Workin’ on the Railroad
Amberg Technologies’ laser scanning trolley systems and software suite make this New York City subway extension project easier.
While there are many technologies and services used to acquire critical data associated with railways and their rights-of-ways, some can be cumbersome and require logistical challenges that can increase risk to track workers. Maser Consulting P.A., a multidisciplined engineering and land surveying firm with offices throughout the East Coast and Mid-Atlantic and with projects located nationally, employs Amberg Technologies, a provider of specialized systems for the georeferenced collection and refinement of civil infrastructure information to alleviate that risk.
Maser Consulting used Amberg’s GRP 5000 and GRP 1000 trolley systems with 3D laser scanners mounted on them to acquire LiDAR data of continuous railroad geometry and tunnel appurtenances on the No. 7 subway line in New York City recently.
Designed for direct contact with the tracks, Amberg’s trolley and software solutions provide comprehensive track geometry and corridor mapping, including gauge, super-elevation, curvature, middle ordinate, clearance and asset inventory. Designed like a three-wheel trolley and weighing 45 pounds, a single operator can exit the tracks with the Amberg GRP 5000 system in seconds. This mobile system increases safety and reduce the duration of track outages and the need for lengthy mobilization times.
“When time is of the essence, the Amberg method is a … profound tool that gives us the ability to provide our clients (with) a comprehensive and accurate solution in an efficient and cost-effective manner,” says Ryan Leonard, a Maser Consulting rail and tunnel consultant.
The trolley at its core is a geometric measuring sensor. Positional information is established by a robotic total station located by resection to the local control monuments, which is continuously tracking a prism mounted on the trolley. With the inclusion of a phase-based 3D laser scanner, the Amberg trolley captures continuous LiDAR data perpendicularly about the tracks, reaching as far as 79 meters. The complete dataset is then geographically referenced to the local control using the Amberg Rail software suite.
Utilizing a Leica TS30 for position, a Z+F 5006i laser scanner and a Panasonic Toughbook to run the Amberg software, Maser Consulting’s crews can capture comprehensive track geometry and LiDAR information at more than 600 feet per hour. Within tunnel environments, data is gathered at an average speed of 0.5 miles per hour.
One problem that must be overcome is the position of the laser scanner. Due to its position mounted on the trolley, features inside the rails cannot be collected. Static or stationary laser scanning methods can be implemented to gather this information. This technique has been successfully and extensively used on New York City and Washington, D.C., area rail and tunnel projects.
“Different projects require different tools. The same scanner can’t be used on every project,” said John Ott, Maser Consulting’s crew chief. “Due to the level of detail that the client required, especially in subway tunnel construction, accurate track measurements (were) obtained using the Amberg trolley system, not only because of its ability to collect precise rail data in real time, but how quickly we can collect it. … If you want dynamic clearance and track data, Amberg’s the one you want. The true benefit is realized when the data we collected is processed using the Amberg Rail suite in the office. Time savings in that aspect is substantial.”
Under construction since 2006, the No. 7 subway line, which had terminated at Times Square, is being extended approximately one mile to a new station at 34th Street and 11th Avenue. Upon completion, the $2.4 billion extension will provide access to the entire Hudson Yards Redevelopment area and is vital to the growth of businesses and to residents on the Far West Side of Manhattan.
Hudson Yard currently serves as the Metro Transit Authority’s 20-acre western rail yard, where the MTA has leased the rights to developers to create New York City’s largest development project in recent years. Proposed development includes a 14-acre park and 16 skyscrapers, containing approximately 13 million square feet of commercial, retail and residential space.
In February 2013, as part of the track and signal contract issued to RailWorks Transit, a division of New York City-based RailWorks Corp., Maser Consulting performed as-builts of approximately 12,000 linear feet of track, including two tangential crossovers and a station platform at 34th Street. RailWorks chose Maser Consulting due to its ability to generate clearance as-builts without the need for a geometry car or plywood cutouts of train body cross-sections.
For existing tracks, resections using a minimum of four points were used to establish the position of the Leica TS30. Once resections were completed, the stationing position of the Amberg trolley was locked in with the prism mounted on top of the Z+F 5006i laser scanner. Scan positions were re-established every 150 to 350 feet, depending on the location within the tunnel and other variables.
In areas where track had not yet been laid, especially around the 34th Street Station platform, at tangential crossovers and entrances to the tunnel shaft, the Amberg TMS positioning method was used. Resections were still needed to establish the position of the total station within the tunnel alignment, but instead of having the Z+F on a trolley, it was mounted onto a tripod and scan positions were re-established every 30 to 40 feet.