The Trans-African Highway network comprises transcontinental road projects in Africa being developed by the United Nations Economic Commission for Africa (UNECA), the African Development Bank (ADB), and the African Union in conjunction with regional international communities. They aim to promote trade and alleviate poverty in Africa though highway infrastructure development and the management of road-based trade corridors. The total length of the nine highways in the network is 56,683 km.

Source

It's amazing how we hear so little about this.

Rossikk:

It's amazing how we hear so little about this.

I hear you.
Perhaps one plausible reason is that our minds are focused so narrowly on all that obtains outside Africa itself rather than within it.

I need more details about who is paying what and the interest rates and all of that. I don't like white elephant projects. I hope these roads aren't like NIgerian death trap road.s I also wonder who is creating thse roads? which firms?

Although lacking the granular details you want, there is some additional information on this WikiPage: http://en.wikipedia.org/wiki/Trans-African_Highway_network.

$413m Cameroon-Nigeria highway flagged-off
By Kunle Johnson Published 20/06/2010 News Rating: 
The  $413m 420 km Bamenda-Enugu road corridor which will link Nigeria and Cameroon countries has been flagged off.  The project, which was kicked-off  by the Minister for Works, Mohammed Sanusi Daggash and his Cameroonian counterpart, Bernard Avom  runs through  Bamenda  in Cameroon through Ikom, Abakiliki and Enugu in Nigeria.

The project, facilitated by the African Development Bank (ADB), the World Bank, the Japanese International Corporation Agency as well as the governments of the Federal Republic of Nigeria and the Republic of Cameroon among other things, intends to improve the already strained relationship between the two countries.

"The road is necessary to facilitate movement, commerce and to strengthen our economy and dilute the differences we have had for over 100 years." Dagash said.

According to him, on the Nigerian end, the corridor is made up of two segments. The first segment will be completed within 24 months and the second will be completed in 15 months.

It was gathered that work on the Cameroonian end had reached an advanced stage.

Minister of Public Utilities of the Republic of Cameroon described the launching of the programme as "tangible proof of the atmosphere of trust that now reigns between our two countries."

President of ADB group, Donald Kaberuka represented by Janvier Litse, regional director, West and Central Africa described the corridor as a step forward in implementing the NEPAD short-term action plan that aims at promoting accelerated growth and sustainable development.

Kaberuka said in order to sustain the works, plans have been made to build weighing stations and install weigh bridges, and in that regard encourag both countries to speed up measures aimed at harmonizing the axle load permissible on the roadway, to enable unhindered flow of cargo throughout the corridor.

Source: http://thenationonlineng.net/web2/articles/50391/1/413m-Cameroon-Nigeria-highwayflagged-off/Page1.html