List of Africa’s Longest Tunnels: The Top 6

Africa continues to push the bounds of its construction capabilities, especially regarding Africa’s longest tunnels. These tunnels are used for various purposes across the continent, some are waterways, others are railway tunnels, and even road tunnels. Drilling tunnels is quite hard and even harder when both sides of drilling have to meet by maintaining a line of sight. This is because one cannot use a compass since there are no magnetic fields or even GPS to guide their work. Engineers and other construction workers have to endure challenges to ensure the delivery of these tunnels. This list appreciates their efforts and commitment as it takes a keen insight into Africa’s top six longest tunnels.

1. The Gautrain Line Tunnel- South Africa (15.5km)

Currently, Africa’s longest tunnel, the Gautrain rail tunnel is considered one of the railway construction marvels in Africa. It is the first of its kind in Africa in terms of rail transport. The section of the railway line has a 15.5km long tunnel that passes underground. It stretches from Malboro to Park Station in Johannesburg. The design of the railway tunnel includes seven emergency shafts for access by emergency services personnel. Of the seven, five of them are deeper than 52 meters and have refuge shelters incorporated into them. It includes three underground stations: Johannesburg Park Station, Rosebank Station, and Sandton Station.

2. Hex River Tunnels- South Africa (13.5km)

The fourth tunnel of the Hex River Tunnels is considered the second longest tunnel. It was the longest single railway tunnel in Africa before the Gautrain Line tunnel eclipsed it. The tunnel is on the Hexton railway route between De Doornas and Kleinstraat through the Hex River mountains. This Hex River tunnel connects De Doorns in the Hex River valley with Tows River in the Great Karoo. Furthermore, it is part of the main rail route between Cape Town and Johannesburg. Operation of the tunnel system commenced in April,. 1989, more than forty years after the first portals were sunk. It was officially opened for use on 27^th November 1989. Tunnel 4 was the longest railway tunnel in Africa until 2009.

3. El Affroun – Khemis Miliana line- Algeria (7.4km)

Part of the Algiers-Oran railway system, the El Affroun-Khemis Mililana line is North Africa’s longest tunnel. It It is also the longest bilane railway tunnel in Africa and among the longest railway tunnels in Africa. The Algiers-Oran Railway is one of the major components of the Algerian railway network. It links Algiers station with Oran. Stretching to a length of 7.34 kilometers, the twin-bore tunnel is the centerpiece of the 56 kilometers El-Affroun-Khemis Mililana line. The completion of this tunnel is significant as it reduced the journey time between the capital of Algiers and the city of Oran.

4. Ngong SGR Tunnel- Kenya (4.1km)

Occupying the fourth spot on the longest tunnels is the Ngong SGR tunnel in Kenya, East Africa. Considered East Africa’s longest tunnel, the Ngong SGR tunnel is 4.1km long. It is also the entry point to the floor of the Great Rift Valley from the Standard Gauge Railway’s terminus in Nairobi. This is until the border town between Kenya and Uganda. The construction of the tunnel was necessitated as there was no other way to access the floor of the valley. Based on the location of the Ngong area, it was considered ideal to design the tunnel there as it is part of the escarpments. It would also directly place the railway line to the floor of the Great Rift Valley. The Ngong SGR tunnel posed arduous challenges for the engineers involved such as the drilling of the bedrock, but eventually prevailed.

5. Huguenot Tunnel- South Africa (4km)

Located in South Africa, Cape Town, the Huguenot Tunnel is among South Africa’s longest tunnels. It is also one of the longest road tunnels in Africa with a distance of 3,913 meters. Furthermore, it is the fifth when ranking Africa’s longest tunnels. The Huguenot tunnel pass was constructed between 184 and 1988 at around $130M at the time. An awe-inspiringly beautiful, high-altitude viaduct bridge leads up to the Huguenot Tunnel from its south side. The construction of the 4 km-long tunnel was significant as it drastically reduced the distance of the old pass by 11 kilometers. The tunnel is a two-way carriage tunnel. It extends the N1 through the Du Toitskloof mountains that separate Paarl from Worcester.

6. Al Mowahidin Tunnel- Morocco (2.1km)

Capping off the longest tunnels in Africa in the sixth spot is the Al Mowahidin tunnel in Morocco, Casablanca. The Al Mowahidin tunnel is considered one of the longest tunnels in Africa. It is also Africa’s second road tunnel at 2,179 kilometers including 1,817 kilometers underground. The scope of construction of the tunnel entailed the construction of a road tunnel lowering every crossroads. This includes along boulevards of the Almohades, Sidi Med Ben Abdellah et Zaid ou Hmed, and leading to FAR Avenue. The tunnel was officially opened by various dignitaries in the Moroccan government in July 2021. The officiating committee included Said Amidoch, the governor of Casablanca-setate region.