Operationally, the time-definite freight delivery carriers collect less-than-truck-load shipments from shippers, consolidate and transport them through their line-haul operations networks, and deliver them to consignees within the time commitment on the shipments. To develop a cost effective line-haul operating plan is critical to time definite carriers who spend mult- billion operating expense yearly. Typically, a sequential three-phase planning process is adopted. It includes freight routing, trailer assignment and balancing, and feeder scheduling. The load planning problem is to simultaneously determine freight paths and a balanced trailer network for each of all types so that the total operating cost is minimized while the service commitment and operational restrictions are met. It integrates the first two phases. In this research, we formulate a link based integer program for the load planning problem. We also develop an implicit enumeration with ε-optimality algorithm. In the end, some of computational results on the top third time definite carrier in Taiwan are presented. The results are encouraging. Within reasonable computational times, the approach outperforms the Lagrangian Relaxation Decomposition approach in terms of the quality of solutions and the ability to identify infeasibility. It demonstrates that the approach is capable of becoming a planning tool for carriers in Taiwan to determine cost effective operating plans.