More details on the project have emerged in recent days.

Uzbek Deputy Transportation Minister Jasurbek Choriev, in an interview broadcast on Uzbek television, described the trans-Afghan project the country’s “second most strategically important” infrastructure project behind the China-Kyrgyzstan-Uzbekistan Railway, which broke ground last year.

The project will cost $4.6 billion and could take about 5 years to complete, he said.

Earlier this year, the Uzbek Transportation Ministry said construction would start this year.

When complete, the project could cut transit times from Pakistan from 35 days to about four and increase trade flows from 300,000 tons currently taken by truck across Afghanistan to 3 million tons initially, according to Choriev. Between 2035 and 2040 that total could rise to 15 to 20 million tons, he added.

Choriev said the framework agreement provides for joint engineering and economic feasibility studies for the project, “a first and a very important step.”

“We’ve long strived and prepared for this. The framework agreement will give all sides the opportunity to take practical steps,” he added.

The deputy minister also acknowledged the challenges the project faces, starting with geography. The line will traverse rugged terrain and require the construction of more than 300 bridges and five tunnels – “and they’re long tunnels,” Choriev said.

Security too remains a concern in both Afghanistan and Pakistan, but Choriev said Afghanistan’s Taliban leadership has provided security guarantees.

The ministers of transport and infrastructure of the three countries signed the framework agreement at a ceremony in Kabul on July 17, representing another boost in warming relations between Afghanistan and Uzbekistan.

For instance, Mirziyoyev met for talks with Afghan Deputy Prime Minister for Economic Affairs Abdul Ghani Baradar on the sidelines of a summit in Azerbaijan in early July, according to Kun, an Uzbek outlet.  And, the two countries signed an agreement on the joint management of the Amu Darya River in late April, the Uzbek outlet Anhor reported.

Financing for the Afghan rail project is another hurdle, and the three countries hope to rely on a mix funding from national, international and private sources. “We’ve already started to receive reactions, started to receive comments, telephone calls. Interest is already being shown,” Choriev said.

Russia strongly backs the project, hoping to expand its own north-south trade network, which the Kremlin sees as a counterweight to US, European and Chinese efforts to build up the Middle Corridor. Russia and Uzbekistan signed an agreement on April 8 to work together on the initial stages of the project, the Russian news agency TASS reported.

Russia became the first country in the world to recognize the Taliban government in Afghanistan on July 4. Despite growing diplomatic relations, the Uzbeks have indicated they are not quite ready, Kun reported in early June.

There are other rail projects in the works for Afghanistan. A different trans-Afghan corridor would run from the Turkmen border and eventually to the Pakistani coast. The Turkmen and Kazakh governments are pushing that route, with the later having committed $500 million to build that line as far as Herat, Kursiv, a Kazakh outlet, reported in April. Iran is already building a line from its border to Herat.