Some 750 kilometres (466 miles) long, the $4 billion line connects landlocked Ethiopia to the Red Sea coast in Djibouti.
This could transform how goods and people move, and the increased number of lines is expected to boost trade in countries like Kenya, says Kuria Muchiru, advisory partner, East Africa, at PwC in Kenya
"Because we probably have about 4,000 trucks everyday making the trip up from Mombasa into Nairobi, and some go farther on," adds Muchiru.
The ports are where the magic happens, with 90% of African imports and exports
conducted by sea which can be an issue for trade coming into landlocked countries.
"The new lines will have access to the ports and be able to almost offload directly onto the train and then straight onto inland locations," Muchiru says.
Billions in loans
The new lines are part of the so-called LAPPSET
rail project and the EAC Rail Sector Enhancement Project, also called the East African Railway Masterplan, and managed by the East Africa Community (EAC)
-- an intergovernmental organization run by Burundi, Kenya, Rwanda, South Sudan, Tanzania, and Uganda -- together with consulting company CPCS
But railways don't come cheap, and African countries are borrowing heavily from China to scrape the funds together.
In the 10-year period between 2004 and 2014, African countries borrowed nearly $10 billion for railway projects from China, facilitated by the China Export Import Bank (Exim), according to researchers by SAIS China Africa Research Initiative at Johns Hopkins School of Advanced International Studies (SAIS-CARI).
Why does China invest so enthusiastically?
China sees the railways as an investment opportunity which also creates an export market for their booming steel and construction industries, says Deborah Brautigam, professor of international political economy and director of SAIS-CARI.
"They have overcapacity in China. They have steel that they want to use. They've got experienced companies that know how to build railways."
But it's not without risks, and whether the loans will be fully repaid remains to be seen, she adds.
"That's still a question mark."
However, while countries often dream big, not all projects make it past the planning stage, according to Brautigam.
Looking at larger projects, five railways have materialized so far, with the Tazara railway -- which links Tanzania and Zambia -- being the first to be completed back in the 1970s.
The other four projects are in Ethiopia, Nigeria, Kenya and Sudan, says Brautigam.
The West not as keen
The US and other Western countries have financed some railways and other infrastructure projects across the continent, but they haven't been as keen to invest as China, partly due to a fear that the African countries won't keep up the maintenance, Brautigam says.
"[They] have put some money into these railways but not very much. They really haven't wanted to finance them."
"They felt, and probably rightly, that these governments were not doing a good job with what they had already," she adds.
So are these new East African railway projects feasible? Andrew Grantham, editor at Railway Gazette International who covers railway developments in the area, says that as long as there are funds and political will, there are no technical hurdles to expect.
"The Chinese have built a railway to Tibet, and once you've done that, very few things are going to be a technical challenge."
"If you have the right environments, there is no reason these schemes shouldn't happen," he adds.
While the old colonial lines vary in size and style, the new Chinese railways will be standardized, which makes it easier to link lines and countries, Grantham explains.
"Essentially, the Chinese will give you a catalogue. You pick one and build it."
Is China building everything in Africa?
It's not just railways. The Chinese are involved in constructing buildings, dams, and bridges within the continent.
"Fifty billion dollars a year of construction work is being done by Chinese companies in Africa. There's a huge range," Brautigam says.
Between 2000 and 2011, the Chinese backed more than 1,700 projects
in 50 African countries at a cost of $75 billion, according to AidData.
The Chinese projects are not without controversy, however. Conservationists, for example, have voiced concern
that they could disturb wildlife, as they cut through Kenya's national parks.
China has also been criticized for working with undemocratic regimes
and bringing their own workers, instead of employing locals.
Dreams of a future Cape to Cairo line
New plans could see the network extend even further south. Zambia sealed a deal with China
this month which could link up Zambia, Malawi and Mozambique in four years time, according to Zambia's department of transport.
However, travelers yearning for a trans-African Cape to Cairo railway may be disappointed. New railways are more likely to keep zigzagging from the coastal ports to mines and industrial districts inland, Grantham says.
"There has long been a dream of a Cape to Cairo railway, but the problem is that nobody actually needs to move any goods from Cape to Cairo, so realistically it's not a priority."