Abo Canyon Second Main Track

Transcription

1 Abo Canyon Second Main Track Thomas Schmidt Director Engineering Services BNSF Railway David Miller Manager Engineering BNSF Railway

2 Abo Canyon Second Main Track Building 5 miles of a second track through a canyon and along an existing single track with up to 80 trains per day.

3 Original Construction The Belen cut-off was built to provide the Santa Fe with an alternative to its original route through Colorado and northern New Mexico, which has grades of over 3%. To get through a near vertical drop of 500 feet at the Manzano Mountains, a route following Abo Arroyo was chosen.

4 The Need for Double Track With most of the route double tracked in the 1990s and with increasing train traffic on the Transcon, the single track at Abo Canyon became a serious bottleneck in the line.

5 Many artifacts from the original construction of the line and the early settlement of the area were located in or near the canyon. Environment and History Not affected by the construction, but within the canyon is rock art dating to , which was identified and protected.

6 A 404 permit was required from the Army Corps for the 0.11 acres of temporary fills in the channel. The temporary fills were for the improved access roads and crane pads necessary for bridge construction. Permitting and Wildlife No endangered species were located in the construction area, However, a flock of Bighorn Sheep lives in the canyon. As part of the project, BNSF constructed game fence to keep the sheep and other wildlife off the tracks.

7 Route Selection After several alternate alignments were considered for the second track, a 40 mph alignment that was mostly on the south side of the existing track was chosen. The route chosen avoided impacts to an existing landslide and had fewer impacts to cultural resources than the other alternatives.

8 Although most of the new track was on the south side of the existing track, in several places it had to swap sides due to high steep hillsides or due to the location of cultural resources. Design Most cuts were designed so that blasting and grading work was not next to the live track

9 Grading and Blasting About 1.8 million cubic yards of excavation. About 1 million cubic yards of embankment. Daily planning and coordination was required to be able to excavate and haul rock while having a place to make a blast and another place to drill holes for the next days blast.

10 Blasting Nearly all excavation was rock that had to be blasted. Each workday a minute window was arranged with the train dispatcher to make a blast. 520 explosion shots 1,681,465 pounds of explosives. Up to 13,000 cubic yards of rock per blast.

11 Blasting In a few locations, large cracks and loose rocks near and above the live track made it likely that a rock might fall on the track. In those areas, extra track time was scheduled, blast mats were placed on the track, and equipment was positioned ready to clean up after the blasts.

12 Grading After the rock was broken by the blasting, it was excavated and moved to embankment or stockpile locations. When the grade was completed, 9 inches of subballast was placed. The subballast was crushed using suitable rock from on site.

13 Bridges Of nine bridges built on the project, seven were large bridges crossing the creek as it winds through the canyon. Over 3000 feet total length of bridges. The largest bridge is 600 feet long and 80 feet high.

14 Bridges Bridge foundations used CIDH piles. 6 foot diameter holes were drilled down until competent rock was reached, then a 5 foot diameter rock socket was drilled at least 10 feet into the rock. Above the rock, the drilled holes were cased with steel pipe. Rebar cages were tied on site for the shafts, grade beams, columns, and caps.

15 Bridges Each pier had two 6 foot columns. The new bridges were designed to complement the existing bridges so that the flow characteristics of the arroyo are unchanged No permanent fill was placed within the 100-year high-water elevation of the Abo Arroyo in the canyon.

16 The longest spans used 102 foot long steel plate girders with steel deck and walkways. Bridges Access roads through the canyon and crane pads at each bridge had to be built.

17 Bridges Several spans used 80 foot precast concrete I-beams where they fit with the desired span lengths. These spans had cast in place decks.

18 Track and Signal The previous end of single track at the west end of the canyon had crossovers added to connect the new track and to have a permanent universal crossover location. All access to the new track during construction for work trains and on track equipment was through the connection at the west end.

19 Track and Signal Each switch installation, track lineover, and signal cutover was scheduled to start early on a Tuesday morning. Due to having the lightest train traffic of the week, Tuesday mornings have been the time for scheduled maintenance on the single track for many years.

20 Track Due to working up a 1.25% grade, a second tractor was used to help pull the TLM BNSF s track laying machine was used to build the new track. Welded rail was laid out in advance and a work train brought new ties to the TLM in the evenings.

21 When the new track was completed up to each of the four locations where it changed to the other side of the existing track, a lineover had to be done. Track Six hours were usually available before the track had to be open for train operations.

22 Track In order to be complete, the new track had to be destressed. Surfacing and ballast dressing also had to be completed, signs had to be up and general cleanup done.

23 Although at most locations the construction work was not next to the line track, there was one location where it was very close due to the narrow canyon and the high hillsides. Sliver Cut The existing track had to be moved away from the toe of the hillside before the cut could be completed next to the track.

24 Rockery Wall A stacked rock wall using relatively flat rocks selected from the excavation material was built in an area where fill slopes could not be placed without being within the creek. In addition to having a lower cost than a typical retaining wall, the rockery wall s appearance fits in better with the canyon.

25 Ercon Jetties Ercon Jetties were placed in front of the rockery wall and at another location where there was the possibility of the creek moving toward the embankment that the track was on. By slowing the flowing water, they reduce the risk of erosion.

26 Game Fence Over 6 miles of game fence was constructed to keep the Bighorn Sheep and other wildlife off the tracks. The animals are able to get from one side to the other under each of the bridges. In case an animal gets on the wrong side of the fence, there are several escape ramps so they can get out by climbing the ramp and jumping down.

27 Double Track With the second main track in service, trains that once waited up to three hours for a slot to pass through Abo Canyon can now go without waiting. With Abo Canyon complete, BNSF now has only 32 miles of single track remaining on the Chicago to Los Angeles Transcon route.

28 Double Track