The Tehran-Shomal Freeway is the largest road construction project in Iran, connecting the capital, Tehran, to the northern region of the country.

The Tehran-Shomal Freeway, Iran's largest road construction project, connects Tehran to Chalus. This freeway is a segment of the North-South Trans-Iranian Freeway, providing the shortest route between the Caspian Sea and the Persian Gulf, and plays a major role in regional transit. The freeway route begins at the interchange of Shahid Hemmat Expressway and Azadegan Expressway in Tehran and ultimately connects to the Chalus-Tonekabon bypass in the north via another interchange. To expedite its operational readiness, the 126-kilometer Tehran-North Freeway was divided into four operational sections. This division, in combination with the existing road network, helps to alleviate some of the traffic and transit issues.