NSPE TODAY: PROJECT PE
Up in the Air: World’s Tallest Monument Get’s ‘Freq’d’
The Challenge: The 630-foot tall Gateway Arch in St. Louis, which commemorates the nation’s westward expansion, celebrated its 50th anniversary in October. A highlight of any visit to the stainless steel structure is a ride on one of two trams. The eight-capsule trams transport people to and from the spectacular views at the top of the arch every ten minutes.
The trams’ motor-generator sets and most of the related controls, located under the observation deck at the top of the arch, have been in operation since the trams were first placed into service in 1967–68. Replacement of the motor-generator sets and DC motors that hoist and lower the trams along 720 feet of track is necessary to modernize the operation of the trams and clear out much of the confined area under the observation deck.
The trams are operated by Bi-State Development, and the National Park Service maintains the trams. Bi-State, the NPS, and Maida worked together to establish the design concept for this project.
Maida’s work at the arch began in 2005, when it was selected, via qualifications-based selection, to provide a major evaluation and assessment of the tram systems. The Maida team, led by NSPE member Harve Hnatiuk, P.E., F.NSPE, provided what was called the “most complete, thorough study of the trams ever.” In 2007, when a hoist cable broke on the south tram system, Maida was called in to study why the cable failed. An extensive study of this incident included the assistance of RAD Engineering’s Robert DiDomizio, P.E., an NSPE member.
Among the many challenges of working in the arch: very limited spaces, restricted access for large equipment and materials, and working within a triangular space that progressively narrows from the bottom to the top of the arch.
The Solutions: Maida’s design specified new variable frequency drives (VFDs) that will be installed in new drive rooms inside the arch’s legs. The drive rooms will be installed on new platforms that are located about 75 feet from the bottom of the arch.
This upgrade will save energy and facilitate maintenance and operation of the trams. The new drives and their associated controls will be integrated into the tram control system that Maida previously designed to monitor the operation of the trams and control the opening and closing of the landing doors.
Maida’s design will be used by the awarded contractor, who will install the equipment by the spring of 2017. Major construction activity is anticipated this winter.
Specs: Finding a home for the new VFDs and associated control panels was very challenging. There is very little space available at the site for new major equipment. Installation of any equipment under the observation deck was not desirable due to access and clearance issues. Maida, the NPS, and Bi-State worked together to evaluate several options for the locations of the new VFDs. The construction of new platforms inside the arch’s legs is challenging but adds the required “floor space” in a location that can be reached quickly for maintenance and troubleshooting when needed. To that end, the design included a new “stop” at the new platform for each leg’s service elevator, which can be used to transport personnel, equipment and material through the arch’s legs up to 300 vertical feet.
The PE’s Role: The movement of people through the arch needs to be carefully thought out. The public’s safety, health, and welfare must be protected. As such, PEs need to be in charge of a project of this magnitude and significance. Maida’s work on this project was overseen by two professional engineers who are licensed in Missouri and are long-time NSPE members—Joseph Maida, P.E., and Hnatiuk. Mechanical design was provided by Arthur Armellini, P.E., who has worked for Maida for nearly 15 years. Structural engineering/design was provided by Frontenac Engineering of St. Louis. And notably, Bi-State’s project manager, Chance Baragary, is also a P.E.