Social and Cultural Impact Assessment of the Dogaz Highway Construction in Tehran

Introduction
This study aims to predict and assess the social and cultural consequences arising from the construction and completion of the "Dogaz" highway in the Tehran metropolitan area. As one of the most critical north–south corridors in the western part of the capital, this project connects key east–west axes—including Shahid Kharrazi, Shahid Hamedani, the Tehran–Karj Freeway, Shahid Lashgari (Karaj Special Road), and Fath highways—thereby playing a pivotal role in completing the regional transport network and alleviating traffic congestion in western and southern districts. Given the supra regional character of this developmental intervention, the study examines its impacts at three spatial levels: the direct intervention zone (extending 3.5 km), the immediate vicinity (Districts 22 and 21, with emphasis on residential complexes such as Kharrazi, Negin e Gharb, and Ghazali Township, as well as scientific research centres), and the broader regional sphere. Adopting a forward looking perspective for the post implementation period (T+1), the research seeks not only to identify positive and negative effects but also to outline plausible scenarios for optimal consequence management.
The theoretical framework draws upon both critical and supportive stances regarding urban highway development. On the one hand, scholars such as Jacobs (1961), Mumford (1958), and Downs (1970) emphasise social fragmentation, diminished neighbourhood quality of life, urban fabric degradation, and adverse environmental impacts. On the other hand, urban planners, economists, and transport engineers regard highways as instruments for facilitating economic growth, rehabilitating decayed urban fabrics, fostering redevelopment in declining neighbourhoods, and responding to the imperatives of modern urban life. In recent decades, movements such as New Urbanism, Smart Growth, and Transit Oriented Development have posed serious challenges to car centric and sprawling urban patterns. The research operationalises a conceptual model based on the "individual–environment–local community" triad and a three fold change framework—namely, alterations in connectivity networks and travel behaviour, shifts in socio economic infrastructure and public services, and transformations in recreational and environmental opportunities—to identify project sensitive variables. A systematic review of empirical precedents indicates that positive outcomes of analogous projects include enhanced safety, traffic reduction, time savings, neighbourhood renewal, and improved urban scenery, whereas negative consequences predominantly involve social disintegration, weakened neighbourly relations, increased noise pollution, loss of place identity, and diminished security in undefended urban spaces.
 
Methodology
This research adopts a mixed-methods design, comprising two sequential phases. In the first phase, thematic analysis with purposive sampling was employed, involving semi structured interviews with 30 municipal executives, senior experts from Districts 22 and 21, university professors, and urban planning specialists, in order to extract the qualitative dimensions and core themes of the project's impacts. The open, axial, and selective coding process yielded 8 main themes and 24 sub themes. In the second phase, a survey method was utilised to collect the views of 60 experts and officials associated with the project through a census approach. Data were gathered using a researcher developed questionnaire. Quantitative data analysis applied descriptive statistics (means, frequencies, percentages) and inferential statistics (one sample t tests). Additionally, scenario planning with cross impact analysis was employed to project consequences for the post implementation period (T+1).
 
Findings
Findings unequivocally demonstrate that the Dogaz highway construction, as a developmental initiative, entails minimal negative consequences and predominantly positive effects. According to the prioritisation performed, the most significant positive impacts, characterised by high intensity and long term duration, include: reduced vehicle fuel consumption (mean = 3.9 out of 5, with 56% of respondents rating it as "high" and 22% as "very high"), decreased expropriation and compensation costs for affected parties (mean = 3.2), shortened travel time and distance (mean = 4.0, with 45% "high" and 33% "very high"), reorganisation of abandoned and derelict lands around the Vardavard River (44% "high" and "very high"), reduced traffic load on Shahid Ardastani Boulevard (67% "high" and 11% "very high"), improved distribution of access to major roadways in Districts 22 and 21 (75% "high" and "very high"), increased driver satisfaction (63% "high"), decreased traffic volume at the Fath–Dogaz intersection (70% "high" and "very high"), facilitated access to Kharrazi, Mehsan, and Moallem residential complexes, and enhanced safety with reduced financial and human losses on Ardastani Boulevard (50% "high" and "very high").
Conversely, the most critical negative impacts, with high intensity and medium  to short term horizons, comprise: restricted traveller access to Hazrat Khadijeh (PBUH) Park via the Karaj Special Road (east west direction; mean = 3.4), poor visual quality and landscape disorder in successive views along the Vardavard river valley (50% "high" and "very high"), increased noise pollution for adjacent residential complexes (20% "high"), reduced residential comfort due to elevated vehicular traffic (30% "high"), and visual clutter along the watercourse margins caused by extensive barren and abandoned military lands (44% "low" and 33% "moderate"). The results further indicate that consequences such as neighbourhood level social fragmentation (67% "not at all" and "low"), decreased use of public transport (68% "not at all" and "low"), proliferation of undefended urban spaces (50% "not at all" and "low"), diminished social security (45% "not at all" and "low"), loss of the natural landscape of the Vardavard river valley (40% "not at all" and "low"), and reinforcement of local identity (50% "low") are among the least likely to occur, suggesting that the project contributes positively to reducing social harms and avoiding disruption to neighbourhood cohesion.
Scenario analysis outlines three distinct prospects for the project's future. The first scenario (optimistic) emphasises the development and completion of the highway network as a means to facilitate intra  and inter urban traffic, forecasting benefits such as an integrated western Tehran transport grid, reduced dependence on the Karaj Special Road monopoly, enhanced tourism and commercial potential in Districts 21 and 22, decreased accidents and fuel consumption, redistribution of traffic loads across east–west corridors, lower social vulnerabilities, and increased utilisation of District 22's travel attractions. The second scenario (pessimistic) warns that, owing to the phenomena of "induced travel demand" and "funnelling into a bottleneck," the highway may not only fail to reduce congestion but, by shifting traffic from one point to another, may actually exacerbate gridlock, encourage private car usage, and ultimately lead to project failure—as observed in the case of the Sadr elevated expressway. The third scenario (realistic) advocates for traffic equilibrium through simultaneous public transport development, proposing measures such as travel demand management, expansion of metro lines along east–west axes, door to door transport systems, at grade light rail for satellite towns, highway tolling, and promotion of a public transport culture.
 
Discussion and Conclusion
In conclusion, the research asserts that a "traffic management" approach must replace the traditional "traffic facilitation" paradigm. Experiences from various highway development projects in Tehran demonstrate that merely responding to travel demand by building more highways does not reduce congestion; rather, owing to multiple traffic nodes and incomplete connections, it results in traffic backlogs and extended queues. Hence, instead of focusing solely on smoothing traffic flow, policies of travel demand management—including congestion pricing, public transport incentives, secured local access, east–west linkage of the highway (via Abshar, Niaiesh, and Abshenasan Boulevards), and continuous traffic load monitoring—should be prioritised. The proposed mitigation and monitoring system comprises 12 operational measures, such as demand management during holidays and peak hours, regulating heavy vehicle access, securing access to the Mehsan and Moallem residential complex, pursuing the S20 Boulevard project, adjusting the slope of Shahid Ardastani Street to prevent cold season and rainy weather accidents, improving access to the Shahid Kharrazi residential complex, establishing a safe access hierarchy to Hazrat Khadijeh (PBUH)
Park, and providing appropriate ramps at key interchanges. Furthermore, given the extensive residential, commercial, scientific, and medical developments projected for District 22 in the coming years, the need for broader measures in public transport expansion and regional traffic management becomes ever more pressing.