In the bottom it says: With stories from reporters Alessandra Freitas and Pedro Tavares. I selected and translated the one I wrote. 

Mysteries of the city

Crosswalking

Implemented in the 1970s, the 9500 traffic light control buttons were implemented to reduce pedestrian waiting time. In some places, however, they make little difference, as shown in the test below performed by VEJA SÃO PAULO. According to the Traffic Engineering Company (CET), the device does not influence the opening cycle at peak times in busy regions. On the other hand, there are signs that only close if the button is pressed, as in points of the General Olímpio da Silveira, Ipiranga and São João avenues.

Brigadeiro Faria Lima avenue, 1134, Pinheiros
Normal opening time of the traffic light: one minute 33 seconds
If you push the button: eleven seconds less

Boa Vista street, 51, center
Normal opening time of the traffic light: 31 seconds
If you push the button: two seconds less

Heitor Penteado street, 1230, Sumarezinho
Normal opening time of the traffic light: one minute 37 seconds
If you push the button: twenty seconds less

Líbero Badaró street, 561, center
Normal time to open the traffic light: one minute and thirty seconds
If you push the button: no difference