The Dutch logistics market is fragmented, with about 12,000 haulage firms. Last-mile delivery is the costliest stage of distribution, making up over half of total transport costs due to uneven demand, strict delivery windows, and last-minute bookings. This thesis investigates horizontal collaboration among logistics service providers (LSPs), where firms share capacity, depots, and routing data, though reluctance to disclose sensitive information remains a barrier.nnThree research areas are explored. First, an auction-based model shows that controlled information sharing and depot repositioning can significantly cut costs. Even limited disclosure yields 15–25 percent savings, while full disclosure approaches centralized planning efficiency. Second, a two-stage model addresses different booking horizons, reserving buffer capacity for late orders. This alignment reduces costs by around 30 percent compared with separate planning and reveals that a moderate buffer is optimal, though exact methods do not scale well. Third, a heuristic is developed to deliver practical solutions within hours, achieving 13–14 percent savings and reducing routes and travel distances.nnThe findings demonstrate that collaboration can generate substantial efficiencies even under partial data sharing. Auction platforms with disclosure limits, modest buffer policies, and scalable heuristics offer realistic ways for LSPs to lower costs and improve last-mile delivery performance.