This paper proposes an analytic continuous model to evaluate the modifications of distribution costs caused by the implementation of Urban Consolidation Centers (UCC) in a dense area of a city. Freight flows from interurban carriers are consolidated and transferred to a neutral last-mile carrier to perform final deliveries. This operation would reduce both last-mile fleet size and average distance cost. The general case of carriers with different market shares is analyzed resulting in no significant differences from the equal market case. The trade-off between savings in the system and a minimum market share per company is also analyzed.