Saturday, March 3, 2012

More plodding on Pittsburgh to Harrisburg Line

More examples of heavy freight operations.

This perspective is from the 24th Street bridge in Altoona over the Pittsburgh to Harrisburg line. The videographer is looking southwest upgrade. This is  milepost 237.3. The grade is 1.09 degrees. The passenger speed is 44 mph and the freight speed has changed from 25 mph to 35 mph ahead at milepost 237.5 where the signal bridge is seen. The opening scene shows an eastbound downgrade loaded coal train stopped. At the end of the video the coal train moves forward revealing the headlights of a helper engine in the distance seen through the signal bridge structure. The helper engine has been uncoupled. The purpose of a helper engine remaining on the rear of a heavy coal train downgrade from Gallitzin, top of the grade on the Allegheny frontal, is to provide additional regenerative braking. Heavy coal trains, of course, are controlled through the train's air brake system. Regenerative braking is done by a diesel electric locomotive  reversing the electrical current on downgrades. The electric motors driving the wheels are now acting as generators. Generators create resistance or braking energy. There is typically a higher pitched whining sound that comes from the locomotive when a locomotive is in regenerative braking. The heavy coal train has rounded the nearby Horseshoe curve at milepost 242.

As the loaded coal train on track 1 to the left is stopped, an empty coal train is seen moving upgrade on track 2 beneath the videographer. As that trains moves west, another westbound empty coal train is seen to the right on track 3. The westbound trains appear to be at or near 35 mph.

At milepost 237.3 all track capacity is being used. This is an example of a bottleneck that could be corrected by relaying the fourth track from Altoona to Cresson for passenger service. Note the space between track 1 and 2 in the video.

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This video is at the Horseshoe curve looking upgrade. This in the vicinity of Baker Run at about milepost 241.8 initially looking west. The curvature in the foreground is 9 degrees and tightens to 9.4 degrees in the center of the Horseshoe curve.  The grade is 1.34 degrees in the foreground and becomes steeper in the distance to 1.76 degrees. The freight speed is 30 mph and the passenger speed is 44 mph. The videographer has captured three freight trains. The first westbound freight trains appear to be moving at 30 mph. It is assisted with a helper engine pushing. The second train seen is a westbound intermodal train. Note that an intermodal freight train requires that the two helper engines used to move an intermodal train over the grade on the Allegheny frontal are at the head end to the intermodal train. The last train recorded is an eastbound, downgrade train. The helper engines attached are assisting with regenerative braking. The high pitched sound made by applying regenerative braking can be heard as they pass. All the trains' wheels make high pitched squealing and ringing sounds as they bind against the rail heads through the tight curvature. Both grade and curvature contribute to the horsepower required to move the freight trains shown. In order to control the downgrade freight train, it is operated at a speed well below 30 mph.

This video demonstrates the practical need to relay the fourth track from Altoona to Cresson if restored rail passenger service were not to interfere with freight operations as noted in the 2005 Woodside Consulting firm's study.

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The need to eliminate 1850's civil engineering design altogether by building a new line from Cresson to Tyrone is clear when watching these videos.

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