Pavement design parameters under the influence of economic development: analysis of seasonal variability and evaluation of the average rate of increase in heavy vehicle traffic in Togo

The characterization of traffic for the dimensioning of road pavements in Togo comes up against a problem of traffic evaluation and its projection over time. In order to contribute to the credibility of the estimated traffic values, this work has set itself the objective of evaluating the proportion of induced traffic on the total volume of heavy vehicle traffic for new road improvements. In order to overcome the lack of statistical data on road traffic in Togo, the analyzes were based on economic growth over the period 2009 to 2018. Limiting the period to 2018 avoids possible biases due to the effect of the corona virus health crisis which began in 2019.An analysis based on data from field surveys, for eight sections of dirt roads to be developed, made it possible to assess normal traffic. Induced traffic is estimated on the basis of economic benefits through improved vehicle operating costs. The different results of the two sources of traffic (normal traffic and induced traffic) on the different road sections studied are very similar in terms of volume in the composition of the total traffic for the design of the pavements. Heavy vehicle traffic caused by the developments represents between 38% and 50% of total traffic. Assessing traffic growth on the basis of GDP growth gives average growth rates of 4.5%; 6.0% and 7.5% respectively in pessimistic, realistic and optimistic hypothesis.