In the transportation system, carbon emissions are generated as a result of individuals' activity and travel choices. The simultaneous planning of transport networks (e.g., optimizing transit services) and land use (e.g., planning activity locations), along with the implementation of environmental policies, collectively influence individuals' activity and travel choices, thereby impacting carbon emissions. This paper presents a carbon credit charge scheme without initial credit allocations. Under this scheme, travelers are required to pay credits for emitting carbon dioxide and other greenhouse gases based on their chosen mode of transport, travel route, and departure time. We develop a bi-level programming model to capture the interaction between transit service headways, activity location plan, credit price, and their effects on individuals' activity and travel choice behaviors. In the upper-level model, we optimize transit service headways and activity locations as well as credit price to attain green mobility and equity goals. In the lower-level model, we account for travelers' heterogeneity in value of time and propose a comprehensive framework to schedule their activity and travel choice behaviors within a multimodal transport network using a time-dependent activity-based approach. With our proposed model, we comprehensively analyze the activity-travel choice behaviors of heterogeneous travelers and resulting carbon emissions. The application of our proposed model is demonstrated using the Nyguen-Dupuis network. Numerical results show that our proposed model effectively enhances transport management by modeling individuals' activity-travel choice behavior under the new transport policy.