By Dave Pettit, Senior Project Manager, Systems Interface
Washington State Ferries opened its new ferry terminal in Mukilteo, Washington to traffic on December 29, 2020, just in time to bring a happy closing to 2020 and be available to handle traffic for the new year 2021.
Prior to the opening Systems Interface worked with the Washington State Department of Transportation (WSDOT) engineering staff to support the Programmable Logic Controller (PLC) program testing and commissioning for the new passenger overhead Loading (OHL) controls and the Vehicle Transfer Span (VTS) controls for the new facility.
To insure that the controls would work as designed and that the grand opening would go off without a hitch, the PLC and HMI programs were reviewed, modified as needed, and then tested to properly operate both the OHL and VTS systems.
The Vehicle transfer span (VTS) is raised and lowered by two large hydraulic rams, one located on each side of the ramp.
Once the ferry is docked, an operator, using an operator interface terminal, will lower the ramp to the desired height and then lower the apron at the front of the ramp until the apron rests on the ferry. At that point the ramp enters into a "float" mode. When in "float mode" the vehicle transfer span moves up and down with the vessel as vehicles drive off and on the ferry.
The Overhead Loading facility (OHL), which is for passengers, operates in much the same way as the Vehicle transfer span (VTS).
Once the ferry is docked, an operator, using an operator interface terminal, lowers the apron at the front of the ramp until the passenger apron rests on the ferry. At that point the apron enters into a "float mode". As with the Vehicle Transfer Span (VTS), when in "float mode" the passenger apron moves up and down with the vessel as passengers walk off and on the ferry.
In the picture to the left, the two structures are being lowered into place on top of the hydraulic ram located below them. Once in place a walkway will go from the ferry terminal facility and between the two buildings. From an operator Interface Terminal, an operator will raise and lower the entire structure including the ramp and apron which will rest on the upper deck of the ferry.
The building to the left holds the hydraulic pumps and the building to the right holds all the electrical controls and the programmable controller system.
Dave Pettit is a Senior Project Manager at Systems Interface in Mukilteo, Washington.