The era that I am modeling covers the period when the Highland Line transitioned from full steam power to full dieselization, and then to replacing passenger trains with Budd RDC trains.

Steam Locomotives

The New Haven Railroad rostered nearly a thousand steam locomotives from 1900-1950. As there is far too much information for me to provide here, see Ed Ozog's great site NYNH&H Steam Locomotives from A to Z as well as Jack Swanberg's book New Haven Power for more details.
 
Steam locomotives are listed by the New Haven Railroad class as opposed to the popular naming conventions. For example, I-series locomotives (I-1, I-2, I-3 and I-4) were all 4-6-2 pacifics.
 
Last Steam from Waterbury
Former New Haven fireman Noel Weaver reported the last of each steam class used in Waterbury on the NHRHTA Forum.
  • I-1 #1001 to Boston with a snow plow and a derrick on May 17.
  • F-5 #164 on a work train on Aug 20.
  • I-2 #1331 on 136 to Boston on Nov 20.
  • K-1-b #388 on a work train on Dec 15.
  • J-1 #3003 on a work train on Dec 23.
The work trains were out of Waterbury, but there's no record of whether any of them visiting New Britain. The locomotives listed were the last of their class, so other road numbers may have been used prior to these dates. But the only revenue train still using steam in 1948 was 131-136, and that was becase motive power was assigned in Boston.

Diesel Locomotives

The New Haven Railroad was quick to see the tremendous cost savings that would result by replacing steam locomotives with diesel-electric locomotives. As early as the late 1930's they were already replacing switchers are their major terminals with early Alco HH-600 and HH-660 locomotives. This started what I see as the first phase of New Haven diselization to replace all of the steam yard switchers. Five classes of Alco yard switchers were purchased between 1931 and 1944, and deliveries of all of them were completed by 1949, with the bulk of the 108 locomotives delivered by 1944.
 
In addition, 3 classes of GE yard switchers were also purchased between 1936 and 1947 comprising another 29 locomotives.
 
The purchase of 10 Lima-Hamilton yard switchers in 1950 dieselized Maybrook and completed the dieselization of all New Haven yard switching.
 
The second major phase of dieselization started with the delivery of the first dual-service Alco DL-109 in 1941. The War Production Board allowed Alco to continue to build additional DL-109s for the New Haven through WWII. In all, 60 units were delivered by 1945 which replaced steam on most mainline passenger and freights.
 
The postwar phase of dieselization began with the delivery of the first of 30 Alco FA-1/FB-1/FA-1 locomotive sets in 1947, literally dieselizing the Maybrook freights in 5 months. Between 1947 and 1951 the New Haven continued almost exclusively with additional Alco lomotives receiving PA-1 and RS 1, 2, and 3 locomotives.
 
As reported in Jack Swanberg's New Haven Power, it was requested the word 'steam' be removed from the schedule covering promotion to engineman in 1948. Steam was officially retired by 1952.
 
Diesel Locomotives are listed by the class designated by the New Haven Railroad:
DER-x: Diesel-Electric Road locomotive
DERS-x: Diesel-Electric Road Switcher locomotive
DEY:-x: Diesel-Electric Yard locomotive

The New Haven Railroad numbered their diesel locomotives with a "0" prefix, to differentiate them from the steam locomotives. By late 1950, with the steam nearly completely retired, they began numbering new diesels without the "0" prefix. 

Layout at a Glance

While my locomotive roster is growing and I'm still gathering some information, I have a pretty good sense of what I want to start with. Due to a mix of passenger service, branchline local service, and through freights running in two directions there is a good mix of motive power on the Highland Line.
 
With my initial (and primary) era of Autumn 1947 I'll be running a representative mix of motive power. I doubt that there was a day in which this specific variety of locomotives ran, but they all would have run in 1947. In general, where a train has multiple runs (such as the Maybrook freights), I'll be using steam for one train and diesel for the second. I have no evidence that a DEY-3 was assigned to the Holyoke freights until 1951. But for now, since the Proto 2000 S-1 model is such a beautiful model I will use that. If/when Atlas retools their S-2 with separately applied details I will use Dey-5 #0606 instead.

Primary (1947) Motive Power Roster
Passenger Trains
  • I-2 #1311
  • I-4 #1383
  • DER-1a #0703
Freight Trains
  • K-1-d #479
  • J-1 #3012
  • L-1 #3228
  • R-1-b #3335
  • DER-2a/b/a #0400/0451/0414
  • DEY-3 #0955
Switching and Work Trains
  • K-1-b #?
  • T-2-b #2446
  • DEY-4 #0802
 

Steam Locomotives

F-5 (2-8-0 Consolidation)
I-1 (4-6-2 Pacific)
I-2 (4-6-2 Pacific)
I-4 (4-6-2 Pacific)
K-1-b (2-6-0 Mogul)
K-1-d (2-6-0 Mogul)
J-1 (2-8-2 Light Mikado)
L-1 (2-10-2 Santa Fe)
R-1-b (4-8-2 Light Mountain)
T-2-b (0-6-0 Switcher)
Stanley S1 (H.K. Porter fireless locomotive)
 
Steam locomotives constituted nearly all of the motive power in 1946. Operating sessions in 1947 will include an increasing mix of diesel power, and by 1948 the majority of motive power will be diesels. From 1949 on, the only steam locomotive in regular operation will be the Stanley S1.
 

Diesel-Electric Locomotives

DER-1a/b/c (Alco-GE DL-109)
DER-2a/b (Alco-GE FA-1, FB-1)
DERS-1b (Alco-GE RS-1)
DERS-2b (Alco-GE RS-2)
DERS-2c (Alco-GE RS-3)
DERS-3 (Fairbanks-Morse H16-44)
DEY-1b (Alco-GE HH660)
DEY-3 (Alco-GE S-1)
DEY-4 (GE 44-tonner)
DEY-5 (Alco-GE S-2)
 
The first diesels for operating sessions will be the DER-1 locomotives on an occasional passenger or freight. Starting in mid-1947 the DER-2s replaced the L-1s on Maybrook freights. In addition, the New Britain switchers were replaced by DEY-4s.
 
Holyoke freights are replaced by DEY-3 or DEY-5s in later 1947. In 1948 the passenger trains begin service with DERS-1b and DERS-2b locomotives. In addition, the DERS-2bs also replace the early DEY locomotives on the Holyoke freights.
 
By 1950, the DERS-2c locomotives begin to replace all other diesels with the exception of DER-1s on train 131 - 136 and the DER-2 locomotives on the Maybrook freights.
 

Motor Cars and Lightweight Trains

The Comet (Goodyear Zeppelin)
RDC-1 (Budd)
RDC-2 (Budd)
RDC-3 (Budd)
The Comet, originally purchased for service between Boston and Providence, was added as train 128-129 from Boston to Waterbury in 1950 before being replaced with conventional locomotive trains. Starting in late 1952 the Budd RDCs began to replace all passenger service through 1953 except train 157 - 472.