lines were adjusted to accommodate them.

The combined solution was of material help in finalising the operating configurations for the MPT plan – specifically the contraflow element.

The project has received an American Council of Engineering Companies (ACEC) national recognition award.

www.nyc.gov/dot www.kldcompanies.com www.autoturn.com

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© 2013 Reproduced with kind permission from Route One Publishing Ltd, with supplementary images provided by KLD Companies.