REM utilizes "launching gantries" to construct light-rail elevated structure

June 20, 2019
Two of the behemoth machines will work in tandem over the next three years to assemble the prefabricated segments.

Réseau express métropolitain (REM) is employing an unusual method to construct the 14.5 km (approximately 9 miles) of elevated structure for future light-rail trains to travel over in Greater Montreal. Two launching gantries – enormous yellow machines – are assembling the prefabricated sections of the structure piece-by-piece. 

The machines are 105 meters (344.48 feet) long and can support 550 tons, which will come in handy as each concrete segment weighs between 42.3 and 57.7 tons. REM explains the beams raise the prefabricated segments and slide them up against one another to form the deck on when the REM’s rail cars will run. 

"That’s why they're called 'launching gantries' – because the prefabricated segments are 'launched' one after the other," said REM.

There are several advantages REM lists to utilizing launching gantries such as limiting the amount of work performed at heights, the quality of the structure built is increased due to prefabrication, there is a decreased impact on road traffic, the repetitive process requires minimal workers and equipment and the construction speed is increased with this method.

"It’s quite an impressive construction method and ensures things to move forward very quickly. On average, it takes two days to erect one span, that is, to cover the distance between two columns (30 to 40 metres)," explained REM. "Once the span is complete, the beam is moved forward to the next two columns, and the process is repeated. It will take [the two gantries] three years to build the entire 14.5-km section of elevated structure."

The two launching gantries have been named Marie and Anne. The first launching gantry, Marie after Marie Curie Street in the Technoparc, will assemble the elevated structure between the Technoparc and the midway point, Fairview Pointe-Claire. From that midway point, the second launching gantry, Anne, will build the remaining section of elevated structure, up to Sainte-Anne-de-Bellevue, which is where the machine gets its nickname.

About the Author

Mischa Wanek-Libman | Editor in Chief

Mischa Wanek-Libman serves as editor in chief of Mass Transit magazine. She is responsible for developing and maintaining the magazine’s editorial direction and is based in the western suburbs of Chicago.

Wanek-Libman has spent more than 20 years covering transportation issues including construction projects and engineering challenges for various commuter railroads and transit agencies. She has been recognized for editorial excellence through her individual work, as well as for collaborative content. 

She is an active member of the American Public Transportation Association's Marketing and Communications Committee and serves as a Board Observer on the National Railroad Construction and Maintenance Association (NRC) Board of Directors.  

She is a graduate of Drake University, where she earned a Bachelor of Arts degree in Journalism and Mass Communication with a major in magazine journalism and a minor in business management.