to the attitudes in those years - obstructed car traffic on the main roads. The realisation that the contemplated abolition of the tramway would not be a short-term project, mainly because of the rather lengthy construction of the planned U-Bahn network, led to the introduction, from 1959, of the six-axle articulated type E and E1 trams, of which a total of 427 were built to 1976. This was a generational change of long-term effect. The last high-floor articulated trams to enter the fleet were the Type E2 vehicles, which were built under licence from Duewag, together with matching type c5 trailer cars; they entered service on 28 August 1978 on Line 6, and remain in service today. This type was the first to be fitted with exits featuring retractable steps to improve comfort when entering and alighting. Additionally, the tramcar design was modernized, and the safety features of the technical equipment were considerably improved. A total 98 cars of this type were produced by Simmering-Graz-Pauker, and 24 by Bombardier. The construction of the Vienna U-Bahn led to further extensive line closures in the tramway network, due to a policy that trams are not to operate in parallel with the U-Bahn, even on short sections. As this policy is still in effect today, further closures of tramway lines can be expected, to coincide with the further expansion of the U-Bahn network. However, the continued existence of the tramway network in Vienna is no longer in question, and there are even some new openings planned. For reasons of economy, Wiener Linien ceased to roster conductors in trailer cars from 1964, and in powered cars from 1972. Industrial relations factors delayed the final departure of conductors until 1996, when the last conductor ended his service (on Line 46). On 2 September 2017 the U1 extension to Oberlaa (former tram 67) opened with great fanfare and the section of tram line 67 from Per-Albin-Hansson-Siedlung was cut to terminate at Reumannplatz. Also, a new network of bus services in the Favoriten area commenced. From the same date tram lines 2, 10, 44 and 60 saw major changes and Line 58 was replaced by extensions of lines 10 and 60. Lines , these lines operated: The longest line is currently line 11, running from Otto-Probst-Platz near the Wienerberg via the districts of Favoriten and Simmering to Kaiserebersdorf. On the other hand, line 42 is the shortest