Many investments in infrastructure are built on the belief that they will ineluctably lead to poverty reduction and income generation. This entailed massive aid-financed projects, especially for the transport sector in developing countries. However the lack of robust evaluations raises the issue of a "one-size-fit-all" approach: Investing uniformly in Africa is likely to have a lower impact on poverty than expected. We use the second Cameroonian national household survey (Enquête Camerounaise Auprès des Ménages II, 2001) to address this question. Isolation from a tarred road is found to have no direct impact on consumption expenditures but a significant indirect one lies in the access to labor activities. Considering that diversification outside the agricultural sector is the main driver for poverty reduction in rural Africa, our results contribute to the idea that emphasis on roads investment should be given to locations where non-farming activities could be developed.