Many vehicles produce smoke in the street, especially in rush hours.
It’s true that in many cities, including Indonesian cities, traffic is heavy early in the morning and late in the afternoon.
Admittedly rush hour can last for more than one hour at a time – in Jakarta it can take 3 hours to get to work and another 3 to get home! However, rush hour is always singular, even if it lasts for 3 hours. Rush hour also begins and ends at predictable times, and so if you say rush hour people know you’re talking about a certain period of time in the morning and a certain period of time in the afternoon:
Many vehicles produce smoke in the street, especially at rush hour. (Maybe 7-9am and 4-6pm, depending on the city!)
There is also some collocation you might want to think about:
And if you do find yourself stuck in rush hour traffic, open up @guruEAP and turn rush hour into study hour!