Depending on the circumstances, transport modes can be competing or complementary over the transport market, the geographical market and the expected performance:
- Passengers and freight. Since both systems cover different markets, they are perceived as complementary since specific modes are designed to carry only passengers or freight (except air transport, where planes can carry both passengers and freight). In simple terms, a truck does not compete with a bus. However, passenger and freight modes can compete for the usage of infrastructures such as terminals and routes. In this case, a truck will compete with a bus for the usage of road infrastructure, particularly in situations of congestion where each vehicle will impair the mobility of others.
- International and domestic. Domestic transport modes are not designed to service international markets and vice versa. There is no significant example of competition between domestic and international markets. This is particularly the case if international transportation involves a maritime segment. Intermodal transportation helped improve the geographic complementarity by enabling a higher level of interaction between both circulation systems.
- Performance. Performance criteria usually cover a time and cost perspective, which is difficult to reconcile. For long distances, complementarity prevails, particularly for freight. Time-sensitive shipments are usually routed through air transport (some instances of long-distance trucking), while cost-sensitive shipments are routed through maritime or rail transport. For passengers, there is neither competition nor complementarity for long distances as the only practical mode remains air transport (it becomes a matter of integrating international and domestic segments). For shorter distances, competition prevails as different modes are possible for the concerned passenger and freight traffic.