The proposed new routes for Istanbul’s third bridge across the Bosphorus does not only threaten the ecology of the city, but it will give a way to new areas for unplanned urbanization.
There are only two bridges in the world which connect continents. Both happen to be in Istanbul. Running across the Bosphorus and connecting Asia and Europe, Istanbul’s bridges have always spurred hot debates before they were built. The opening of each bridge also brought with itself cogitation of building a new bridge. Actually each bridge built on the Bosphorus was a messenger of a new bridge and the discussions around it. Surprisingly, the construction of the second bridge (Fatih Sultan Mehmet Bridge) was realized only 15 years after the opening of the first Bosphorus bridge; in 1973. Moreover, five years following the introduction of second bridge, debates regarding a third bridge started along with active planning. Although the project has been included in the numerous national investment programs, a number of organized reactions and protests put a halt to the evolution of the project. Thus no progress was recorded until recently. The debates have been revitalized as the AKP leadership proposed new routes, moving the bridges construction to the north-most boundaries of Istanbul.
The threats of the highways on the ecological system
For years, the sustainability of the entire natural-ecological areas in the north of Istanbul has been under severe threat due to factors such as migration, insufficient infrastructure, delayed plans and related implementations, as agricultural land was taken over by industry and urbanization. The increase in the trends of owning a dwelling place in the suburbs and erroneous forest land ownership policies (a.k.a. 2B) among many. The dimensions of this threat are asserted by the urban sprawl especially after the construction of the second bridge and the Trans European Motorway (TEM) connections. The third bridge, which is planned to be erected on the North boundaries of Istanbul, threatens the only natural areas left in the city. These ecological areas at the north of the city will deeply be influenced by the urban sprawl and eventually the city residential areas will shift to North Sea shoreline. Thus the occurrence will impose the following irreversible effects on the natural environment of Istanbul.
- After the opening of the third bridge and the related highways, significant new traffic will be generated. The traffic will increase the emissions and trigger the construction of new roads and buildings that will step up the heat island effect on Istanbul. While this effect has already started to be experienced by recorded temperatures above the seasonal averages and low water level of the dams recently, both urban and rural preservation strategies must be developed to maintain the water quality of the basins and the integrity of the forests by planning designated open-air spaces.
- A significant portion of the approach roads of the 3rd bridge will lay along important drinking water reservoirs of Istanbul. The related areas are expected to be exposed to residential pressure. Although the population settled around Omerli basin from 1935 and 1975 tripled, when the connecting highways of the second bridge beacame after 1990 its population exploded to a figure close to 600,000 with a 50 times increase. This specific situation clearly exhibits the residential pressures on the vital basins of Istanbul.
- Main and secondary arterials connecting the route of the 3rd bridge will adversely affect the forests in the north and the wildlife around these forests. Especially, the highways with safety barriers put physical obstacles for the strolling and break-up the living areas of wild animals while limiting the dispersion areas of them at the north of Istanbul.
- The trees cut down will reduce the effectiveness of the forests in soaking up the poisonous carbon gases and the efficiency of the forests will significantly decrease. Moreover, new highways traversing through forests will bring a great risk of fire, as well. Besides, just like the case for all highways, the pollutants emitted by the motor vehicles present a threat for the environment.
- Along the 5 km long impact belt of the proposed route of the 3rd bridge and its approach roads, 34% of the private forests, 46% of the forest areas, 38% of the 2B areas and 43% of the agricultural areas are present). This impact belt also covers 18% of the absolute protection zone of the water basins that has a strict ban on settlements except purification facilities. In the meantime, a total 29,000 hectares of natural protection zone (45% of the entire protection zones) are under the risk of destruction. Inside the proposed expropriation area of 150 m, lie 680 hectares of natural protection zone, 931 hectares of agricultural area, more 2.5 million trees and 1453 hectares of forest areas that will be directly affected and entirely demolished because of being on the route of the new highways.
New Ecological Additions to the Existing Problems of the City
Today the city has to cope with many problems related with the migration which in many cases is accepted as the natural result of the formation of the new bridges. Unplanned urbanization, diminishing of the water resources, the social polarization of the rich and poor neighborhoods, the lack of the healthy urban planning decisions and gentrification of land users in urban renewal projects are but a few of the problems the city is facing today.
The experiences of the first two bridges show that the last remaining natural living areas of the city and the ecological balance in these areas will be subject to a permanent transformation after the construction of the third bridge. The map of Istanbul prepared by a natural structure analysis which depicts tolerance thresholds against the physical impacts presents only one of the objections against the forming of a new bridge and its false land-use decisions.
As the UCTEA Chamber of Urban Planners Istanbul Branch we believe the policies that cover the above mentioned problems should endogenously include the transportation solutions while referring to public transport oriented solutions that watch out for the balance between the city’s ecological/natural integrity and the settlements. In this context, we offer railway based implementations that correct the imbalance of employment and population between sides of Bosphorus without building new bridges.