Union Pacific Streamlined Heavyweight Cars

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This page was last updated on May 9, 2021.

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In about 1948, and continuing through about 1954, Union Pacific began a program to rebuild at least 108 standard heavyweight cars to match the newer lightweight cars. Included in the rebuild were sealed windows and a fully rounded roof line, with tapered ends, along with smooth sides. In the accompanying roster, these cars are labeled as "Streamlined Heavyweight".

This rebuild program was necessary because the car builders were unable to furnish new cars at the rate the Union Pacific needed new cars. Similar programs were started by other railroads, notably B&O whose modernized cars closely resembled the exterior appearance of UP's cars.

On Union Pacific's modernized cars, the most visual difference on the outside was the tapered roofs at each end to match the height of adjacent modern lightweight cars. The heavyweight cars still had their 14-foot +/- height overall but at the ends they were tapered down to match the adjacent lightweight cars, at approximately 13-feet, 6-inches. The windows were also modernized, similar to windows used on lightweight cars.

The total number of 108 cars were converted between 1946 and 1955, then in 1964, five of the already modernized 3600-series Diner cars were converted to Buffet Lounge cars for service on the Portland Rose; and later assigned to the all-coach Dome Challenger. Since these five cars were converted from already modernized 3600-series Diner cars, the total modernized fleet remained at 108 cars.

Herbert Hanarahan shared this on Trainorders.com on June 14, 2013:

UP 4050 through 4054 were rebuilt to Buffet Lounge Cars and can be easily identified by two smaller rectangular kitchen windows on the fireman's side (when operating kitchen forward) as opposed to the modernized heavyweight diners which had three smaller kitchen windows on the fireman's side. The hall side of both styles of cars were the same. The Buffet Lounge cars could be frequently found on the all-coach section of the "Domeliner Challenger" trains 103 and 104 often operating behind the dome coach to help provide lounge and buffet service and supplement a 5000 series cafe in the same train. Later, they were regularly assigned to the Portland Rose.

Following is a list, taken from the appearance of each group of cars, as shown in the folio diagram illustrations.

Date List

Qty. Type Notes
1946-1948 UP 4607, 4608,
4611, 4613
4 cars Diner (46 seats) Built in 1927; modernized at Omaha in 1948
1948 UP 500-523 24 cars Chair Built in 1928; modernized from UP 400 series at Omaha in 1948
1948 UP 570-579 10 cars Chair Built in 1931; modernized from UP 1200 series at Omaha in 1948
1948 UP 580-595 16 cars Chair Built in 1928-1929; modernized from UP 4200 series at Omaha in 1948
1950 UP 525-536 12 cars Chair Built in 1926; modernized from UP 400 series at Omaha in 1950
1950 OSL 537-541 5 cars Chair Built in 1926; modernized from OSL 707-711 series at Omaha in 1950
1950 LA&SL 542-545 4 cars Chair Built in 1926; modernized from LA&SL 4140-4140 series at Omaha in 1950
1951 UP 3602, 3605, 3606,
3609, 3610, 3612,
3614, 3615, 3616,
3618, 3625, 3626,
13 cars Diner (36 seats) Built in 1926-1929; modernized at Omaha in 1951. (five cars converted to Buffet Lounge in 1964)
1954 UP 1530-1533,
1535, 1537, 1538
7 cars Dormitory Club Built in 1924; modernized at Omaha in 1954
1955 UP 1534 (2nd) 1 car Dormitory Club Built in 1927 as UP 1550; modernized and renumbered at Omaha in 1955
1955 UP 3086-3097 12 cars Baggage Built 1921; converted to Baggage in 1955 from UP 1200 series
1964 UP 4050-4054
(all 2nd)
5 cars Buffet Lounge Converted in 1964 from already modernized UP 3600 series Diners (UP 3616, 3618, 3625, 3626, 3628)

Number List


Of the 13 modernized Diner cars, at least one ended up in Mexico (as CHP 603 "Barranca De Onterros"), possibly one of the three cars (UP 3602, 3604, 3614) sold to Harrison Supply in 1967.

At least two of the modernized car ended up on Blue Mountain & Reading, and were stored at Hamburg, New York, during 2013. The streamlined roofs were removed, at least partially, revealing the steel structure at the tapered ends. Both cars still had the sealed windows, although the glass had long since been removed.

Betterment Cars

Some have used the term "Betterment" to describe these modernized cars, but this term is not seen in any available Union Pacific documents. The term Betterment was a term used by Pullman.

William Kratville described Betterment Cars in his 1968 Pullman Car Catalog: "Betterment cars are those modernized by the company for its own regular or pool use or for special assignment at request of certain roads and include some or all of the following-tight lock couplers, roller bearings, new lighting equipment, full width diaphragms, skirting, special exterior or modernized interior painting and decor, individualized and modernized appointments, two-piece vestibule doors. folding steps, streamlined roof, thermo-pane windows."

The only Betterment cars in Union Pacific service were those assigned to The Forty Niner train in 1937-1941.


UP diagram folio sheets (updated in 1938, 1941, 1943, 1949, 1962, and 1967)

UP Equipment Record Sheets