DB (Design and build) and DBB (Design-bid-build) represent two different contracting forms in construction. The first provides the contractor degrees of freedom in design, which enables innovation. DBB is the safe and traditional contracting form, where the client is responsible for the design and the contractor builds accordingly.
Using a case study approach of five Swedish road construction projects, the present paper compares these contracting forms in terms of innovation. In this, the client's labelling of a contract being DB or DBB is taken at face value. It is established that the actual degrees of freedom for the contractors are highly restricted and that no important difference can be seen between the contracting forms regarding innovation. This implies that it is no reason to expect more innovation simply by labelling contracts as DB. Rational explanations for the usage of DB-contracts with bounds on the degrees of freedom are also suggested. Policy implications for promoting innovation in infrastructure contracting finalise the study.