1. Description

2. Refurbishment

3. The DT3-LZBs

4. Today

5. Gallery

6. References

7. External links

The Type DT3 is a three-car electric multiple unit train built for the Hamburger Hochbahn. They were first introduced in 1968 to replace the 1911-1929 built T cars and to speed up the journey times on the U1 line.

Description

With the continued expansion of the subway network in the 1960s and 70s, and the desire for greater efficiency in operating procedures resulted in development of a new type of subway units based on the older DT1 and DT2 units. The DT3 resembles to the DT2 in appearance but shows many technical differences. Technically the DT3s were based on the DT1s which were compatible to DT3 after some customization, both types can be coupled. Instead of two cars the DT3 feature a third car which is 10.72 meters long. Because of the greater overall length of a 9-car train made up of three units instead of an 8-car train made up of four units of DT1s or DT2s some platforms on the U1 line (e.g. on the Langenhorn branch) had to be extended. The DT3 trains are more powerful than its predecessors; they have been equipped with additional traction motors and therefore have got a much stronger acceleration. Thus, the maximum acceleration is 1.2 m/s², in contrast to the DT2 with 0.8 m/s². Moreover, the speed limit was increased to 80 km/h (50 mph) again, because the units were mainly built for the longest subway line in Hamburg, the U1 line.^[2]

Refurbishment

In the mid-1970s the cars got loudspeakers inside and on the roof outside for station announcements. After a first small refurbishment in the early 1980s, in the 1990s many of the units have been rebuilt and received a newly designed front and a new interior design, such as windows between the cars and between the driver's cab and passenger interior. The rebuilt became necessary due to structural issues the DT3 faced just like their predecessor as both types were actually only designed for a lifespan of 20 years. A total of 68 units were involved into the refurbishment, the rest of the units were replaced by new DT4 units, retired and scrapped between 1996 and 2003. The rebuilt units are now called DT3E. ^[3]

In June 2015, the operator Hochbahn announced another refurbishment for ten DT3E units to extend their lifespan for ten more years.^[4] This refurbishment will also include the withdrawal of the old electromechanical propulsion control which will be replaced by a modern electronic control. This improvement is going to make the refurbished cars incompatible to the other DT3E, thus they will be given the name "DT3N" to distinguish them from non-refurbished cars.

The DT3-LZBs

For experiments with driverless trains on a larger scale, the six units 9963/64/65-9978/79/80 (now 921-926) have been converted for automatic operation. After a long trial run on the test track parallel to the U1 line between the maintenance workshop Farmsen and Berne station, the six now called DT3-LZB units were used between Volksdorf station and Großhansdorf station on the Walddörferbahn branch for driverless operation. The automatic operation was observed by a conductor permanently sitting in the cab, they also had to dispatch the train in stations. The experimental operation ended on 8 January 1985, since then the units were used together with the other DT3 under normal conditions.

The cars mainly differed by the square headlights instead of round headlights and a smaller interior in the first cab car of the units as the LZB computers needed more space than available in the cabs. When it came to the refurbishment of many DT3 units in the 1990s the DT3-LZB only received the interior refurbishment and did not get their front replaced as it was unclear for a long time whether the six units would be retired or would remain in service. As a result of the incomplete refurbishment they were the last cars with the old red front since 2002 which has always been prone to rust, making the front window frames leaky over the last years. After the units #922 and #923 were already taken out of service in June 2016, all remaining DT3-LZB cars were retired in December 2016 and scrapped in April 2017 after being cannibalized to get spare parts for the remaining DT3E cars.

Today

In the early 2000s, the DT3E and DT3-LZB were replaced by DT4s on the U1 line and were permanently assigned to the U2 and U3 lines. After 2009, the DT4 unit also replaced the DT3s on the U2 line and they were moved to U3 line where they started to appear on a regular basis at the end of the 1990s. Since 2009 they were also in service on the U1 again, mostly during peak hours but also on regular trips. They are being replaced by the new DT5 since 2013.^[5] Retirement of the remaining trains started in 2015 with the units 802 and 856 being taken permanently out of service (856 was sent into the DT3N refurbishment in early 2017, while 802 - among other cars - was scrapped).^[6]

At the end of April 2017 service of the remaining 44 units has - theoretically - been limited to peak hour services on the U1 and U3, yet there are still a few regular U3 trips being served by DT3E as there are not enough DT5 units available yet for a complete replacement. This is planned to happen from summer 2017 on.^[7] After that also the additional peak hour services on the U3 are going to be slowly converted into DT5 services as soon as there are enough units available for that. From 2019 on it is planned only to run the ten remaining DT3N on U1 peak hour services, with a possible full retirement in 2026. The oldest DT3N (803) would be 58 years old at that point.

One unrefurbished unit (#909) that was taken out of service in 2000 is being preserved for a later use as a museum car. In 2013 it had to be partly cannibalized since it there was no other way to receive spare parts (retiring a DT3E car for that purpose was not an option yet). As soon as its restoration begins the car will be re-completed again, this time by taking parts from retired DT3E cars.

Gallery

References

External links

• Description of the type DT3 on hochbahnbuch.de - German

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