2024 ACEC Montana Engineering Excellence Honor Award: Cathedral of St. Helena Restoration: Photogrammetry Point Cloud Survey | Cathedral of St. Helena
April 30, 2024
Surveying and Mapping Technologies Award Award
Stahly Engineering aided in restoration of the century-old Cathedral of St. Helena, ensuring its safety and preserving its heritage by providing 3D data and photos for scaffolding design. Restoration addresses damage and wear while protecting original features like tiles and gilded crosses, providing historical and spiritual significance for generations.
The Cathedral of St. Helena is currently undergoing a critical exterior restoration project, addressing both structural and aesthetic concerns of the 100-year-old building. Stahly Engineering & Associates provided initial survey and general engineering services in late fall 2022. Utilizing our point cloud data, contractors designed and quantified scaffolding off-site with precise measurements. Phase 1 scaffold construction, focusing on the south tower, began in late July 2023 with restoration completed in late November 2023. Phase 2 scaffold construction, focusing on the north tower will kickoff early spring of 2024 with restoration complete in mid 2024. The scaffolding contractors assembled the 172-foot-tall, 25-level scaffolding structure on-site, paying special attention to minimizing church accessibility disruptions.
Drone taking off from steps of Cathedral
Stahly Engineering played a vital role, offering Unmanned Aerial Vehicle (UAV) photogrammetry survey, high-definition photography, and point cloud processing to create a 3D model. Stahly also provided engineering support, acting as the Cathedral’s representative to review scaffolding plans, ensuring Cathedral protection during the scaffolding installation. Stahly’s contributions helped facilitate scaffold design and delivery. Moreover, the survey team’s work allowed precise project specifications, streamlining contractor bidding and reducing risk.
Scaffolding was designed off-site and then assembled at the Cathedral.
Restoration efforts include addressing damage from the 1935 earthquake and weather-related wear. This preservation aims to safeguard the Cathedral’s historical character, a Helena landmark. Each original tile, once vulnerable to wind and weather, is being methodically removed, numbered, and cataloged for precise replacement. The reattachment process is fortified using stainless-steel nails, adhesives, and resilient building materials to ensure endurance against high winds.
Remarkably, the century-old wood atop the spire remains well-preserved. At 192 feet, the iconic copper crosses adorning the spires will undergo restoration and re-gilding, restoring them to their former grandeur.
Drone flying over Cathedral capturing point cloud data
““The estimated time savings in having the point cloud reduced scaffold construction time from a couple months to three weeks.” Peter Baker, Montlake Capital – Cathedral Owner’s Rep
This multifaceted project harmoniously combines structural and historical restoration, a testament to the commitment to safeguarding the Cathedral of St. Helena for present and future generations, ensuring it remains a treasure for the Helena community.
