The city council or other governing body of each city in the State of Alabama having according to the most recent federal census a population of more than 35,000 inhabitants shall have full power and authority to require railroad companies to construct and maintain within the city limits viaducts, bridges, and tunnels or parts of viaducts, bridges, and tunnels and their approaches over, along, or under the tracks at their own expense, such bridges and their approaches, tunnels or other conveniences at public crossings and such viaducts and their approaches over their tracks where the same cross or extend along public highways or streets.