1. A method for adaptive planning of a transportation service comprising: sending a transportation proposal to a set of organizations, the proposal including a set of initial options, each initial option including a set of variable parameters for specifying a transportation service; providing for each organization to select values for one or more of the variable parameters to generate at least one modified option, and for making a commitment for at least one of the modified options, conditional on the organization-selected values for the variable parameters; providing for each organization to send respective modified options to commuters of that organization; receiving responses to the modified transportation proposal, at least some of the responses including pledges by the commuters for at least one of the modified options based on the organization-selected values for the variable parameters and optionally on commuter-selected values for the variable parameters; computing a cost-benefit function for each of a set of revised options for the transportation service, each of the revised options being based on a combination of the variable parameters for which pledges which cover the combination have been received; and outputting at least one of the revised options based on the cost-benefit function.