Optical burst switching (OBS) provides a feasible paradigm for the next IP over optical network backbones. However, due to its bufferless nature, OBS efficiency can be reduced by resource contention leading to burst loss. Several methods have been proposed to address this problem, most of them relying on reactive mechanisms which increase the complexity of core nodes, hampering scalability. In this work we consider a preventive traffic engineering approach for contention resolution which provides source routing with the objective of minimizing contention at the transmission links considering only topological information. This paper presents a simulation model aimed at the evaluation of different offline routing strategies in terms of burst contention. The simulation model is used to compare the performance of different novel path selection strategies with the traditional shortest path routing approach. Results confirm that the proposed strategies are effective in reducing the overall blocking and the model is feasible for the proposed QoS evaluation.