Museum of the American Railroad Update
June 22, 2012
Significant progress was made this week toward completion of track work. The four switches along the transitional trackage south of the Discovery Center are finished and ballast has been spread.
The process of “tamping up” the track began on Tuesday. This is the final stage of construction that brings the track into alignment at the proper design elevation. Tamping is achieved by raising the track up from the roadbed surface and working the ballast (crushed granite) in underneath the ties. A track based machine known as a ballast tamper can achieve the process at any point along the line in just a few minutes. Mechanized ballast tampers make short order of a process that was once slow and arduous, requiring several track workers.
Ballast tamping usually takes two to three passes with the machine in order to achieve final elevation and alignment. The first pass involves raising the track to final elevation at periodic staking points along the line. Each stake is placed according to survey points which indicate location and elevation of the track. Tamping between stakes then takes place to bring each segment up to elevation. Our design specifications call for five to six inches of the granite material to be worked in under the ties. Curved track will have a few degrees of “super elevation” where the outside rail is slightly higher than the inside rail. This “banking” of curves provides for easier movement of rolling stock and effectively lowers their center of gravity. The tamping process should be complete by the end of next week. A final process known as ballast regulation follows tamping. A track based machine removes excess ballast from the upper surfaces of the ties and spreads it to the outside of the track, creating a trim, manicured look to the right of way.
Meanwhile, BNSF track crews have completed construction of their switch which will connect the Museum’s lead track to the BNSF main line. Installation should take place next week, at which time work will begin on the Museum’s lead track. Upon completion of the lead track, the Museum will officially be connected with the general system and movement of the rolling stock collection will begin. This is tentatively scheduled to take place in mid-July. For updates on the Big Move, click here.