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Union Pacific Railroad

Roster of Road Slug Units

This page was last updated on August 24, 2014.

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Road Slug Model S4-B -- 1 unit
B-B trucks; 249,000 pounds operating weight

Road
Number
First
Number
Rebuild
Date
Rebuilt
From
Date To
S50
New
Number
Date To
New Number
UP S50 MKT 501 Jul 1982 MKT GP40 222 20 Mar 1989 S300 1 Feb 1991

General Notes:

a. Built as MKT road slug 501 from wrecked MKT GP40 222; renumbered and repainted to UP S50 on 20 March 1989, at the same time as matching GP40 slug control units, UP 595 and 596 (ex MKT 226, 227).
b. Operated with UP 3000 and 3001, former MKT GP40s.
   

Road Slug Model S4-B -- 1 unit
B-B trucks; 249,000 pounds operating weight

Road
Number
First
Number
Second
Number
Rebuild
Date
Rebuilt
From
Date To
S50
Date To
S300
Date To
UPY 926
UP S300 MKT 501 UP S50 Jul 1982 MKT GP40 222 20 Mar 1989 1 Feb 1991 17 Dec 2003

General Notes:

a. Built as MKT road slug 501 from wrecked MKT GP40 222; renumbered and repainted to UP S50 on 20 March 1989, at the same time as matching GP40 slug control units, UP 595 and 596 (ex MKT 226, 227).
b. Operated with UP 3000 and 3001, former MKT GP40s.
c. Model was changed from SL-1 to S4-B on 14 April 1992; changed from freight service to switching service on same date.
d. Renumbered to UPY 926.
   

Road Slug Model S5-2B -- 3 units
B-B trucks; 256,000 pounds operating weight

Road
Number
Rebuild
Date
Rebuilt
From
UPY
Number
Date To
UPY Number
UP S301 5 Apr 1991 KCS GP30 4104 UPY 927 30 Apr 2001
UP S302 5 Apr 1991 KCS GP30 4108 UPY 928 29 Mar 2001
UP S303 5 Apr 1991 KCS GP30 4119 UPY 929 19 Feb 2002

General Notes:

a. Rebuilt from retired KCS GP30s by Morrison Knudsen, Boise, Idaho.
b. Equipped with 2,600 gallon fuel tanks, and pumping equipment to transfer fuel between slug and attached slug control units; sensing monitors activate the pumps to keep fuel level equalized between the control units and the slug.
c. All three road slugs operate with UP GP40-2 slug control units.
d. Renumbered to UPY 927-929.
   

Road Slug Model S3-3BDE -- 1 unit
B-B trucks; 280,000 pounds operating weight

Road
Number
First
Number
Rebuild
Date
Rebuilt
From
Date
Retired
(UP S310) SP 1600 1 May 1980 UP U25B 634 25 Jul 2000

General Notes:

a. One unit to UP at merger, numbered SP 1600.
b. SP 1600 built by Morrison-Knudsen from UP U25B 634 (retired by UP in September 1972, sold to MK in August 1974) as a prototype for SP's own planned road slug program; the MK rebuilding included new step wells and a new low carbody, with new sand boxes and extra ballast.
c. Equipped with 2900-gallon fuel tank and pumping equipment to transfer fuel from the slug and the attached control units; sensing monitors activate the pumps to keep the fuel level equalized between the control units and the road slug.
d. Former SP designation was TEBU (Tractive Effort Booster Unit).
e. Equipped to operate with former SP 7940-7959 group GP40-2s (built in April and May 1980) and former SSW 7960-7966 group GP40s (rebuilt in 1981 and 1982).
f. Stored by UP at North Platte, Nebraska, during late 1998.
g. Assigned UPY 930, not renumbered prior to being retired.
   

Road Slug Model S3-2B -- 10 units
B-B trucks; 280,000 pounds operating weight

Road
Number
First
Number
Rebuild
Date
Rebuilt
From
Date To
UP Number
UPY
Number
Date To
UPY Number
Date
Retired
Notes
(UP S311) SP 1601 1 May 1981 SP U25B 6761       25 Jul 2000  
(UP S312) SP 1602 29 May 1981 SP U25B 6765       26 Mar 1997 1
UP S313 SP 1605 Aug 1981 SP U25B 6747 19 Jan 1998 UPY 932 14 Jan 2004    
(UP S314) SP 1606 Sep 1981 SP U25B 6712       28 Dec 1999  
(UP S315) SP 1608 Nov 1981 SP U25B 6711       25 Jul 2000  
(UP S316) SP 1609 Dec 1981 SP U25B 6713       25 Jul 2000  
(UP S317) SP 1610 Jan 1982 SP U25B 6751       26 Mar 1997 2
UP S318 SP 1611 Mar 1982 SP U25B 6754 27 Jul 1999 UPY 936 14 Jan 2004    
UP S319 SP 1612 May 1982 SP U25B 6758 18 Sep 1997 UPY 937 29 Aug 2003    
(UP S320) SP 1613 Jun 1982 SP U25B 6766       25 Jul 2000  

General Notes:

a. Original total of 13 units; 10 units went to UP at merger; SP retired three units (SP 1603, 1604, and 1607) prior to the merger.
b. SP's road slugs were rebuilt by its Sacramento shops from the road's own retired U25Bs.
c. Equipped with 2900 gallon fuel tank and pumping equipment to transfer fuel from the slug and the attached control units; sensing monitors activate the pumps to keep the fuel level equalized between the control units and the road slug.
d. Former SP designation was TEBU (Tractive Effort Booster Unit).
e. Equipped to operate with former SP 7940-7959 group GP40-2s (built in April and May 1980) and former SSW 7960-7966 group GP40s (rebuilt in 1981 and 1982).
f. SP 1601, 1608, 1609, 1613 stored by UP at North Platte, Nebraska, during late 1998.
g. UP S319 (ex SP 1612) was the first of this group to be repainted to Union Pacific, completed on 18 September 1997.
h. Renumbered to UPY 931-938.

Notes:

1. SP 1602 was sold to National Railway Equipment on 28 April 1977.
2. SP 1610 was sold for scrap to Louisville Scrap, 28 February 1998.

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