border with Rwanda at Rusomo Falls ( (entirely paved): From Nzega in the Tabora Region, the B-3 road leads to the Rwandan border (). Kigoma and the border with Burundi at Manyovu: The road is entirely paved. Mwanza and Musoma ( entirely paved): The B-6 road connects these cities and then proceeds north to the Kenyan border. Arusha and Namanga on the Kenyan border (: The A-104 road is entirely paved. Iringa and Mbeya ( entirely paved): The A-104 road links these cities, with its terminus in Tunduma on the Zambian border. Trunk roads in Tanzania were marked by numbers following the two-tier number system with prefixes A- and B-, as is practiced in the rest of East Africa. Following is the list of Tanzanian trunk roads. Meanwhile, Tanzania has introduced a numbering system for trunk roads using numbers starting with "T" but so far the "A" designations are visible if at all. Regional roads Mtwara Region: Paved roads link Mtwara and Masasi and from there almost to Nangoma. An unpaved road then leads to Mtambaswala and the modern Unity Bridge on the Mozambique border. The African Development Bank in April 2012 approved a loan to Tanzania to pave this road, followed in April 2013 with an additional loan of 7.659 billion yen (US$77.9 million) from Japan. Western regions are the most poorly served, with no paved highways except locally in Kigoma and Ujiji. Only one dirt road runs down the western side of the country, it is just a track between Kasulu and Sumbawanga and prone to flooding south of Mpanda. Between Tunduma in the south-west and Nyakanyazi junction near Kibondo in the north-west, a distance of nearly 1000 km, there are no highways in the centre of the country. International highways The Cairo-Cape Town Highway, Highway 4 in the Trans-African Highway network, runs between the northern town of Namanga on the Kenyan border and the Zambian border town of Tunduma in the southwest, via Arusha, Dodoma, Iringa, and Mbeya. The section between the entrance to Tarangire National Park and Iringa has been recently paved between Babati-Kondoa-Dodoma-Iringa. There is no longer a need to traverse a longer eastern route from Arusha to Iringa via Moshi and Morogoro is paved. This route is versus for the Arusha-Dodoma-Iringa route. In the southwest, from Iringa to Tunduma, the Cairo-Cape Town Highway follows the Tanzam Highway linking Zambia and Dar es Salaam. Rail