Decline, part I (1958-1966)
As the effort needed to acquire modern tramcars appeared to be not feasible and the traffic congestion kept increasing, the STCP had to find more simple ways for modernisation. While the Central Government did favorite electric traction instead of combustion engines, the choice was made for gradually replacing the trams by trolleybuses. Although trolleybuses also came on a few places where never trams had been, e.g. the lower deck of the Ponte D.Luiz I.The first victims of replacement were the lines to VN de Gaia (13 & 14), Lordelo (3) and Campanhã (11 & 12). However line number 3 returned by renumbering of the existing route 4/. Due to extensions of the habour of Leixões and replacement of the bridge crossing this harbour, the lines (1, 5, 16 & 19) to Leça da Palmeira were cut back to Matosinhos. Here a Diesel powered bus took over.
Another measure practiced on a large scale since 1960, was connecting lines at the Praça da Liberdade with each other by through services. The routes of the 1963 network were:
- 1 - Praça da Liberdade - Infante - Alfândega - Massarelos - Foz (Castelo) - Castelo do Queijo - Matosinhos (Cut back to Infante 17 November 1968)
- 1E - Praça da Liberdade - Infante - Alfândega - Massarelos (Closed 17 November 1968)
- 2 & 2/ - Praça da Liberdade - Carmo - Massarelos - Foz (Castelo) - Castelo do Queijo - Fonte da Moura - Boavista - Carvalhosa - Rua Cedofeita (opposite direction Rosario) - Carmo (Number shields were changed en route)
- 3 - Praça da Liberdade - Carmo - Palácio - Boavista - Fonte da Moura - Pereiró (Renumbered from 4/ on 3 November 1960)
- 4 - Praça da Liberdade - Carmo - Rua do Rosário (opposite direction Cedofeita) - Carvalhosa - Boavista - Fonte da Moura - Pereiró
- 5 - Carmo - Rua do Rosário (opposite direction Cedofeita) - Carvalhosa - Boavista - Fonte da Moura - Castelo do Queijo - Matosinhos
- 6 - Praça da Liberdade - Carmo - Rua do Rosário (opposite direction Cedofeita) - Carvalhosa - Carvalhido - Monte dos Burgos
- 6/ - Praça da Liberdade - Carmo - Rua do Rosário (opposite direction Cedofeita) - Carvalhosa - Carvalhido
- 7 - Carmo - Rua das Oliveiras (opposite direction Cedofeita) - Praça da Republica - Arco d'Agua - Amial - São Mamede - Ponte da Pedra
- 7/ - Praça da Liberdade - Carmo - Rua das Oliveiras (opposite direction Cedofeita) - Praça da Republica - Arco d'Agua - Amial (from 1960 this line was linked with line 10E by through services)
- 7// - Batalha - Gonçalo Cristóvão - Praça da Republica - Arco d'Agua - Amial - São Mamede
- 8 - Praça da Liberdade - Carmo - Rua das Oliveiras (opposite direction Cedofeita) - Praça da Republica - Paranhos (from 4 March 1960 until 11 June 1964 linked with line 11 by through services)
- 9 - Praça da Liberdade - Praça Marquês de Pombal - Rua Costa Cabral - Areosa - Águas Santas - Ermesinde (Closed 17 September 1967; from 3 October 1960 until closure linked with line 1 by through services)
- 9/ - Bolhão - Praça Marquês de Pombal - Rua Costa Cabral - Areosa (Closed 17 September 1967)
- 9// - Batalha - Praça Marquês de Pombal - Rua Costa Cabral - Areosa - Águas Santas - Ermesinde (Closed 17 September 1967)
- 10 - Bolhão- Bonfim - São Roque - Venda Nova (Closed 1 January 1967)
- 10/ - Bolhão - Bonfim - São Roque - Santa Eulália - São Pedro da Cova (Closed 1 January 1967)
- 10// - Bolhão- Bonfim - São Roque - Santa Eulália - Gondomar (Closed 1 January 1967)
- 10E - Praça da Liberdade - Bolhão- Bonfim - São Roque (Closed 1966, from 3 October 1960 this line was linked with line 7/)
- 15 - Praça da Liberdade - Batalha - Bonfim - Antas - Rua Costa Cabral - Praça Marquês de Pombal - Praça da Liberdade (One direction only, closed 23 July 1967; from 4 March 1960 until closure linked with line 6 by through services)
- 15/ - Praça da Liberdade - Praça Marquês de Pombal - Rua Costa Cabral - Antas - Bonfim - Bolhão - Praça da Liberdade (One direction only, closed 23 July 1967; from 4 March until 3 October 1960 linked with line 1 by through services and from 3 October 1960 until closure linked with the lines 3 & 4 by through services)
- 15E - Praça da Liberdade - Bolhão - Bonfim - Antas - Rua Costa Cabral - Praça Marquês de Pombal - Praça da Liberdade (One direction only, closed 23 July 1967; from 4 March 1960 until closure linked with line 6/ by through services)
- 16 - Batalha - Gonçalo Cristóvão - Praça da Republica - Boavista - Fonte da Moura - Castelo do Queijo - Matosinhos
- 17 - Batalha - Gonçalo Cristóvão - Praça da Republica - Boavista - Fonte da Moura - Castelo do Queijo - Foz (Castelo)
- 18 & 18// - Praça da Liberdade - Carmo - Massarelos - Foz (Castelo) - Castelo do Queijo - Fonte da Moura - Boavista - Palácio - Carmo (Number shields were changed en route)
- 19 - Praça da Liberdade - Carmo - Palácio - Boavista - Fonte da Moura - Castelo do Queijo - Matosinhos
- 20/ - Praça da Liberdade - Carmo - Palácio - Boavista - Constituição - Rua Alegria - Batalha - Praça da Liberdade; opposite direction line 20 (Closed 21 July 1968)
- 21/ - Praça da Liberdade - Carmo - Rua do Rosário (opposite direction Cedofeita) - Carvalhosa - Boavista - Constituição - Rua Alegria - Batalha - Praça da Liberdade; opposite direction line 21 (Closed 21 July 1968)
