Southern Railway 4-8-2 Mountains (Class Ts / Ts-1): Specs & Roster

Published: August 27, 2026

The Southern Railway never rostered a 4-8-4. What it did roster, starting in 1917, was a two-class fleet of 4-8-2 Mountains to pull steel passenger cars that had outgrown the 4-6-2 Pacifics on the hills between Washington, Atlanta, Birmingham, and Chattanooga. Baldwin’s custom class Ts came first (30 engines, 1916–17). The United States Railroad Administration’s Light Mountain followed as class Ts-1 (25 engines, 1919)—the largest single USRA Light Mountain allocation of the 47 built nationwide. Southern’s letter T marked the 4-8-2; the trailing s meant superheated.

Together that is 55 Mountains on the Southern family: parent road, Cincinnati, New Orleans & Texas Pacific, and Alabama Great Southern. They took Virginia green and gold in the late 1920s, the same passenger dress as the famous Ps-4 Pacifics. None were saved. The last came off in 1952–53. Southern’s steam celebrities that remain—Ps-4 1401 at the Smithsonian, Mikado 4501 at TVRM—are other wheel arrangements.

Southern Railway 4-8-2 1459 at Asheville, NC In 1950

Southern 4-8-2 #1459 (Class Ts) awaits the arrival of train #28 at Asheville, North Carolina on February 16, 1950. The Mountain would lead the train eastbound into Charleston, South Carolina. From the Shelby Lowe collection.

On this page: At a glance · Why a Mountain · Class Ts · Class Ts-1 (USRA) · Specifications · Complete roster · Green and gold · Service and retirement

At a Glance

Item	Detail
Railroad	Southern Railway System (parent, CNO&TP, Alabama Great Southern)
Wheel arrangement	4-8-2 Mountain (Whyte); 2′D1′ UIC
Classes	Ts (Baldwin custom, 1916–17); Ts-1 (USRA Light Mountain, 1919)
Quantity	30 Ts + 25 Ts-1 = 55
Why the 4-8-2	Steel passenger cars on grades that 4-6-2 Pacifics could no longer time
Drivers / pressure (both classes)	69-inch drivers, 200 psi
Ts vs Ts-1 cylinders	Ts 27×28 in; Ts-1 27×30 in (USRA Light)
Tractive effort	Ts ~50,300 lbf; Ts-1 ~53,900 lbf
Paint (from late 1920s)	Virginia green and gold, same family as the Ps-4s
Retired	1952–53. No survivors

Why Southern bought Mountains

The 4-8-2 was born on the Chesapeake & Ohio in 1911, when Alco stretched a Pacific into eight drivers for the Alleghenies and C&O named the type Mountain. Southern’s problem was the same geometry on different hills. Between Washington and Atlanta, and on the Birmingham, Bristol–Memphis, and Macon–Chattanooga runs, all-steel coaches and sleepers made the older Pacifics late. A two-axle engine truck, four coupled axles, and a trailing axle under a wide firebox gave more adhesion and more boiler than a 4-6-2 without jumping to a 2-8-2 freight engine’s smaller drivers.

Southern did not wait for the USRA. It ordered a custom Baldwin Mountain in 1916, classed Ts, and put 23 on the parent road as 1450–1472 plus seven more on the Queen & Crescent subsidiaries. When the United States Railroad Administration standardized a Light Mountain in 1918, Southern took the biggest slice of that 47-locomotive pie and classed the copies Ts-1.

The later Ps-4 Pacifics (Alco, 1923–26) stole the Crescent and the Washington–Atlanta varnish that photographers remember. The Mountains kept working: passenger extras, mail and express, and fast freight on the same districts, often based at Spencer, North Carolina, and working both directions on the Washington–Atlanta main.

Class Ts — Baldwin, 1916–17

Thirty locomotives. All Baldwin. Works numbers run from 44666–44667 (December 1916) through 46062 (August 1917). They are not USRA engines. Cylinders are nearly square, 27 by 28 inches, fed by 14-inch piston valves. Walschaert valve gear. 69-inch drivers, 200 psi, about 50,290 lbf starting tractive effort. Engine weight 314,800 pounds; 209,800 on drivers.

Road numbers:

Southern 1450–1472 (23)—the parent-road series everyone photographs
CNO&TP 6490–6494 (5)—built as 850–854, later 6490-series
AGS 6695–6696 (2)—built as 280–281, then 6690–6691, then 6695–6696

Tenders as diagrammed carried about 9,000 gallons of water and 12 tons of coal (171,000 pounds loaded). Grate area 77 square feet—larger than the USRA Light Mountain that followed. Firebox heating surface about 329 square feet including arch tubes as built (a 1926 diagram is too low to still include those tubes, so some may have come out in shopping).

Class Ts-1 — USRA Light Mountain, 1919

The USRA Light Mountain (4-8-2A) was the wartime standard dual-service 4-8-2: 69-inch drivers, 27 by 30 cylinders, 200 psi, about 53,900 lbf tractive effort, 327,000-pound engine, Baker valve gear on the USRA drawing (Southern diagrams should be checked per unit if a Ts-1 was later given Walschaert). Forty-seven originals were built for four railroads. Southern’s family took 25.

As delivered they were Southern 1475–1499: Baldwin 1475–1489 (15), Alco-Richmond 1490–1499 (10). Five of the allocation went to CNO&TP as 6495–6499 (Alco-Richmond 6495–6498, Baldwin 6499). Three Baldwin engines associated with 1484 / 1488–1489 went to AGS as 6692–6694. Published tables that add 1475–1499 plus 6495–6499 plus 6692–6694 into 33 new locomotives are counting the same 25 twice. USRA math is 7 Missouri Pacific + 5 NC&StL + 10 New Haven + 25 Southern family = 47.

Ts-1 tenders were larger than the Ts: about 10,000 gallons and 16 tons of coal. The USRA boiler used a combustion chamber; evaporative heating surface about 4,121 square feet, superheater about 966, grate about 70.3 square feet. That is more boiler, slightly less grate, and a longer stroke than the 1917 Baldwins.

Specifications

Figures follow Southern diagrams as compiled by Steve Llanso (Locobase 227 / 1429), the 1930 Locomotive Cyclopedia USRA Light Mountain sheet, and Richard E. Prince’s Southern steam roster. Tractive effort is the usual 0.85×P×d²×s / D calculation at 200 psi.

Specification	Class Ts (1917 Baldwin)	Class Ts-1 (USRA Light, 1919)
Whyte	4-8-2	4-8-2
Builder	Baldwin	Baldwin and Alco-Richmond
Cylinders (2)	27 × 28 in	27 × 30 in
Drivers	69 in	69 in
Boiler pressure	200 psi	200 psi
Starting tractive effort	50,290 lbf	53,900 lbf
Valve gear	Walschaert; 14-in piston valves	USRA standard Baker (confirm a given engine against its diagram)
Engine weight	314,800 lb	327,000 lb
Weight on drivers	209,800 lb	224,500 lb
Max axle load	54,900 lb	56,500 lb
Tender (loaded)	171,000 lb	192,000 lb
Engine + tender	485,800 lb	519,000 lb
Tender water	9,000 gal	10,000 gal
Tender coal	12 tons	16 tons
Driver wheelbase	18 ft 0 in	18 ft 3 in
Engine wheelbase	38 ft 11 in	40 ft 0 in
Engine + tender wheelbase	73 ft 3½ in	75 ft 8½ in
Grate area	77 sq ft	70.3 sq ft
Firebox heating surface	329 sq ft (as built, with arch tubes)	348 sq ft (includes combustion chamber / arch tubes)
Evaporative heating surface	3,668 sq ft	4,121 sq ft
Superheater	942 sq ft	966 sq ft
Combined heating surface	4,610 sq ft	5,087 sq ft
Factor of adhesion	~4.17	~4.17

Complete roster

Road-number blocks, not a builder-card dump. Baldwin works numbers for the Ts are in Prince and in DeGolyer Volume 56; they run 44666 (December 1916) through 46062 (August 1917). Ts-1 Baldwin works include 51647, 51653–51654, 51704–51705, 51730–51733 (April 1919) and 51798–51800, 51814, 51865 (May). Alco-Richmond Ts-1 works include 59800-series numbers for the 1490s and CNO&TP 6495–6498.

Class Ts (30)

Road	Numbers	Qty	Builder	Year	Notes
Southern	1450–1472	23	Baldwin	1917 (first two Dec. 1916)	Parent-road passenger Mountains. All scrapped
CNO&TP	6490–6494	5	Baldwin	1917	Built as 850–854; Queen & Crescent / Cincinnati–Chattanooga. All scrapped
Alabama Great Southern	6695–6696	2	Baldwin	1917	Built as 280–281, then 6690–6691, then 6695–6696. All scrapped

Class Ts-1, USRA Light Mountain (25)

Road	Numbers	Qty	Builder	Year	Notes
Southern	1475–1489	15	Baldwin	1919	USRA Light Mountain. Three of this Baldwin group associated with AGS 6692–6694 (ex 1484, 1488, 1489 in some lists)
Southern	1490–1499	10	Alco-Richmond	1919	USRA Light Mountain
CNO&TP	6495–6498	4	Alco-Richmond	1919	Part of the Southern family’s 25, not a 26th through 29th new engine
CNO&TP	6499	1	Baldwin	1919	Same allocation
Alabama Great Southern	6692–6694	3	Baldwin	1919	Same allocation. Do not add these three to 1475–1499 as extra new locomotives

Parent-road photographers will see 1450-series Ts and 1475-series Ts-1. Subsidiary engines wear 64xx (CNO&TP) and 66xx (AGS). There is no 1473, 1474, or 1500 in the Mountain series. There is no Southern 4-8-4 behind them.

Virginia green and gold

Fairfax Harrison, Southern’s president, had the Ps-4 Pacifics painted Virginia green and gold after seeing LNER apple green in Britain (the first Ps-4s had been black with gold lettering). In the late 1920s that passenger livery went onto the Ts and Ts-1 as well. They kept it until dieselization. If a color photograph of a Southern 4-8-2 looks like a Ps-4 with two extra drivers, that is the point. Freight Ms-class Mikados stayed black.

Where they ran, and why none survive

The Washington–Atlanta main through Spencer is the assignment every summary repeats, both directions, steel cars. They also covered Atlanta–Birmingham, Bristol–Memphis, and Macon–Chattanooga—the hills that had finished the light Pacifics. After the Ps-4s took the flagship varnish, Mountains remained useful dual-service power: passenger when a Pacific was short, mail and express, and timed freight. CNO&TP engines worked the Cincinnati gateway; AGS engines the Birmingham–Meridian side of the Queen & Crescent.

Southern dieselized passenger trains relatively early by Southeastern standards. The Mountains came off in 1952–53. Every Ts and Ts-1 was cut up. No museum, no park engine, no Southern steam program 4-8-2. The system saved a Pacific and later a Mikado. It did not save a Mountain.

That is the whole fleet: thirty Baldwin customs and twenty-five USRA Lights, 69-inch drivers, green and gold on the varnish, gone with the rest of Southern steam. If a surviving 4-8-2 in the South is on your itinerary, it is not one of these.

Sources

Richard E. Prince, Southern Railway System Steam Locomotives and Boats (1970)—standard all-time Southern steam roster
Steve Llanso / SteamLocomotive.com Locobase 227 (Ts) and 1429 (Ts-1), from Southern diagrams, DeGolyer Vol. 56, and the 1930 Locomotive Cyclopedia
USRA Light Mountain allocations (47 originals: MP 7, NC&StL 5, New Haven 10, Southern family 25)
Baldwin DeGolyer specification books, Vol. 56 (Ts) and Vol. 58 (USRA Light Mountain)
HawkinsRails Southern steam notes (1450–1472 / 1475–1499; retirement by 1953; no survivors)