Session Seven: Blaster’s Spotlight: Demolition of the Milwaukee Railroad Trestle Pier
(Room Lone Star DEF)
27 Jan 18
3:20 PM
-
4:10 PM
Tracks:
Blasters Training Seminar
Demolition blasting next to an active railroad can be very challenging because of track safety, maintaining blasting vibrations ≤ 4 in/sec, potential track fouling by blast debris, and short work windows on a live track. In eastern Washington, the railroad constructed a second main track to accommodate the expected increase in rail traffic. Blasting demolition techniques were employed to remove an old railroad trestle pier on the Milwaukee Road that was in the footprint of the new track bed. The trestle bridged the present rail line and flanked the track with two massive 550-ton (499 tonne) twin-columned steel reinforced concrete piers. The blast was designed to open the backside of the pier using a delayed V-notch cut to insure both columns of the trestle pier fell away and did not foul the active track. On March 15, 2014, the south columns were successfully blasted using a V-notch blast design and approximately 24 pounds (11 kg) of dynamite per column. The blast was designed to shoot a maximum of about 9 pounds (4 kg) of dynamite per delay with a 17-millisecond delay between detonation of the first and second columns. The pier fell cleanly as designed away from the track.