Mileposts 768 and 771 are within 1/4 mile of each other, just south of Sanford, between Airport Blvd and CR 46A. What realignments have caused this? The bypass of downtown Sanford just to the north only cuts off about a mile.

-- SPUI (drspui@gmail.com), November 01, 2004

Answers

I expect Aaron's answer is correct. If I get a chance to check the ACL branchline profile book, that might document the mileage difference conclusively. ACL established its milepost system as it took over the predecessor roads, in this case Plant System in 1902. ACL normally numbered its mileposts to correspond exactly to the predecessor's milepost locations, even where old changes resulted in "short" miles and so on.

As for a chaining book, the Society doesn't have one, but I assume there is one in the ICC collection at the National Archives and one that CSX still uses. I am not sure if we have a track map - the relatively few we have are not yet catalogued.

-- Larry Goolsby (lgoolsby@aphsa.org), November 04, 2004.

Never been there, but ACL's 1953 track chart shows that beginning at MP 765.7 (+ or -) and continuing to MP 770.9, it was laid in 100# rail rolled in 1928-29. The chart shows elevations and road crossings, but Mile Posts 768 and 769 have been blanked. It also indicates that Mile Post 2 equates to Mile Post 770.

-- Harry Bundy (Y6B@aol.com), November 04, 2004.

A possible source for the information you are seeking may be found in the Valuation Maps prepared by the ACL and filed with the ICC. These maps had the chaining equations along the original centerline as determined when the line was built, and any subsequent modifications. Most railroads also kept a "Chaining Book" where they entered the information on all realignments so that their engineers-especially those doing signal and bridge work, could accurately relate chainage to Mileposts. The chainage book would also reference the exact start of the chainage, any elevation equations, realignments, etc.

Does such a chainage book reside in any of the archives for either ACL or SAL?

As an example, the New York Central kept such a chainage book and this is used regularly here on Metro-North when we do signal design and bridge work. The elevation formulas are also vital-as information, the railroad's elevation 0 was a mark on the seawall adjacent to the old Bellevue Hospital on 26th street in Manhattan and is 2.71 feet above mean sea level as determined by the US C&G Survey!

-- Michael W. Savchak (Savchak@mnr.org), November 04, 2004.

SPUI, the old mainline that Joe mentioned in his response to you junctioned from the present-day mainline at a point under the SR 46 highway overpass on the north side of the Amtrak AutoTrain terminal, and extended on a southeast alignment to a point near S. French Ave (US 17/92), then extended southwest to a point on the present-day mainline near SR 46A. This distance is approximately 2 miles. If the distance included the additional track distance to the original ACL station in downtown Sanford (near the existing City Hall building), then the mileage would add up to 3 miles.

My guess is that the mileage distance included all of the above- identified trackage, which would account for the missing three miles.

-- Aaron Dowling (adowling@merandb.com), November 04, 2004.

That only adds about a mile though; where were the other 1.75 miles?

-- SPUI (drspui@gmail.com), November 03, 2004.

The old Aloma Branch (the track going by AutoTrain) used to be the mainline.It ran into downtown Sanford and reamerged somewhere near Airport Blvd.

-- Joseph Oates (uj67@mindspring.com), November 03, 2004.