Karnaphuli Tunnel: A Gateway to Progress and Connectivity

Overview

The Karnaphuli Tunnel is an underwater expressway tunnel beneath the Karnaphuli River in Chittagong, Bangladesh — the first tunnel of its kind in South Asia. It links South Patenga, on the city side of the river, with Anwara on the southern bank, giving Bangladesh's principal port city a fixed crossing downstream of its existing bridges. The tunnel itself is 3.32 kilometres long, and the full route, including approach roads and a viaduct, runs to 9.39 kilometres.

The tunnel was inaugurated on 28 October 2023 by then prime minister Sheikh Hasina, under the name Bangabandhu Sheikh Mujibur Rahman Tunnel, and opened to traffic the following morning. In February 2025, the interim government renamed it the Karnaphuli Tunnel. Built by a Chinese contractor with a large Chinese loan, it was conceived as the centrepiece of a plan to grow Chittagong on a "one city, two towns" model across the river. Since opening, however, it has carried only a fraction of its projected traffic, and its toll income covers barely half — at first barely a quarter — of what it costs to run, making it one of the most debated infrastructure projects in the country.

Location and Design

The tunnel passes under the Karnaphuli River at the southern edge of Chittagong, close to the river's mouth. Its western portal is at South Patenga, near the airport and the Patenga waterfront; its eastern portal is in Anwara Upazila, on the road towards Cox's Bazar. Before the tunnel, traffic between the city and the southern bank crossed the river well upstream, at the Shah Amanat Bridge, or not at all — the river effectively cut the port city off from its own southern hinterland.

The crossing consists of two parallel tubes, each carrying two lanes of traffic in one direction, for four lanes in total. Each tube is 10.80 metres in diameter, and the tubes lie between 18 and 31 metres beneath the river. The maximum operating speed is 80 km/h. The tunnel is monitored by more than 100 closed-circuit cameras capable of reading vehicle licence plates, and its precast tunnel segments were manufactured in Zhenjiang, China, and shipped to the site. The project was implemented by the Bangladesh Bridge Authority (BBA) and built by the China Communications Construction Company (CCCC), the Chinese state-owned construction group.

Project History and Construction

A fixed crossing under the Karnaphuli had been discussed for years before a traffic survey in 2013 gave the project its founding numbers: the survey projected that 6.3 million vehicles a year — about 17,260 a day — would use the tunnel in its first year of operation, rising steeply thereafter. The Executive Committee of the National Economic Council (ECNEC) approved the project in November 2015 at an initial estimated cost of Tk 8,446.64 crore.

Construction was bound up with Chinese state financing from the start. Prime Minister Sheikh Hasina and Chinese President Xi Jinping laid the project's foundation stone on 14 October 2016, during Xi's state visit to Dhaka, and the construction site was formally inaugurated a year later, on 14 October 2017. On 24 February 2019 Hasina inaugurated the tunnel-boring phase, after which the two tubes were driven beneath the riverbed. By 26 November 2022, when the prime minister attended an event marking the completion of the south tube's general work, the north tube was reported to be 99 percent complete. The project, like its counterpart at the Padma Bridge, was delivered by the Bangladesh Bridge Authority under the Bridges Division.

Financing and Cost

The tunnel's cost grew substantially between approval and completion. From the Tk 8,446.64 crore approved in 2015, the completion cost was reported at Tk 10,374 crore, and the Implementation Monitoring and Evaluation Division (IMED), in its later completion evaluation, put the total project cost at Tk 10,689.42 crore.

Roughly half the money was borrowed. Under a loan agreement signed in October 2016, the Export-Import Bank of China provided Tk 5,913 crore as a 20-year loan at 2 percent interest; the Government of Bangladesh funded the remainder from its own resources. CCCC's role did not end with construction: the company also holds a five-year contract, worth Tk 983.82 crore, to operate and maintain the tunnel and collect its tolls — a figure that includes about Tk 300 crore for security scanners, leaving net operation and maintenance of about Tk 684 crore over the contract period.

Opening and the Renaming

Sheikh Hasina inaugurated the tunnel on 28 October 2023, naming it the Bangabandhu Sheikh Mujibur Rahman Tunnel, after her father, Bangladesh's founding president. It opened to traffic at 6:00 am on 29 October 2023. The opening was a set-piece of the Awami League government's megaproject programme, presented as proof that Chittagong would grow across its river the way Shanghai grew across the Huangpu.

That political framing did not survive the change of government. After the fall of the Awami League administration in August 2024, the interim government began renaming structures that carried the names of Sheikh Mujibur Rahman and his family. On 26 February 2025, the Bridges Division issued a circular renaming the Bangabandhu Sheikh Mujibur Rahman Tunnel as the Karnaphuli Tunnel — the name the project had carried informally all along. The same circular renamed the Bangabandhu Bridge over the Jamuna as the Jamuna Bridge. Both names took effect immediately, according to the Bridges Division.

Tolls and Operations

Tolls were fixed by a Bridges Division notification of 13 July 2023, ahead of the opening, and are charged one-way across twelve vehicle classes. The schedule runs as follows:

• Car, jeep or pickup: Tk 200
• Microbus: Tk 250
• Bus with up to 31 seats: Tk 300
• Bus with 32 seats or more: Tk 400
• Three-axle bus: Tk 500
• Truck up to 5 tonnes: Tk 400
• Truck of 5 to 8 tonnes: Tk 500
• Truck of 8 to 11 tonnes: Tk 600
• Three-axle truck or trailer: Tk 800
• Four-axle truck or trailer: Tk 1,000, plus Tk 200 for each additional axle

The rates made the tunnel a relatively expensive crossing for the light vehicles that were expected to dominate its traffic, and notably cheaper per crossing than the Padma Bridge — a car pays Tk 200 here against Tk 750 there. In the tunnel's first month of operation, from 29 October 2023, 170,782 vehicles crossed and paid Tk 4.02 crore in tolls — a promising start that later months did not sustain.

Traffic and the Revenue Shortfall

The tunnel's central problem is that the traffic its feasibility studies promised has not arrived. The project documents projected an average of 28,305 vehicles a day by 2025. The reality, recorded by the Bridge Authority, is roughly one-seventh of that: in the tunnel's first year, from 29 October 2023 to 22 October 2024, 1,411,412 vehicles crossed — an average of 3,910 a day — and paid Tk 37.44 crore in tolls. About 76 percent of those vehicles were light vehicles; buses made up about 10 percent and trucks about 12 percent, so the heavy, high-toll traffic the revenue model depended on largely stayed away.

Investigations since then have converged on the same explanations. IMED's evaluation, echoing the Bridge Authority's own reporting, found that the approach roads on both banks were not built for long-distance traffic, so through vehicles find the tunnel route slower than the older crossing; heavy vehicles in particular tend to avoid it, preferring the Shah Amanat Bridge route into the port. The two great traffic generators the forecasts counted on — the Mirsarai economic zone and the Matarbari deep-sea port — were still under construction, and industry on the Anwara bank had not yet grown around the eastern portal. In other words, the tunnel opened years before the network it was designed to serve.

The result is a structural deficit. In the 2023–24 fiscal year, operation and maintenance cost about Tk 174 crore against toll revenue of Tk 28.4 crore — a loss of about Tk 147 crore. In 2024–25 the loss widened to about Tk 189 crore, with costs of about Tk 226 crore against Tk 38.58 crore in tolls, and the Bridge Authority projected a further loss of about Tk 169 crore for 2025–26. By October 2026, a BBA report placed before the parliamentary standing committee on planning recorded 4.172 million vehicles in total since opening — an average of about 3,865 a day. Austerity measures have cut daily running costs from about Tk 37.47 lakh at opening to about Tk 22–23 lakh, but daily toll income, at about Tk 11 lakh, still covers only around half. The Road Transport and Bridges Adviser of the interim government, Muhammad Fouzul Kabir Khan, described the tunnel as more of a "showpiece project" of the previous government than one designed for operational efficiency, and in July 2026 IMED reported financial irregularities of Tk 1,616 crore in the project, with 68 unresolved audit objections, 48 of them classified as serious.

Connectivity and the Chittagong Port Economy

The tunnel's defenders argue that its value cannot be judged on its first years alone. It shortens the road distance between Chittagong and Cox's Bazar by about 40 kilometres, and it sits on the corridor between two of the country's largest future traffic generators: the National Special Economic Zone at Mirsarai, north of the city, and the Matarbari deep-sea port at Maheshkhali, to the south — both still under construction when the tunnel opened. Port-related development on the Anwara bank is also under way: Karnaphuli Dry Dock Limited is building seven jetties there, three already operational, which the Bridge Authority estimates could eventually handle 10–12 million tonnes of cargo a year and add Tk 200–240 crore a year to the tunnel's toll revenue.

The authorities have also moved to fix the tunnel's weakest link — its approach roads, which were never designed for long-distance traffic. ECNEC has approved a Tk 336 crore project to widen the 17-kilometre Anwara–Chandanaish road, so that Cox's Bazar-bound vehicles can use the tunnel without detouring through Patiya. Other measures in the Bridge Authority's plan include leasing out the tunnel's service area, cutting operating costs further, and directing long-distance vehicles through the tunnel rather than through Chittagong city.

Outlook and Conclusion

Three years after opening, the Karnaphuli Tunnel remains an engineering achievement in search of its traffic. It is a technically accomplished work — the first underwater road tunnel in South Asia, driven beneath a working port river and completed without a comparable precedent in the region. But it was justified by traffic forecasts that actual usage has come nowhere near meeting, financed substantially by a Chinese loan whose repayment must be serviced regardless, and it loses money every day it operates.

Its future depends on developments outside the tunnel itself: the completion of the Matarbari deep-sea port and the Mirsarai economic zone, the upgrading of its southern approach roads, and the growth of industry on the Anwara bank of the river. If those arrive, the tunnel may yet become the link its planners intended, joining the two halves of a greater Chittagong. If they do not, it will stand as the clearest cautionary example in Bangladesh's megaproject era of the distance that can open between a feasibility study and the road outside.