Empire State Plaza Grand Staircase Laser Scan Survey

laser scanning of Albany buildings done by C.T. Male Associates
aerial view of Empire State Plaza Grand Staircase laser scan survey
award winning high def 3d laser scan of empire state plaza steps
C.T. Male Land Surveyor scanning a project at Empire State Plaza

Albany, New York

American Council of Engineering Companies New York (ACEC) Gold Award for Surveying and Mapping technology for the Empire State Plaza Grand Staircase Laser Scan Survey in Albany, New York.

The steps which lead from the Empire State Plaza to the New York State Museum in Albany, NY are known as the “Empire State Plaza Grand Staircase.” As surveyors, we are history buffs and spend a great deal of time researching old documents which are contained in the museum. This wealth of historical records date back over three hundred years, to when New York State was first founded in 1788. The museum also holds countless pieces of historical surveying equipment from the same era. It is fitting that just outside the doors of the museum, which serves as home to some of the oldest survey equipment in New York, C.T. Male Associates was retained to perform a new survey, using state of the art technology like high definition 3D laser scanners and high powered computers.

In April 2014, C. T. Male Associates Engineering, Surveying, Architecture & Landscape Architecture, D.P.C. (C.T. Male Associates) was retained to assist Allegone Masonry in the repairs of the Empire State Plaza Grand Staircase. The New York State Office of General Services hired Allegone Masonry, a company that specializes in masonry preservation, to complete repairs.

The Empire State Plaza was constructed between 1959 and 1976; the complex’s basic design was conceived by then Governor Nelson Rockefeller and architect Wallace Harrison. The Plaza was designed to complement the Albany skyline from across the river. The Grand Staircase is a master piece of architectural and engineering prowess, providing both form and function as a grand entrance to the Cultural Education Center, a bridge over Madison Avenue, and amphitheater style seating for summer concerts, fireworks and other public events on the south plaza. Located on the south end of the plaza and leading up to the Cultural Education Center and New York State Museum, it provides a pedestrian bridge over busy Madison Avenue.

Over the past 40 years the state employees, visitors and residents of New York’s Capital Region area have enjoyed the use of this staircase as a place to sit and eat their lunch on a summer’s day. Through the years, the open air staircase developed cracks in the joints, broken pieces and settlement in the treads and benches, causing leaks and water damage to the structure. The reconstruction project requires the complete removal and storage of the 2,262 granite stair treads, benches, light benches and footwells, along with marble cheek walls, coping stones and balustrade. Old waterproofing will be removed and replaced, all 172 light benches will have the old light fixtures removed and newly constructed stainless steel fixtures attached along with new hand railings. All granite and marble components will be reinstalled to their original positions. The staircase consists of three flights each being forty-nine feet long with an eight foot landing. It is divided into six sections with each sections being sixty-five feet wide have twenty-nine treads and fourteen benches. Each bench is forty feet long consisting of eight 4’-9 ¼”x 1-’9”x 4” sections of granite. The staircase was originally designed in six sections leading Allegone Masonry to decide to repair the staircase in keeping with the original six sections to ensure the weight differential incurred from deconstruction and reconstruction would not compromise the structure. The weight of each stone is factored into the structural stability of the span.

The project is being completed in stages over the course of a two year period with an estimated completion date of April 2016.

State of the art surveying technology, known as Terrestrial LiDAR 3D Laser Scanning, is being utilized to map the existing horizontal and vertical positions of all steps and benches. The high-definition 3D Laser collects high-density spatial imaging data by creating millions of coordinates with extremely high accuracy. The entire 163 feet wide x 130 feet long staircase was scanned to reveal the condition and location of each joint and stone. A site plan was then prepared providing distances from the outer marble wall to the far side of each granite stone. Four elevations were also provided for each granite stone to determine the amount of tip and tilt of each stone.

A Project Execution Plan was prepared for the positioning of the laser scanner to maximize data collection and to ensure the locations of each of the joints, treads, lighting and hand rails were accurately mapped. Horizontal and vertical control was established using Global Positioning Systems (GPS) and other survey methods including robotic instrumentation before scanning started. The scanning of the entire staircase was then completed over a period of two days, with 33 scan setups. Laser scanning technology collects 50,000 data points per second, with an accuracy of 1.5 mm. The technology creates high resolution, detailed mapping that far exceeds what can be produced by traditional survey measuring techniques. Nearly 285 million data points were collected over the entire structure. Each scan created a point cloud consisting of data in 360º horizontally and 270º vertically along with georeferenced panoramic color photos.

The results of the laser scan produced an accurate record survey allowing us to compare the original construction drawing to the existing conditions. The comparison outlined where each bench had settled and tipped. This information was used to further to make certain that Allegone was able to rebuild the staircase in its original form. The processing of the scanner data and existing conditions mapping was completed within a matter of days allowing for Allegone Masonry to quickly submit their work plan to The Office of General Services for approval.

During the course of the project the data was reviewed several times to identify important measurements that were not obtained or mapped during the initial work. This would not have been possible if conventional methods were used to obtain measurements.  Once the granite was removed it would not have been possible to re-measure critical distances. One example of this was when it came time for Allegone Masonry to re-install the new handrails. With the scan data we were able to revisit the scan data virtually and compute were the existing post holes were located before they were covered with the new stone. This allowed Allegone to re-drill the hole in the correct locations and re-install the handrail to exacting tolerances.

A thorough understanding of the complex processing and mapping software enabled us to conceive an adaptive and innovative use of the scan data. 3D images were rotated so that measurements of all the features of the staircase could be determined and mapped to provide the horizontal and vertical location, allowing the Contractor to be certain that the staircase is rebuilt to its original form.

The use of this technology provided a level of detail that could not otherwise have been obtained.

Moving forward, we will continue to utilize the 3D laser scan technology to ensure that the reconditioned steps and benches are replaced in their original locations with corrections for tip and tilt and 40 years of harsh Upstate New York weather. After completion, the public will be able to enjoy this masterpiece of architecture for another 40 years.

The total budget for the project is $6,700,000.00. CT Male Associates’ total fee for the project was $45,000.00 with the existing conditions survey scan totaling $15,300.00. Additional field visits were made after the initial data collection and during construction to stake proposed stone elevations and for a final record survey after construction.

CT Male Associates has continued the use this technology over the past eleven years. We consistently upgrade our equipment and software, ensuring to stay current with the ever-changing technology. We have trained all our survey personnel and technicians to operate and use it on our daily operation. It has been most helpful in reducing return trips to project sites and being able to return to the data in a virtual way when the existing conditions no longer exist.

Someday 3D Laser Scanners will be obsolete and placed in the New York State Museum as another tool in the surveyor’s ever-changing toolbox. Until that time 3D Scanning technology remains a valuable and cutting-edge tool to help restore aging infrastructure, restoring it to its original magnificence.

For more information about this project, or to speak with member of C.T. Male Associates’ survey division and learn more about our surveying capabilities, please contact us today at 518-786-7400 or complete our quick and easy contact form.