Workin’ on the Railroad
Amberg Technologies’ laser scanning trolley systems and software suite make this New York City subway extension project easier.
RailWorks was pleased with the results. “By deploying Maser Consulting and their expertise with their Amberg Rail trolley, we were able to dramatically improve our response to any clearance issues well in advance of our client’s inspection,” says Jeffrey Nalbone, project manager for RailWorks Transit. “Coupling Maser’s work with our own Amberg trolley work with track alignment just made the whole process that much more seamless.”
Instead of traditional railroad timber ties, the No. 7 extension utilizes a low vibration track (LVT) system. Due to tight deadlines and the precision required to maintain vertical and horizontal clearances within the tunnel, Maser Consulting performed additional scans for as-built track alignment and geometry prior to setting the LVT blocks to concrete. This was done to ensure that the top of the rail was set at a certain distance below the proposed top of the rail elevation, to accommodate the rise of the LVT’s as the concrete slab cures. Particular focus was made on the alignment, super-elevations and gauge. Dynamic clearance cross-sections were then developed, providing added assurance that MTA clearance specifications were met.
After track adjustments were made during the concrete pour, the Amberg GRP 1000 configuration (without the laser scanner) was used to align the left and right rails of the track to its proper position. The Amberg GRP 1000 closely follows the hopper as it is moved into position. As the concrete is poured, the system is rolled 6 to 10 feet, where track adjustments are made. At each stop, the trolley operator tells laborers the exact alignment of each rail by utilizing Amberg Slab Track software.
“The No. 7 extension tunnel is a prime example of a project where fusion of point-cloud data and track measurements were collected simultaneously with one specific tool, where multiple technologies were incorporated to perform routine tasks common to rail construction,” Leonard says. “Tunnel or no tunnel, the Amberg method, combined with a fundamental and technological approach to precise land surveying techniques, creates value on any rail project in terms of the time and speed in which data is collected, its precision and with the various types of deliverables we can generate for project owners.”
Through Amberg Rail software, dynamic clearance analysis was developed using the MTA’s A Division car-body clearance specifications. The car body was created in Autodesk AutoCAD and imported into Amberg Rail. Cross-sections were developed at 10-foot intervals along tangent track and at 5-foot intervals along curves. That information was provided to RailWorks Transit, so that it could identify potential obstructions along the tunnel wall and ledges, such as conduits, signals or the wall itself. In addition, a spreadsheet of all pertinent track geometry was developed, including alignment, top of rail, gauge and super-elevations, as well as an ASCII point file of critical tunnel asset locations.
These cross-sections were created with and without “bandwidth” (forward scanning and back scanning of the actual measures profile location at a defined distance). Users can extract the sections at any possible interval. These cross-sections depict distances from the selected shape (as defined by the created MTA clearance model) to the surrounding actual features as measured by the scanner. The cross-sections can be exported in a variety of formats, including Adobe PDF and Autodesk DXF.
The Amberg project was then processed for 3D deliverables, including point-cloud data in .PTS format, which is then converted to an .LAS format using third-party software. Scans performed using the Amberg TMS position method were processed with Amberg TMS Office, the same as the deliverables generated from Amberg Rail.
“The Amberg Rail suite is a fantastic tool when it comes to processing accurate track data and performing clearance analysis,” says CJ Ruch, Maser Consulting’s project surveyor. “Raw data processing times can be quicker, but no other software can provide the end result like Amberg Rail can, in terms of providing track detail and dynamic clearance analysis. ... When there’s 12,000 feet of track and tunnel to process, that’s a lot cross-sections. Who’s got time for that? I know we don’t.”