Highway 40 (Saudi Arabia)

Highway 40 (Arabic: الطريق السريع ٤٠) is a major east–west six-lane controlled-access highway in Saudi Arabia, spanning 1,395 km (867 mi). The highway connects Jeddah, the second-largest city in the kingdom, on the western coast of Saudi Arabia to Dammam, the sixth-largest city on the eastern coast and the largest in the Eastern Province. Apart from Jeddah and Dammam, Highway 40 also runs near or through Mecca, Ta'if, Riyadh, Abqaiq and Khobar along its length, and provides access to the Mahazat as-Sayd and Saja and Umm Al Ramth wildlife sanctuaries.

The highway consists of three traffic lanes and an emergency lane on each side (a total of six traffic lanes and eight total lanes) separated by a median strip. All intersections of the highway are grade separated. The route traverses the mostly flat Najd plateau, and thus requires no bridges or tunnels for most of its length. Near the western part, the highway twists and turns around the Hejaz mountains, before reaching the western coastal plain. Several connector roads and highways connect the highway to other major roads and highways along its length.

In 1953, the need to connect the capital, Riyadh, to the oil-rich economically prosperous regions in the east and the Islamic holy sites to the west arose. The project to build the section of the highway connecting Dammam and Riyadh began construction and was completed earlier than the western section, in 1961. This new road also connected Riyadh to the major agricultural areas in the oasis of al-Ahsa. In 1965, the western section of the highway connecting Riyadh and the Islamic holy sites in the west was completed as the primary east–west axis of the kingdom.

In conjunction with the Kingdom's five-year plans, the Saudi Ministry of Transport prepared its own comprehensive plan, known as the Five-Year Road Programme. The first of these began in 1970 and the system is still implemented today. During the Third Development Plan (1980–85), the Riyadh–Dammam section of the modern-day highway was modernized and measured 375 km (233 mi). Finally, during the Fourth Development Plan (1985–90), the Riyadh–Jeddah section of the highway was modernized and in 1986, the highway was commissioned as Highway 40 in the new, standardised Saudi road network.