As more people through different modes compete for the limited urban space that is set aside to serve transport, there is an increasing need to understand details of how this space is used and how it can be managed to improve accessibility for everyone. Ultimately, an important goal is to understand what sustainable level of mobility cities of different structures can achieve. Understanding these outcomes parametrically for all possible city structures and mixes of transport modes would inform the decision making process, thereby helping cities achieve their sustainability goals. In this paper we focus on the network capacity of multimodal systems with motorized traffic and extra emphasis in buses. More specifically, we propose to study how the throughput of passengers and vehicles depends on the geometrical and operational characteristics of the system, the level of congestion and the interactions between different modes. A methodology to estimate a macroscopic fundamental diagram and network capacity of cities with mixed-traffic bus-car lanes or with individual bus-only lanes is developed and examples for different city topologies are provided. The analysis is based on realistic macroscopic models of congestion dynamics and can be implemented with readily available data. (C) 2011 Published by Elsevier Ltd.