Concrete bridges are an important part of today's road infrastructure. An important part of those concrete bridges is to a large extent prefabricated. Precast concrete enables all the advantages of an industrialized process to be fully utilized. Contemporary concrete mixtures are used to realize high-strength bridge girders and piers that exactly meet the requirements set, both structurally and aesthetically, with a small ecological footprint. Sustainable and durable! On the construction site, there is no need for complex formwork, the execution time is drastically reduced and where road, water and rail traffic on or under the bridge has to be temporarily interrupted, it is only minimally inconvenienced during the execution of the project. Bridges capture the imagination. In addition to their pure functionality, overcoming a height difference, they offer designers unprecedented opportunities to shape their creativity, including when using precast concrete. This bulletin, prepared by the experts of Task Group 6.5 'Precast concrete bridges', takes a closer look at the conceptual (preliminary) design of prefabricated concrete bridges. The bulletin does not have the ambition to define the umbrella term 'conceptual design' but shows in a pragmatic way, using 24 examples spread all over the world, how leading designers use this methodology to select from the many possibilities to arrive at an ideal solution taking into account all design conditions. One often reads that experience is a necessary condition for good conceptual design. The pooled knowledge and experience in this bulletin already provide the reader with a good head start. Commission 6 thanks the former convener of the Task Group Hugo Corres, editor of this document, and the current co-conveners Marcello Waimberg and Ken-ichi Kata as well as all active members of the Task Group for sharing their knowledge and experience and for the successful realization of this bulletin.