Design a square poster that showcases the excitement of travel by fusing images of an airplane, bus, and train in a visually striking manner. The artistic style should combine digital art with impressionism, allowing for fluid brush strokes and vibrant colors that evoke a sense of motion and energy. Use high contrast lighting to create dramatic shadows and highlights, emphasizing the sleek lines of the airplane, the robust form of the bus, and the streamlined design of the train. The background should feature a collage of travel destinations, such as iconic landmarks and bustling transit hubs, creating a sense of adventure. Focus on the intricate details of each vehicle, such as the reflective surfaces of the airplane, the textured fabric of the bus seats, and the polished metal of the train. Apply color grading to enhance the vibrancy and excitement of the scene, and consider adding a subtle duotone effect to unify the composition.