🚦 Route Factor, also known as circuity or detour index, measures how much longer a real network route is compared with the ideal straight-line distance. It is a simple but powerful way to evaluate transport network efficiency.

🏙️ In our 2022 study, we applied Route Factor analysis to Tehran’s 22 municipal districts. The results show that Tehran’s average Route Factor is 1.52, placing the city at an average accessibility level. About 38% of inter-district connections had good or very good accessibility, 32% were average, and 30% were poor or very poor.

🌍 International comparison adds an important perspective. Similar approaches have been used in Paris, London, US metropolitan areas, and large European city samples under the terms circuity, detour index, or network directness. A recent European study reports an average road circuity of about 1.34 across 300 European cities, while London metropolitan regions show values ranging from 1.39 to 2.09.

🔎 Tehran’s challenge is not only the geometry of the street network. Weak land-use mixing, peripheral low-density growth, mountainous or dead-end road patterns, and dependence on private cars all increase real travel distances. As trips become longer and less direct, fuel consumption, congestion, and air pollution also rise.

🎯 This means Route Factor should not be treated only as a transport indicator. It can become a planning tool for identifying where land-use reform, public transport investment, local service hubs, and cleaner mobility interventions are most urgently needed.

❓ Can route-factor analysis help rapidly growing megacities design cleaner, fairer, and more accessible transport networks? I welcome discussion and collaboration from researchers and practitioners working on accessibility, GIS, transport planning, land use, and urban sustainability.