Study on potential integration of greenway on urban street canyon at planned residential area of Dhaka city

Abstract

Orchards and meadows featured ancient Dhaka city. Gradually over population has turned it into a concrete jungle. Rapid urbanization replaces foliage with edifices and produces microclimate of higher air temperature or Dry Bulb Temperature (DBT) than rural surroundings. Outdoor temperature of Dhaka is 1-1.5 K higher than that of immediate regions. Thirty percent denizens of Dhaka commute 0-2.5 km on foot daily. Ample striders die in road accident in this pedestrian inimical city. Integrating greenways on the street canyons of Dhaka is an implicit remedy alleviating these delinquents. Tropical studies found that planted urban streets reduce DBT to the extent of 1-3 K. Greenways are linear open spaces built along lush green, stream or similar features for non-motorized users that ameliorate environment. This study concerns about the microclimatic impact of integrated greenways on street canyons at planned residential Dhaka. To unravel this quest, field study was steered at eight potential planted and bare street canyons at planned residential Dhaka. The microclimatic parameters were recorded from 10.00-18.00 hours at summer days using Thermo-Anemometer and Hygro-Thermometer. An existing bare street canyon was simulated from 08.00-20.00 hours using Envi-met. Greenway was integrated on idem bare model and simulated from 08.00-20.00 hours. Simulated maps were extracted through Leonardo. Field and simulation study were analysed to scrutinize the microclimatic impact of integrated greenways on the street canyons of Dhaka. This study reveals that greenways hold an immense cooling effect on street canyon microclimate of planned residential Dhaka enhancing pedestrian thermal comfort. The integrated greenway reduced DBT to the extent of 7.03-10.30 K, Mean Radiant temperature (Tmrt) 5.76-31.36 K and increased Relative Humidity (RH) 7.90-18.47%. This study unveils the role of integrated greenways on street canyons to lessen the outdoor DBT of Dhaka. This study escorts the urbanites towards a hustle and bustle free thermally comfortable relaxed outdoor walking trail through integrated greenway.