Confronted with the device pictured here, the casual observer might conclude Southern has taken to carting its own portable tunnels around.
Actually, it's a portable form being used for the pouring of the concrete lining inside the greatly enlarged Swannanoa tunnel on Southern's Asheville division. "Opening up" the Swannanoa is part of the railway's bottleneck-breaking project on the Asheville division, where seven narrow tunnels with low clearances have in the past kept Southern's big new cars from being used most effectively to save money for shippers and the public.
In the past, such equipment as the "Big Boy" box cars and others have had to be circuitously routed to avoid these low, narrow clearances on the division. Work being done on the Asheville division will let our largest cars travel by the most direct routes to serve our customers better. Result: Savings in time and money for all concerned.
It was also in the interest of saving time and money that the contractor on this job, Cowin & Company, Inc., of Birmingham, Ala. conceived of the form shown here at the Swannanoa tunnel.
The form "slips" inside the permanent steel frame ( seen projecting from the end of the tunnel) which lies against the natural face of the greatly enlarged bore of the Swannanoa tunnel. When the form is in place, 17 inches of space remains between it and the permanent steel frame.
The outside of the form fits snugly at the bottom against a permanent concrete "curb" that is poured beforehand. This curb is as high as track level, which is two feet higher than the lip of the form.
Once the 30-foot-long form is in place, concrete is pumped through the "doors" which can be detected in vague outline on the form top and sides. One door near the top in the side of the form is open, as are two doors in the top of the form.
The concrete while filling the 17 inch space between the form and the steel frame that lies hard against the natural wall of the tunnel is kept from running out the sides by wooden sheeting which is held in place at the bottom by the curb.
When the concrete has set, the form is "broken loose" through the operation of mechanical devices which swing the bottom of the form inward, causing the form to slip down and away from the hardened concrete. Then the form is moved on to the next 30-foot section that is to be poured.
This form is being used in the Swannanoa tunnel only. In other tunnels being "opened up," wooden forms are being used because the curvature of the track inside the tunnels makes it necessary to construct each section of form according to local conditions.
The expense of using wooden forms inside the 1,822-foot-long Swannanoa is being avoided through the use of this steel form; and the time-saving use of the steel form is made possible by the straight line of the track going through Swannanoa tunnel.
So the actual work of "opening up" the Swannanoa is being carried out in the same spirit as that which led to the project in the first place -the spirit of doing the job at hand in new ways that will save time and money for everyone concerned. .