The Roads Economic Decision Model (RED) was developed under the Road Management Initiative (RMI), a key component of the Africa Transport Policy Program (SSATP) aiming at improving the decision-making process for the development and maintenance of low-volume roads. The model performs an economic evaluation of road investments options using the consumer surplus approach and is customized to the characteristics of low-volume roads such as a) the high uncertainty of the assessment of the model inputs, particularly the traffic and condition of unpaved roads; b) the importance of vehicle speeds for model validation; c) the need for a comprehensive analysis of generated and induced traffic; and d) the need to clearly define all accrued benefits. RED computes benefit for normal, generated, induced, and diverted traffic, and takes into account changes in road length, condition on the dry and wet seasons, geometry, surface type, and accident rates. Users can add to the economic analysis other benefits or costs such as social benefits and environmental impacts, if computed separately. RED is setup on a series of Excel workbooks, which collect all user inputs and present the results on an efficient manner, performing sensitivity, switching values and risk analyses. The current version of RED (Version 4.0), released in April 2018, which is available only in English, adds optionally CO2 emissions benefits or costs to the cost benefit analysis. RED version 3.2 is available in English, French and Spanish. With the same input data, both Version 3.2 and 4.0 produce the same results.