Waze could have an algorithm to detect where are the semaphores in the city, and keep how long they take to open, to avoid the semaphores that take longer.
There are some semaphores in São Paulo that take too long to open. It would be very useful to avoid them.
Tiago Maduro Dias commented
In principle Waze should work around this by taking into account the average car speed on every road stretch. As long as enough people use the service, this information should reflect the existence of semaphores and how long they take to open.