Possible benefits from greening of public transport stops in Sofia, Bulgaria

Public transport shelters provide an unused surface that can be utilized in various ways, including for unconventional landscaping. The benefits from greening of public transport shelters are insufficiently studied and unutilized. The article evaluates some of the benefits which may result from the construction of green public transport shelters in the central part of Sofia. There are a total of 2780 aboveground public transport stops in Sofia. In the surveyed area are located 257 stops, 150 of which currently have shelters. The potential of greened shelters to remove PM10 and CO2 from the ambient air is estimated for several different scenarios. If 250 public transport shelters are entirely greened (roof and 3 walls) with Festuca sp., the removed PM10 will be about 20 kg/yr, or 0.01% of the yearly emissions of PM10 from transport in the surveyed area. The sequestered CO2 will be 17047.3 kg /yr., or approximately the CO2 emitted by 40 diesel cars with an average daily mileage of 10 km per day for a year. The reduction of PM10 and CO2 is not significant, however, in a big city with intensive construction and a constantly increasing population, every possibility for greening needs to be explored. Green stops may be used in combination with other measures. Proper selection of plant species and design solutions maximizing the green surface will increase the benefits.