Consulting in the science of buildings, structures and environment

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• Why RWDI
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• A Precedent-setting Approach

  RWDI has consulted on the Boston Central Artery since 1992 and continued for two decades with air quality studies. 

  For this large and ambitious civil engineering project, large portions of Boston’s congested downtown highways and thruways were placed underground.  The project includes the world's widest cable-stayed bridge, the Leonard P. Zakim Bunker Hill Memorial Bridge, for which RWDI applied a full suite of wind engineering services.

  Wind tunnel testing of dispersion from the Boston highway tunnel’s exhaust ventilation buildings was a starting point, but more complex wind tunnel studies would follow. The team also studied how the large numbers of moving vehicles drag air pollutants out of the new tunnels and impact on nearby neighborhoods.

  To simulate and measure the movement of vehicle exhaust exiting from the tunnel portals, tiny cars on a moving belt were mounted in the wind tunnel model. This unique solution was a novel approach to physical modeling of exhaust gases in motion and impressed both the Environmental Protection Agency and the State of Massachusetts, creating approval for a precedent-setting approach. The results of model studies ultimately led to major savings in the cost of the tunnel’s ventilation system when overall exhaust gas impacts were shown to be less than expected.

• Services

  • Air quality - exhaust dispersion
  • Air quality - exhaust re-entrainment
  • Ventilation - effective air distribution
  • Wind engineering - structural loads
  • Wind engineering - wind induced vibration
  • Wind engineering - aerodynamic stability

• Benefits

  RWDI provided innovation: RWDI applied innovation to its wind tunnel testing services to provide clients with increase accuracy. The unique solution impressed both the US Environmental Protection Agency and the State of Massachusetts Department of Environment, creating approval for a precedent-setting approach.  The unique solution involved a high-speed conveyor belt that was used to simulate the air movement associated with moving vehicles.

  Increased accuracy of modeling lead to better exhaust prediction: Exhaust gas impacts were shown to be less than expected.

  Major ventilation system cost savings: The precedent setting approach that increased accuracy of the modeling, resulted in a ventilation system that required lower flow rates and thus cost less.

• Resources

  Boston Central Artery Technote