> I guess the Histerical Society knows more
> than the people that run the train at Cass,
> as they advised us on the train, on a trip
> that I took many years ago, that the grade
> was 14% just below Bald Knob. In any
> event...it's steep!

The current "Bald Knob Approach" is 9%. Up until (IIRC) the very early 1970's it used to jog a bit to the left and was steeper. I think something like 11%. Maybe even the 14% that was mentioned. The steepness and the curvature used to limit the length of the Bald Knob trains, so it was straightened into the present alignment. During the Mower logging days, the track actually went much farther to the left and circled the ridge in the opposite direction to reach the landing at the summit.

The track coming out of the second switchback and around the S curves below Whittaker has long been mis-labelled as being 11%. Some years back someone actually took instrument readings and found this section to be at 8.7%. The reverse curves and steepness make this a hard pull (well actually a hard push!). An even greater challenge is the start from the Oats Run water stop. A REALLY tight left hand curve combined with another stretch of 8%. Not uncommon to hear even a shay slip at this spot!

Regards,
Jim Robinson

Many thanks to all of you for such great help! Didn't realize I'd be starting such a long thread, but glad it has so much good discussion. Maybe my question wasn't so dumb after all. Thanks for all the encouragement.

William

> The current "Bald Knob Approach"
> is 9%. Up until (IIRC) the very early 1970's
> it used to jog a bit to the left and was
> steeper. I think something like 11%. Maybe
> even the 14% that was mentioned.

My trip was in the late 1960's, so it must have been on the old approach. Thanks for your input!

dougnleffler@yahoo.com

> I want to compare the
> steepest grade on the San Francisco cable
> car system (21%) with a more familiar
> situation for the audience.

According to George Hilton's "The Cable Car in America" the steepest grade in the US was 27.7% of the Second Street Cable Railway in Los Angeles! The steepest in the world was a 28.5% in Dunedin New Zealand.

I have seen some plans for contemporary residential streets up hillsides that are 20%+.

Brian Norden

> According to George Hilton's "The Cable
> Car in America" the steepest grade in
> the US was 27.7% of the Second Street Cable
> Railway in Los Angeles! The steepest in the
> world was a 28.5% in Dunedin New Zealand.

> I have seen some plans for contemporary
> residential streets up hillsides that are
> 20%+.

As a practical example of what a grade can do, C&IM's 2-mile long Petersburg Hill in central Illinois varied from .94 to 1.64% and required a 2-10-2 pulling 6,000 tons to triple the hill. Even the multiple-unit diesel usurpers had to double the hill.
> Brian Norden


justighe@bright.net

Even I'm not crazy enough to take passengers down a 15% grade! Our maximum posted grade is 8.48% just below Grizzly Flats. The switch back is probably between 8 and 9 but no one has ever measured it. The steepest grade I ever heard of was an 18% grade on the Eagle Gorge Railroad in Washington State. They lost a Heisler on the hill and the parts are still down in the gorge.

Tom Shreve
Senior Engineer
Roaring Camp & Big Trees

ironbartom@aol.com

> What might be the maximum grade allowable

David Jehan in the introduction chapter to'Rack Railways of Australia'[and he's a mechanical engineers working in the industry] states;

'locomotives propelling trains are limited to a gradient of approximately 1 in 14 (7.1%) or less. Beyond this figure there is a risk that the locomotive driving wheels will slip whilst ascending the grade, or more importantly, it may slide out of control during a descent. Single vehicles with all wheels driven, such as trams (streetcars to you guys-GB)are slightly different, as all of the mass of the vehicle is actually providing adhesive wight for the driving wheels. Thus the limiting gradient... is much higher, being approximately 1 on 9 (11.1%) although gradients of 1 in 7.4 (13.5%)... have been recorded.'

The Fell centre rail system (patented in 1866)uses a centre rail friction drive was developed for the Mount Cenis Pass railway between France and Italy that opened in 1868 & was replaced by a tunnel in 1871. However, the best known example of this system was the Rimutaka incline in New Zealand (1878-1955)that was 3 miles long and had a ruling grade of 1 in 14 (7.1%).

The Mt Washington railway (1869), using the Marsh rack system has a ruling grade of 1 in 2.67 (37.4%).

The standard gauge Rigi railway (1871) using the Riggenbach rack system runs from the shore of Lake Lucerne Switzerland. Of the 4.3 miles of route about 1 mile rose at 1 in 4 (25%) and the remainder mostly at 1 in 5 (20%).

Jehan goes on state that Dr Roman Abt [1850-1933, the swiss engineer who invented the most widely used rack sysyem in the world]publicly professed that, to be safe, no mountain railway should attempt a grade of more than 1 in 4 (25%). The firt Abt line (Harzbahn in Germany) had a 1 in 17 (5.9%)grade.

Experiments confirmed that on a grade of 1 in 2 the least discrepency in the pitch of the rack teeth (such as is unavoidable through wear) caused the driving pinion to override. That caused Cornel Edward Locher to invent a system with a horizontal rack. The only application of the Locher system is on the Swiss Piltus-bahn an 800mm gauge line, 4.5 km long (circa 7miles) with a ruling grade of 1 in 2.1 (47.6%). The coaches have stepped floors and the top speed is 9km.h

Strub's rack system has been applied on the 9km (circa 14 mile) Jungfrau-bahn in Switzereland with a ruling grade of 1 in 4 (25%) and on lines in Italy and Germany.



Puffing Billy Steam Railway, Australia
chairman@pbr.org.au

Thanks very much for the good information! Interesting that Abt said not to exceed a 25% grade. That's exactly the steepest grade on the Pike's Peak Cog Railway in Colorado, which uses the Abt rack system and has been operating since 1891 without a single significant accident.

> Interesting that Abt said not to exceed a
> 25% grade. That's exactly the steepest grade
> on the Pike's Peak Cog Railway in Colorado,
> which uses the Abt rack system and has been
> operating since 1891 without a single
> significant accident.

I'd love to see it. We have a recently rebuilt Abt steam tourist railway here in Australia (link below), but the max grade is 'only' 1 in 20 (5%).


West Coast Wilderness Railway
chairman@pbr.org.au