Tuesday, January 6, 2015

Mile 132 Copper River Trestle

According to the 1913 Alaska Railroad Commission report,
While not a part of the proposed main line from Cordova to Fairbanks, as a freight tributary this branch will form a most important factor in the success of the through line, and therefore merits a brief description. The Kennicott Branch of the Copper River & Northwestern Railway produces virtually the only tonnage now hauled by that road. The branch extends from Chitina about 64 miles eastwardly to Kennicott, where is located the famous Bonanza mine.

From Chitina the road passes through a short tunnel coming out upon the west side hill of the Copper River, and crosses that river just above the mouth of the Chitina. This crossing, as built, is feasible for the traffic accommodated, but is of a temporary character and not as originally designed. It is about 70 feet below the location level and necessitates a climb on a 3 per cent grade to the north bank of the Chitina. . . .

The 1915 Alaska Engineering Commission report expands on this:

The crossing of the Copper River at mile 132, near Chitina, is made on a temporary pile trestle bridge at a low level, with the approaches on 4 per cent grades. A permanent steel bridge at this point would cost about $650,000, and the railroad company considers that it results in economy to replace those portions of the temporary bridge swept away by the spring floods each year rather than pay interest on this heavy investment. The traffic is thus interrupted for about two weeks while the trestle is being redriven.

Here is a very distant view of the Bridge 132 trestle from the north. Chitina and the tunnel are to the right.

Here is an overall view from farther to the northeast:

Here is a more close up view showing the roller-coaster actuality of this "temporary" bridge, looking from the line toward Kennicott:

Here is a view looking back at the photo angle above:

Here is a view from the Chitina side of the Copper River:

The 3%-4% grades in the approaches described in the reports are easy to see in the photos above. As the reports described, washouts of this bridge were routine, probably an annual occurrence with each spring's ice breakup:

Here is a shot of what appears to be the repeated reconstuction of the bridge:

After 1932, the railroad ceased operation during the winter, and stringers and rails were removed from the bridge in the fall, to be replaced after breakup in the spring. Here is a shot of this process:

Nevertheless, the bridge still regularly washed out. Here is a shot of a washout on August 17, 1932:

At some point after 1932, a cable tram was built parallel to the railroad trestle, presumably to provide access across the river when the bridge was washed out and the railroad was not operating. The cables at upper right are part of this tram:

The pile drivers show the continuing railroad maintenance needed even at this late date. It's possible that the pile driver at center was there permanently and skidded into place when needed.

Here is a rider on the cable tram:

A later view of the cable tram:

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