PRR 5550 Update: Boiler Assembly

Alexander D. Mitchell IV · **Posted:** Mon Oct 31, 2022 5:30 pm

jayrod wrote:

It’s not surprising at all that mile posts are off. Once established, the markers, if they still exist, don’t seem to be moved after a line has been re-surveyed due to changes. Their actual positions are usually noted on the charts in stations which are pretty accurate.

I took on a project to research and redraw an up to date track chart to scale for a tourist line. Quite a few of the MP locations weren’t exactly a mile apart though not terribly off. However, to complicate things, I can only assume that the last survey was done from both ends on one division which left a gap of almost a quarter mile on the old chart meaning those two adjacent MP locations were only about 3/4 of a mile apart. The error in placing the MPs was never fixed so for continuity the gap remains on the new chart notated to represent the original error so the MP locations are easier to find.

In Britain, where measuring locomotive performance via timing by stopwatch became its own obsessive-compulsive subset of "trainspotting," one used to be able to purchase booklets that would give you the ACTUAL confirmed distances between "official" mileposts on British Railways. "Official" timings by such noted practitioners as O.S. Nock, P.W.B. Semmens, Cecil J. Allen, and others were checked against such lists before publication in magazines such as Railway Magazine and Railway World.

https://archive.org/details/in.ernet.dl ... 3/mode/2up

A quick check online shows that the publisher, or at least an heir to the company, is still publishing said books:

https://www.facebook.com/RailwayDistances/

co614 · **Posted:** Mon Oct 31, 2022 7:27 pm

With the availability of all the modern technology at our disposal today ( satellite tracking, gps, speed measuring devices accurate to the tiniest fraction of a mile per hour) securing accurate measurements of her achieved speeds will be the easiest part of the enterprise.

IMHO-Ross Rowland

superheater · **Joined:** Sun Aug 22, 2004 11:54 pm **Posts:** 2605

Before you get all excited by the idea that GPS is inerrant, keep in mind that Steamtown was relying on GPS to provide continual observance of the Pocono Main speed limit at one time. It's reliability became suspect when it reported one excursion train was reported to be doing something like 130 miles per hour. It was surmised that lush Pocono extending over the tracks in parts of the line East of the Summit was interfering with signal continuity and so the unit was "interpolating".

If terrestrial electronics can detect wheel slip, surely you can use electronic wheel speed measurements, lasers or radar to provide a measurement +/- .1mph....

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

Differential GPS with ground beacons would easily give any resolution needed to confirm a record speed. Presumably the receiver would either be held at constant temperature or given an enclosure with an oven to eliminate the irritating problems iPhones and similar devices have with uncompensated drift.

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

superheater, since you have PMs disabled, did you get all the explanation you wanted, in the plain English you desired?

Andy Nold · **Joined:** Tue Dec 14, 2004 5:45 pm **Posts:** 297

I'm sure there are plenty of qualified surveyors with the equipment necessary to certify a speed record regardless of the spacing between mile markers. When I worked in Dallas, my company certified a longest something or other for Guinness in the parking lot of the basketball arena.

Regards,

Andy N., RPLS

superheater · **Joined:** Sun Aug 22, 2004 11:54 pm **Posts:** 2605

Overmod wrote:

superheater, since you have PMs disabled, did you get all the explanation you wanted, in the plain English you desired?

Yes, thanks. Also thanks for alerting me about PM's were disabled; but I think I understand the basics now, as much as I can-given that I'm not headed back to college for an engineering or physics degree.

hullmat991 · **Joined:** Sun Dec 28, 2014 11:12 pm **Posts:** 231

Didn't quite feel sure if this deserved a new thread; but the T1 Trust sent out an email today with an update on where they're at with the frame.

https://prrt1steamlocomotivetrust.org/frame-club/

PMC · **Joined:** Sat Oct 17, 2015 5:55 pm **Posts:** 2874

hullmat991 wrote:

Didn't quite feel sure if this deserved a new thread; but the T1 Trust sent out an email today with an update on where they're at with the frame.

https://prrt1steamlocomotivetrust.org/frame-club/

Did I read this right, that they initially believed that the frame would cost $900K to construct, but that they received a quote of $350K? I would bet that can't be, because there are two separate price components, the metal pours and the fabrication. But if so that is a phenomenal break, especially these days, when one would expect prices to be going the other way around.

BWills · **Joined:** Thu Feb 02, 2023 1:55 pm **Posts:** 80

ya I will say their website leaves a little to be desired in terms of easy to find progress/ updates/ costs etc.
For example I don't see a total projected boiler cost, maybe it's buried within a video or something.
Then they don't really say what's all included in the "frame" does this mean just the main frame, or also rear cradle, or also including the integrated cylinder "blocks". no idea.
But 350K is great news!
Makes you wonder if the frame for something like a NYC hudson would be more like 200-250k.

Overmod · **Joined:** Thu May 24, 2012 1:37 pm **Posts:** 2492

The likely chosen construction would be hydroformed sections, joined to lost-foam castings for the 'critical' pieces. I advocated laser keyhole welding in CA for the required relatively deep full-pen sections; we shall see.

The quotes for full-casting a replica engine bed (in historic CSC style) were never less than $1M... with no guarantee that the first, or the second, or any actual casts at that price would be serviceable.