Climatic damages of pedestrian bridges over Tehran Metro-police

Pedestrian bridges are among the factors that contribute to the soft traffic on the streets and express-ways of big cities. The purpose of this study was the monitoring and review of damages in foot-bridges and their vulnerabilities for pedestrians over the throughput of Tehran as a vast city. It was determined 710 pedestrian bridges over Tehran metro-police based on google-earth images. When this area was divided equal units based a geographical grid, the frequency of bridges decreased to 62 ones as the frequency of selected bridges (SB). It means one SB from every unit. The information of SBs was gathered by designed and verified questionnaires through several field visits. We designed final patterns based on combine of SB information and the atmospheric data of weather stations including monthly temperature, precipitation, and relative humidity over Tehran and its suburb. The patterns revealed that the slipperiness of the bridge for the pedestrians, trunk oxidation, and bridge connection oxidation increase from the south to the north of Tehran. Similarly, relative humidity increases from the south to the northwest of Tehran. Meanwhile, damages to electricity wires and cables and damages to the floor asphalt, which are observed more in the center and northeast of Tehran, have been less consistent. The pattern of "synergy of all damages to Tehran pedestrian bridges" indicated that most of the damages have occurred in the urban districts 1, 2, and 4 of Tehran. All in all, the findings of this study and other related national and international research projects showed that pedestrian bridge structure is not congruent with the hot and dry climate in the south and the temperate and semi-arid one in the north of Tehran, but the underpass structure is more congruent, less costly, and socially and culturally more flexible.