Theodorus Engelbertus "Tjerk" Westerterp (2 December 1930 – 7 October 2023) was a Dutch politician and diplomat of the defunct Catholic People's Party (KVP) now merged into the Christian Democratic Appeal (CDA) party and businessman.[1]
Following the second cabinet formation of 1972 Westerterp was appointed Minister of Transport and Water Management in the Den Uyl cabinet, taking office on 11 May 1973. He took many measures that had a lasting positive impact on traffic safety in the Netherlands, like making seat belts and the moped helmet mandatory. He was also responsible for the decision to build the Eastern Scheldt storm surge barrier. The cabinet fell on 22 March 1977 after four years of tensions in the coalition and continued to serve in a demissionary capacity.
After the election of 1977 Westerterp again returned as a Member of the House of Representatives, taking office on 8 June 1977 but because of the dualism customs he resigned his seat in the House of Representatives on 8 September 1977. Following the cabinet formation of 1977, the Den Uyl cabinet was replaced by the Van Agt–Wiegel cabinet on 19 December 1977, and Westerterp was not given a cabinet post in the new cabinet and he subsequently returned to the House of Representatives following the appointment of Til Gardeniers-Berendsen as Minister of Culture, Recreation and Social Work in the new cabinet, taking office on 22 December 1977 serving as a backbencher.
In January 1978, Westerterp was nominated as Chief executive officer (CEO) and Chairman of the Board of directors of the Amsterdam Stock Exchange, he resigned as a Member of the House of Representatives the same day he was installed as CEO and Chairman on 15 February 1978. As CEO of the Amsterdam Stock Exchange he came up with the idea of the AEX index.