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NSB Di 3
NSB Di 3
NSB Di 3
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NSB Di 3
HK NOHAB Di 3 006 of the Kosovo Railways
Type and origin
Power typeDiesel–electric
BuilderNydqvist och Holm
Build date1954–1969
Specifications
Configuration:
​
 • UIC
Gauge1,435 mm (4 ft 8+1⁄2 in)
Wheel diameter1,016 mm (40 in)
Length
  • 18.6 m (61 ft 0 in) (a-series)
  • 18.9 m (62 ft 0 in) (b-series)
Loco weight
  • 102 t (100 long tons; 112 short tons) (a-series)
  • 103 t (101 long tons; 114 short tons) (b-series)
Prime moverEMD 567
Cylinders16
TransmissionElectric
Performance figures
Maximum speed
  • 105 km/h (65 mph) (a-series)
  • 146 km/h (91 mph) (b-series)
Power output1,305 kW (1,750 hp)
Tractive effort
  • 265 kN (60,000 lbf) (a-series)
  • 176.5 kN (39,700 lbf) (b-series)
Career
OperatorsInlandsbanan AB
Kosovo Railways
Norwegian State Railways
Ofotbanen AS
Skandinaviska Jernbanor
Number in class35
Numbers
  • 3 602 – 3 633
  • 3 641 – 3 643

NSB Di 3 is a class of 35 diesel–electric locomotives built by NOHAB for the Norwegian State Railways (NSB). The class was built between 1954 and 1969, and delivered in two series, Di 3a and Di 3b. They are based on the Electro-Motive Division F7 and are equipped with EMD 567 engines. They have a distinct bulldog nose and were numbered 602–633 (a-series) and 641–643 (b-series). The locomotives had a prime mover that gives a power output of 1,305 kilowatts (1,750 hp). The a-series has a Co′Co′ wheel arrangement, while the b-series has (A1A)(A1A). The b-series has higher top speed, but lower tractive effort.

The class was the dominant locomotive on NSB's unelectrified lines. It was ordered as part of the company's dieselization of services during the 1950s and 1960s, and was initially used on the three mainline routes of the Bergen, Dovre and Nordland Lines. In the 1960s the Bergen and Dovre Lines were electrified and the Di 3 units transferred to smaller lines, such as the Meråker, Valdres, Røros, Solør and Rauma Lines. They remained in service with NSB until 2001, five years later than planned due to NSB returning their successor, the Di 6. The units are still in use by the private operator Ofotbanen, the Kosovo Railways, an operator in Sicily, and the Norwegian Railway Museum. The class is similar to the DSB Class MY, NMBS Class 52–54, CFL Class 1600 and MÁV M61.

Construction

[edit]
Di 3.626 at Bodø Station in 1991

The first diesel locomotive used by NSB was a single Di 1 unit delivered in 1942. It was more cost-efficient than the steam locomotives used on the non-electrified lines, and in 1945, NSB decided that it would not order more steam locomotives. General Motors' Electro Motive Division (EMD) made a bid to deliver twelve units based on their F7, and NSB agreed to lease a single unit for trial. The body and mechanical components were built by NOHAB, the motors by ASEA and prime mover by EMD. While under production in 1954, GM shipped a G12 for trial in Norway and Sweden. It was tested on the express train on the Dovre Line on 7 August, but proved to have insufficient power, causing the train to be 20 minutes late.[1]

The trial unit from NOHAB was delivered on 17 September 1954. The first test runs in scheduled service were on the Nordland Line between Trondheim and Mo i Rana in October. There were no technical faults until 22 December, when a ground fault [clarification needed] caused the locomotive to be out of service until 17 January. In March the unit was sent back to NOHAB and went on a marketing tour that would eventually reach Ankara, Turkey in 1955.[2]

Two Di 3 units in NSB "Nydesign"

The locomotive returned to Norway on 1 July 1955, where it was numbered 602 and put into service on the Nordland Line.[3] The trials were successful, with much higher regularity than the steam locomotives. The Di 3 was used eight days in a row, and then spent a single day in the depot. NSB signed an agreement with NOHAB for delivery of five further locomotives. This caused a public debate, because the domestic supplier Thune had offered to build a similar locomotive in cooperation with American Locomotive Company. The first delivery was made on 25 April 1957, and the order completed by July. In March 1957 NSB received permission to buy another eight locomotives. Delivery started in October and was completed on 1 June 1958. The order was supplemented with another six trains, with delivery in 1958.[4]

The Finnish State Railways (VR) ordered five units in 1959, but these were cancelled for political reasons. The units were offered to NSB for a reduced price. Three were designated Di 3b because they had a slight specification variation, with a (A1A)'(A1A)' wheel arrangement and higher top speed. Two units had come short enough in the production process that they could be given the same specifications as the other Di 3a units, but received a slightly longer body. The Di 3b were given the numbers 641–643. For part of 1960, no. 623 was leased by NOHAB and sent on a demonstration tour in Eastern Europe. This resulted in an order from the Hungarian State Railways, where it became the MAV M61. The Røros Line was upgraded and the Bergen Line units transferred to Trondheim in 1960, but increased need for hauling forced NSB to not use the units on the Røros Line until the delivery of the next batch of six units in 1965. The final delivery, of four units, was made in 1969.[5]

Operation

[edit]
NSB Di 3.616 at Trondheim Central Station preparing for departure on the express train on the Nordland Line in 1986

The initial use for the Di 3 was to operate the three non-electrified long-distance lines of NSB: the Bergen Line, the Dovre Line and the Nordland Line.[6] Following the delivery of the first batch in 1957, they were from 2 June used on the Dovre Line, north of Otta to Trondheim, and further north along the Nordland Line to Mo i Rana. The stock was sufficient to replace all steam locomotives on the Nordland Line, and reduced travel time by one hour. From Hamar to Otta, the track did not have sufficient permitted axle load.[7] From the second batch of eight units, five were put into service on the Bergen Line, the rest on the Dovre and Nordland Lines. Necessary upgrades of the permitted axle load had been made to the Dovre Line and Nordland Line, and the locomotives were in use from Hamar Station to Saltdal. On 30 November, the Nordland Line was completed to Fauske, and the full length operated with Di 3.[8]

The first section of the Bergen Line, the Gjøvik Line and the Roa–Hønefoss Line, was electrified in February 1961. This allowed diesel and electric locomotives to haul all trains from Oslo to Bergen. In 1962 the Nordland Line was completed to Bodø Station, but the increased need for locomotives was more than compensated by the electrification of the Bergen Line being extended to Ål Station. The first Di 3 ran on the Røros Line in 1964, that had previously been denied due to bridges with insufficient axle load permits.[9] In 1965, the Bergen Line was electrified, and all but one Di 3 was transferred to Trondheim. A single unit, usually no. 610, was stationed at Finse Station as a snowplow. Along with additional deliveries, there were sufficient Di 3 units to terminate most steam operations.[6]

After the Bergen Line was electrified, the work continued on the Dovre Line. The section from Hamar to Otta was finished in 1967, and the following year to Dombås Station. This allowed the locomotives to be transferred to secondary lines. With the final delivery of the last units in 1969 and the completion of the electrification of the Dovre Line in 1970, the final steam locomotive was taken out of service.[9] During the last half of the 1960s, the Di 3 was put into service on the Rauma Line, the Røros Line, the Solør Line, the Valdres Line and the Meråker Line.[6]

NSB Di 3.633 at Fagernes Station in 1986

In November 1970, the Dovre Line was electrified, and the last steam locomotives were retired. A long-term plan to electrify half the lines was finished, and for two decades, NSB's operations were very stable with no major investments to infrastructure or closing of lines. NSB had slightly fewer diesel locomotives than they needed, but plans to order additional Di 3 was never fulfilled. In 1981, NSB took delivery of five Di 4 to supplement the older units.[10] They were mainly used on the Nordland Line, and Di 3 units were predominantly used on the other lines, although they continued to operate som trains on the Nordland Line. On 1 April 1987, a Di 3 612 caught on fire; the damage was small enough that it could have been repaired, but NSB instead decided to put aside the unit. At the time NSB planned to order additional Di 4, but these plans were put on hold. In 1988, the Valdres Line was closed; this was the only time a line with Di 3 in regular service was closed.[11]

During the 1980s, NSB started leasing SJ T44-locomotives from Sweden to supplement the Di 3. In 1992, the decision was made to order 12 Di 6 and 20 Di 8 to replace the Di 3. The former was based on the Di 4 and had twice the power of the Di 3. The Di 8 was slightly more powerful than the Di 3, and were intended for freight trains. Both series were put into service in 1996, but the Di 6 proved to have so many technical problems that they were returned to Siemens in 1998. The Di 3 units had been set aside and some had been scrapped, but the return of the Di 6 forced NSB to put the units back into service.[5]

An ore train of the Kosovo Railways being hauled by no. 008

During the mid-1990s, NSB had initiated a program to replace the traditional locomotive and carriage trains with new, tilting multiple units. This had led to the order of sixteen Class 73 four-car units for the three mainline routes on the Bergen Line, Dovre Line and Sørland Line. To supplement this, the board of NSB decided on 14 November 1996 to purchase seven tilting diesel multiple units for the Røros and Rauma Lines. The choice fell on Class 93, with fifteen units eventually delivered. This allowed all passenger trains on diselized lines to either be operated with Class 93 be hauled by the Di 4.[12] The last Di 3-hauled train ran on 7 January 2001.[9]

Post-NSB

[edit]

With the delivery of Class 93, NSB started to retire or sell the Di 3. In November 2001, five units were sold for NOK 250,000 each—well under market price—to the new private operator Ofotbanen. The purchase raised controversy, because the potential operator Banetransport had offered full market price for the trains.[13] One year after delivery, six of eleven Class 93-locomotives were out of order.[14] To solve the problem, NSB had to rent back used Di 3 locomotives from Ofotbanen. NSB had chosen to sell the old locomotives for less than market price, but Ofotbanen demanded that NSB pay the entire purchase price for the short-term rental back.[15]

Four units (619, 633, 641 and 643) were sold to the United Nations and was put into service in Kosovo, in what has since become the Kosovo Railways. Four units (622, 626, 630 and 631) were sold to an operator in Sicily, Italy. The Norwegian National Rail Administration bought one unit (628) for maintenance, and has painted it yellow. The Norwegian Railway Museum in Hamar has preserved four units (602, 615, 616 and 642), of which two (602 and 616) were operated by GM-Gruppen and one (615) is kept for spare parts. NSB has kept one unit as reserve at Ål Station. The remaining units have been scrapped, put aside or sold as spare part units.[9]

Specifications

[edit]
Two Di 3 units Ofotbanen design

The Di 3 was built by Nydquist och Holm of Trollhättan, Sweden, as part of a series of GM EMD AA16 locomotives in Europe. They are technically similar to the DSB Class MY of Denmark and the MAV M61 of Hungary. The locomotives are powered by a 16-cylinder EMD 16.567 C or E engine that has a power output of 1,305 kilowatts (1,750 horsepower) at 835 revolutions per minute (rpm). The engines power an EMD D32 or D12 generator that feeds six ASEA LJB76 or LJB84 motors on a Di 3a. The Di 3b is equipped with four EMD D40 or D77B motors. This gives a tractive effort of 265 kilonewtons (60,000 lbf) for the a-series and 176.5 kilonewtons (39,700 pounds-force) for the b-series. The motors have a power output of 1,100 kilowatts (1,500 horsepower). The maximum speed is 105 kilometres per hour (65 mph) for the a-series and 143 kilometres per hour (89 miles per hour) for the b-series.[5][16]

The steel bodies are 18.60 or 18.90 metres (61.0 or 62.0 ft) long. The longer length is for the three b-series units and the two a-series locomotives that were made in the batch, originally intended for VR. The a-series has a Co'Co' wheel arrangement, while the b-series has a (A1A)'(A1A)' arrangement, where the center of the three axles on each bogie is unpowered. The wheels have a 1,016 millimetres (3 ft 4.0 in) wheel diameter and the locomotives have a weight of 102.0 tonnes (100.4 long tons; 112.4 short tons) for the a-series and 103.0 tonnes (101.4 long tons; 113.5 short tons) for the b-series. The trains can be run in multiple with the Di 4, Di 6 and Di 8. All the Di 3 engines featured a bulldog nose, the only locomotive type in Norway to do so.[16] The locomotives were at first delivered in a dark green livery, but during the 1960s this was changed to red, and the last delivered units never had a green scheme.[6]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

NSB Di 3

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The NSB Di 3 is a class of 35 diesel-electric locomotives built by the Swedish manufacturer NOHAB for the Norwegian State Railways (NSB), with deliveries spanning from to 1969. Powered by 16-567 series engines producing between 1,700 and 1,900 horsepower, the class was designed primarily for mixed and freight services on Norway's non-electrified main lines, where it played a pivotal role in replacing steam locomotives during the post-World War II dieselization efforts. The locomotives featured a distinctive "bulldog nose" design and were divided into two main subclasses: the Di 3a (32 units) with a Co'Co' , 102-ton weight, and maximum speed of 105 km/h, suited for heavy freight; and the Di 3b (3 units) with an A1A-A1A arrangement, lighter 70-ton weight, and higher top speed of 143 km/h (later derated to 105 km/h) for faster duties. Introduced as part of NSB's "Get-rid-of-the-steam" initiative, the Di 3 class emerged from successful trials of a demonstrator in 1954, leading to the order of these robust units to modernize operations on lines such as the and Røros Line. Over their , which extended into regular use until 2001 and occasional duties beyond, the Di 3s hauled a wide range of trains, including express passenger services and heavy freight, proving highly reliable in Norway's challenging terrain and weather conditions. Their longevity—spanning more than four decades—made them the backbone of NSB's diesel fleet until the introduction of more modern classes like the Di 6 and Di 8 in the late 1990s. Following withdrawal from NSB service, several Di 3 locomotives were preserved for heritage operations, with examples like unit 603 now held by the Norwegian Railway Museum, while others were exported to operators in , (), and private lines such as Ofotbanen for continued freight work or repurposed as snowplows and maintenance units. The class's enduring legacy lies in its contribution to Norway's railway transition from steam to diesel power, symbolizing a era of efficient, versatile motive power that supported in remote regions.

Background and Development

Historical Context

Following , the Norwegian State Railways (NSB) faced significant economic and operational challenges with its aging fleet, which suffered from low of only 5-10% and costs due to wear from wartime and usage. These pressures, compounded by the need to modernize the rail network amid Norway's economic recovery, prompted NSB to initiate a comprehensive dieselization program in the 1950s as part of the national "Vekk med dampen" ("Away with steam") initiative approved by parliament in 1955. The program aimed to replace steam traction on non-electrified lines, such as the , , and , where electrification was deemed too costly or impractical in the short term, offering diesel's advantages in (around 30%), reduced crew requirements, and lower operational downtime compared to steam. To address these needs, NSB began evaluating imported designs in the early , focusing on reliable, versatile units capable of handling mixed freight and services on rugged . In , as a key step, NSB conducted its first diesel trials using a demonstrator unit built by NOHAB under license from ' Electro-Motive Division (EMD), tested on the between and . This evaluation, part of a comparative procurement of three locomotives from NOHAB, MaK, and KHD, highlighted the superior of the EMD-inspired in Norwegian conditions, paving the way for its adoption over hydraulic alternatives. The trials confirmed diesel's potential to streamline operations and cut costs, influencing NSB's strategic shift toward diesel-electric technology for non-electrified routes.

Ordering and Construction

In 1954, the Norwegian State Railways (NSB) initiated the of diesel-electric locomotives to replace aging traction on non-electrified lines by ordering three units from different manufacturers for comparative testing: one from Nydqvist & Holm (NOHAB) in , one from (MaK) in , and one from Klöckner-Humboldt-Deutz (KHD) in . The NOHAB prototype, constructed under from ' Electro-Motive Division (EMD) and influenced by the design, proved superior in performance and reliability during trials, leading NSB to select it as the basis for the Di 3 class; this unit, originally NOHAB works number 2246, was delivered on , 1954, and later purchased by NSB in 1957 as Di 3 no. 602. Following successful evaluation, NSB placed follow-on orders exclusively with NOHAB for production units, with deliveries spanning 1957 to 1969: six Di 3a locomotives (nos. 603–608) in 1957, thirteen (nos. 609–621) in 1958, two (nos. 622–623; originally ordered by but rejected by the Finnish State Railways due to gauge incompatibility) in 1960, six (nos. 624–629) in 1965, and four (nos. 630–633) in 1969, bringing the Di 3a subclass to a total of 32 units including the . In 1960, NSB acquired three upgraded Di 3b variants (nos. 641–643), the remaining units from the same 1959 order for the Finnish State Railways (VR) that included nos. 622–623 (completed as Di 3a), but rejected due to gauge incompatibility; these units featured modifications for higher speed and were integrated into NSB service, completing the class at 35 locomotives overall. Construction occurred at NOHAB's facility in , , where the locomotive bodies and mechanical components were fabricated to European loading gauge standards; the prime movers (EMD 16-567 series diesel engines) and electrical systems were supplied from EMD in the United States, shipped to Sweden for final assembly and integration with Swedish-built traction motors.

Design and Variants

Mechanical Design

The NSB Di 3a locomotives featured a distinctive bulldog nose cab design, licensed from the Electro-Motive Division (EMD) model, which provided enhanced visibility and structural integrity for operations in challenging environments. This cab configuration, with its protruding nose and narrow front windows, contributed to the locomotive's iconic appearance while prioritizing durability. The Di 3a employed a Co’Co’ , utilizing six powered axles to maximize traction on steep gradients typical of Norwegian non-electrified lines. The frame and body were constructed from welded , offering robustness against the harsh Nordic weather conditions, including heavy snow and ice. This all-welded design ensured a rigid structure capable of withstanding the stresses of mixed freight and passenger services over rugged terrain. The overall length over buffers measured 18.6 meters, providing ample space for the locomotive's components while maintaining stability. Bogie design emphasized high , with three-axle trucks featuring roller bearings and a rigid frame to handle variable loads on uneven, non-electrified tracks. These bogies, adapted from EMD's proven , supported reliable performance across diverse operational demands without compromising ride quality. The system included a capacity of approximately 3,500 liters (equivalent to 2.9 metric tons of diesel), stored in underframe tanks, with integrated cooling systems optimized for climates to prevent fuel gelling and maintain engine efficiency. Safety features incorporated , an innovation from the EMD lineage that converted into electrical resistance for controlled deceleration on descents. The cab were tailored for long-haul operations, with intuitive control layouts and protective enclosures to reduce operator during extended runs in adverse conditions. The locomotives were powered by a 16-567 series prime mover.

Subclass Differences

The NSB Di 3 class comprised two main subclasses, Di 3a and Di 3b, with the latter incorporating engineering adaptations for enhanced passenger service capabilities on non-electrified secondary lines. The Di 3a subclass consisted of 32 locomotives numbered 602 to 633, built between 1954 and 1969 by Nydqvist & Holm (NOHAB) in , , using components. These units featured a Co′Co′ wheel arrangement with six powered axles, optimized for freight and mixed-traffic duties, and a maximum speed of 105 km/h. Engine variants evolved over production: early units (602) used the 16-567B model at 1,700 hp, while later batches progressed to 16-567C (603–623, 1957–1959), 16-567D1 (624–629, 1965), and 16-567E (630–633, 1969), all delivering up to 1,775 hp. In contrast, the Di 3b subclass included only three locomotives, numbered 641 to 643, constructed in 1958–1959 and originally ordered for the Finnish State Railways but redirected to NSB in 1960. These featured an (A1A)′(A1A)′ with four powered axles across two bogies, reducing weight to 70 tons for while enabling smoother high-speed operation, and an overall length of 18.9 meters. Equipped with the 16-567C engine at 1,775 hp, the Di 3b incorporated higher final drive gearing for a top speed of 143 km/h (later derated to 105 km/h for operational consistency). Specific modifications included increased water capacity of 4.4 tons (versus 3.3 tons in Di 3a) to support heating for longer passenger runs. The production of Di 3b addressed growing demands for faster passenger services on NSB's unelectrified routes following the expansion of in the , which shifted diesel needs toward mixed-traffic roles on branch lines. This subclass represented a targeted evolution from the standard NOHAB design heritage shared with Di 3a, emphasizing velocity and ride quality over raw freight .

Technical Specifications

Power and Performance

The NSB Di 3 class locomotives feature a GM EMD 16-567C V16 as the prime mover, delivering 1,900 horsepower (1,415 kW) at 835 rpm, with 1,305 kW (1,750 hp) of continuous power available at the rail. This power is transmitted through a diesel-electric system, utilizing DC generators coupled to the engine that supply current to six traction motors, enabling efficient torque delivery for freight and operations. The design draws from EMD's proven F-series , licensed to NOHAB for , ensuring reliable in demanding mixed-traffic roles. Fuel efficiency for the 16-567C is approximately 200–220 g/kWh under load, supporting extended operations with a capacity of around 2,900 kg (3,400 liters), sufficient for ranges exceeding 800 km depending on and terrain. Performance metrics include a starting of 265 kN (60,000 lbf) for the Di 3a variant, allowing effective acceleration on inclines up to 20‰, such as those on the , where the locomotive was primarily deployed. The Co′Co′ of the Di 3a enhances traction on slippery or graded tracks compared to the A1A-A1A setup of the Di 3b, contributing to stable hauling of heavy trains. weight is 102 tonnes for Di 3a and 70 tonnes for Di 3b. Braking is provided by a combination of dynamic braking—where traction motors act as generators to dissipate energy—and air brakes for precise control and emergency stops, standard in EMD-derived designs. Adaptations for Norwegian conditions include cold-start capabilities inherent to the robust two-stroke engine, which operates reliably in sub-zero temperatures, and protective grilles on windscreens to guard against ice falls from bridges and tunnels. Additionally, snow-resistant air intake filters and the locomotive's use as a pusher for rotary snow plows at high-altitude sites like Finse demonstrate its resilience in harsh winters.

Dimensions and Components

The NSB Di 3 locomotives feature compact dimensions suited to Norwegian , with the Di 3a subclass measuring 18.6 meters in over the buffers, 4.1 meters in , and 3.0 meters in width. The Di 3b subclass is slightly longer at 18.9 meters, maintaining the same and width for consistency across variants. Service weights for the locomotives are 102 tonnes for the Di 3a and 103 tonnes for the Di 3b, with an of approximately 17 tonnes in both cases to ensure compatibility with standard tracks. These weights reflect the adhesion-focused design, where the Di 3a utilizes all six axles for traction under a Co'Co' , while the Di 3b employs an (A1A)-(A1A) arrangement with four powered axles.
ParameterDi 3aDi 3b
Length over buffers18.6 m18.9 m
Height4.1 m4.1 m
Width3.0 m3.0 m
Service weight102 tonnes103 tonnes
17 tonnes17 tonnes
Key auxiliary components include six traction motors rated at 220 kW each, providing the primary propulsion in the diesel-electric system. The main generator delivers an output of 1,500 kW to power these motors, driven by the GM 16-567C prime mover. Battery systems support startup and low-speed operations, integrated with standard control electronics for throttle and functions. The locomotives are equipped with standard Norwegian UIC buffers and screw couplers, ensuring with European on mixed-gauge networks. protocols specify overhauls every 500,000 km to sustain reliability on non-electrified lines.

Operational History

NSB Deployment

The NSB Di 3 locomotives entered service in as the primary diesel power for non-electrified lines, fulfilling the railway's "Get rid of the " initiative launched in to phase out steam operations. The initial batch of five units (Nos. 603–607) was assigned to the depot and immediately deployed on key routes including the , , and for hauling both freight and mixed passenger trains, effectively replacing older steam classes such as the NSB Class 47. These locomotives proved reliable for heavy mixed-traffic duties, with their robust design enabling consistent performance on demanding mountain gradients and long-distance hauls. By the early 1960s, the fleet had expanded to support the extension of the to in 1962, where Di 3 units handled increased freight volumes, including timber and industrial goods, alongside passenger services on lines like Rauma, , and . The Di 3a subclass dominated mixed-traffic assignments across these routes, while the Di 3b variants, introduced later, were optimized for express passenger services on the . Crew training programs, initiated in 1955 alongside the dieselization push, emphasized operation in Norway's harsh terrain, with early focus on Trondheim-based personnel to ensure smooth transition from . Operational challenges included structural limitations on older infrastructure, such as weak bridges on the and Hamar–Otta sections, necessitating upgrades to accommodate the locomotives' weight. Following the electrification of major lines like by 1964, the Di 3 fleet reached its peak deployment in the and on secondary non-electrified routes, including , Rauma, Trenteløbanen, Meråker, Solør, and , where they monopolized freight transport—particularly on lines like Meråker—until the introduction of Di 4 units in 1981. By 1969, all 35 locomotives were in service, with assignments distributed across depots: 17 at , six at , and two at , later shifting northward to and Meråker for sustained freight dominance. Major overhauls in the at NSB workshops in addressed wear from intensive use, extending service life amid growing timber export demands. Winter operations required adaptations like enhanced snow plows on select units, though the class's inherent durability supported year-round reliability on exposed lines.

Retirement from NSB

Some units were withdrawn earlier in the mid-1990s, but the retirement of the NSB Di 3 class accelerated in the late 1990s as the Norwegian State Railways prioritized projects and introduced newer electric multiple units for passenger services on non-electrified lines, reducing the demand for diesel locomotives. The class 93 units gradually replaced the Di 3 on routes such as the , Rauma, and Lines, where the Di 3 had been a mainstay for mixed traffic. By the early , ongoing efforts further diminished their role, with electric locomotives like the El 18 handling heavy freight on upgraded lines, marking the end of the Di 3's prominence in NSB's fleet. The decommissioning process accelerated in 2000–2001, with approximately 10 units scrapped primarily for spare parts to support the remaining active locomotives. Several locomotives were stored at various depots, including Narvik, awaiting sale or disposal as NSB phased out the class. One notable incident contributing to scrapping was the wrecking of unit 625 in the Åsta accident on January 4, 2000, which was dismantled on site. Economic pressures played a key role in the retirement, as the aging EMD 567 engines in the Di 3 fleet incurred high maintenance costs compared to modern alternatives, including electric units that offered lower operating expenses on electrified networks. The two-stroke design of the series, while reliable in its prime, became increasingly expensive to maintain after decades of service, prompting NSB to accelerate withdrawals. The final milestones for NSB operation occurred in late 2000 and early 2001, with the last scheduled passenger run on December 26, 2000, on the Røros Line using units 623 and 629. Sporadic reserve duties continued until January 7, 2001, after which Di 3 locomotives were no longer permitted in regular NSB service; unit 629 hauled the final such train to on January 6. Unit 633, among others, was withdrawn around this period, facilitating the transition to private operators who acquired surplus units at reduced prices.

Post-NSB Service and Preservation

Export and Current Use

Following the withdrawal of the NSB Di 3 locomotives from primary service, several units were exported for continued freight and mixed-traffic operations between 1998 and 2005. In 2001, six units (603, 621, 623, 629, 632, and 642) were sold to the private operator Ofotbanen AS for iron ore freight and passenger services on the Ofoten Line in northern Norway. These locomotives were transferred to Narvik via Sweden in early 2003 and initially used for tourist excursions on the Ofoten Line to Kiruna. Following Ofotbanen AS's bankruptcy in 2010, most units were sold to Swedish operators, including Inlandsbanan (603, 621, 623, 632) and Skandinaviska Jernbanor (629 in Östersund); unit 642 served as a spare parts donor before preservation. As of 2025, no Di 3 units operate on the Ofoten Line, which is now served by electric locomotives under Cargonet. Concurrently, four units (619, 633, 641, and 643) were donated to Kosovo Railways (now Trainkos) in January 2001 as part of post-conflict support, where they were renumbered and employed for mixed freight and passenger duties on the non-electrified network. Between 2000 and 2001, another four units (622, 626, 630, and 631) were sold to the Sicilian operator Impresa Salvatore Esposito (associated with Ferrovie Nordiche Siciliane) for construction and maintenance trains on the island's standard-gauge lines. As of 2025, the four exported units to remain in use for mixed-traffic roles where reported, supporting the rehabilitation of key lines like Fushë Kosovë to Mitrovica, though they face integration with newer EU-funded infrastructure upgrades. In Sicily, the units have transitioned to heritage and work train roles, with three survivors (622, 626, and 631) retaining their NSB red livery and used sporadically for services; last confirmed operations as of 2019, with presumed continued activity per operator records; unit 630 was scrapped following a 2006 . Recent operations in as of 2025 include veteran driver training programs on preserved Di 3 units, highlighting their enduring reliability for non-electrified routes. However, private operators report ongoing maintenance challenges due to parts scarcity for the aging NOHAB-built components, often relying on cannibalization from donor locomotives or aftermarket adaptations. In export destinations, adaptations have included signaling upgrades for local systems in and , as well as minor modifications for compatibility with regional freight protocols, without altering the standard-gauge bogies. A total of 14 Di 3 units were scrapped, primarily in the 2000s, to provide spare parts for the surviving fleet; notable examples include units 604, 606, 607, and 612, withdrawn between 1995 and 2000 due to accidents or wear.

Preservation and Legacy

Several Di 3 locomotives have been preserved at the Norwegian Railway Museum (Norsk Jernbanemuseum) in , serving as key exhibits in the institution's collection of diesel-era . The museum holds units 602, 616, and 642, acquired in 1997, 1997, and 2014 respectively, with 602 and 616 maintained in operational condition for heritage demonstrations. Unit 602, the prototype introduced in 1954 as a demonstrator, underwent restoration in the early for the Norwegian railway system's 150th anniversary celebrations in 2014. Restoration efforts for these preserved units have been led by the in collaboration with volunteer groups, including the Norwegian Railway Club (Norsk Jernbaneklubb), focusing on periodic overhauls during the 2010s and beyond. For instance, unit 616 received inspections and major maintenance in 2019 to ensure operational readiness. In 2025, the restored Di 3a subclass unit 616 participated in special runs, including one along the Kongsvinger Line in May, highlighting ongoing preservation activities. Maintenance remains volunteer-driven, with challenges arising from the scarcity of replacement parts for the , an obsolete design requiring custom sourcing or fabrication. The Di 3 class holds enduring historical significance as an icon of Norway's mid-20th-century diesel transition, symbolizing the shift from steam power on non-electrified lines and remaining the primary type until the introduction of more powerful successors like the Di 4 in 1981. Its robust design and long influenced the development of later NSB diesel classes, establishing benchmarks for reliability in harsh Nordic conditions. The have also left a cultural mark, appearing in Norwegian media depictions of rail history and inspiring detailed scale models from manufacturers such as Märklin, popular among European model railroad enthusiasts. Commemorative events featuring preserved Di 3 units underscore their legacy, with the Norwegian Railway Museum organizing heritage excursions such as test runs and tours on lines like the Rauma Line. Notable examples include a 2023 railtour with unit 642 from to and participation in the Rauma Line's centenary celebrations in 2024 using units 602 and 616, evoking the class's original operational role on scenic routes.

References

  1. https://sando.co/index.php?aut=&vis=252&nid=2&engelsk=1
  2. https://www.roundnoses.com/themes/norway.html
  3. https://digitaltmuseum.no/011013117203/diesellokomotiv-di-3-603
  4. https://sando.co/index.php?nid=2&vis=252&uv=4
  5. https://www.loco-info.com/view.aspx?id=13070&t=type
  6. https://www.socimi.it/nsb-norges-statsbaner-norwegian-state-railways/
  7. https://www.loco-info.com/view.aspx?id=-910&type=Country
  8. https://trainweb.us/dombas/di3.html
  9. https://www.railfaneurope.net/pix/no/diesel/Di3/630-643/pix.html
  10. https://www.nohab-gm.hu/en/en05_1.html
  11. https://www.nohab.hu/nsbpics.html
  12. https://bmrrhs-new.squarespace.com/s/EMD-SPEC-LOCO-F7A-F7B-1948.pdf
  13. https://loco-info.com/view.aspx?id=13070&t=type
  14. https://www.marklin-users.net/intruder/Svein/Tog/Sites/N/Di3Marklin.html
  15. https://www.neptunus-power.com/diesel-engine/emd-567/
  16. https://www.tt-forums.net/viewtopic.php?t=62792
  17. http://lolkebijlsma.com/di3/di3.shtml
  18. https://www.rypn.org/articles/layout/060301cook/default.htm
  19. https://utahrails.net/pdf/EMD_567_History_and_Development_1951.pdf
  20. https://www.railwaygazette.com/news/back-to-builder/28853.article
  21. http://jernbanemuseet.no/wp-content/uploads/2017/03/Materielliste_diesellokomotiver-digimus-2017.pdf
  22. https://jernbanemuseet.no/21131-2/
  23. https://jernbanemuseet.no/boggikontroll-pa-di-3-616/
  24. https://www.instagram.com/p/DQMgh57CD8N/
  25. https://www.facebook.com/groups/1364027197364916/posts/1998939757206987/
  26. https://www.walthers.com/nohab-class-di3-diesel-3-rail-w-sound-digital-norwegian-state-railways-nsb-era-iii-brown-yellow-silver
  27. https://jernbanemuseet.no/provekjoring-med-trippel-di3/
  28. https://www.facebook.com/groups/2121268674761013/posts/3845721262315737/
  29. https://www.youtube.com/watch?v=KRekDpHE5A0
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