Crossover bridge

Crossover bridges were components of Cardassian space stations such as Deep Space 9. The bridges connected the central core of the station to the habitat ring, and further to the docking ring and its associated pylons. (Star Trek: Deep Space Nine)

According to the master systems display used by Starfleet, bridges that connected the central core with the docking ring were designated primary crossovers; those that extended to the habitat ring alone were secondary crossovers. 

In 2369, Lieutenant Jadzia Dax scanned the crossover bridges in order to detect the source of graviton pulses threatening the station. 

Later that year, Odo instructed Chief Miles O'Brien and Commander Benjamin Sisko to take crossover bridge one to reach the cargo bay which led to docking port four. 

In 2370, O'Brien was on his way to crossover bridge three when he encountered graffiti in the shape of the symbol of The Circle. 

Background information
The Star Trek: Deep Space Nine Technical Manual describes the bridges as being constructed of 26% kelindide, 70% rodinium, and 4% toranium, the same composition as the docking pylons.

The script of uses the term 'crossover "bridges"' to describe the walkways on the upper level of the Promenade which lead to the outer viewing area; however, this term is not used to describe those locations in-universe.