1. Introduction
In the construction industry, there are various contracting models, and one of the most commonly used is the DBB model – Design-Bid-Build. This traditional model has for years been the standard in both public and private projects worldwide, including in our region. Its main characteristic is a sequential approach: first the design is developed, then the contractor is selected through a bidding process, and only afterwards does construction begin.
2. Structure of the DBB Model
The DBB model consists of three main phases:
- Design
The investor engages a designer (architect and/or engineers) who prepares the complete project documentation: conceptual, main, and detailed design. The designer may be engaged directly or through a public tender.
- Bidding
Once the project documentation is complete, the investor issues a call for bids for the execution of works. Contractors submit their bids, which include price, deadlines, and technical capacity. The contract is usually awarded to the most favorable bidder, although criteria may also include quality, references, and other factors.
- Construction
After the contractor is selected and the contract signed, the construction phase begins according to the previously defined design. The investor may appoint a supervising engineer to ensure that the works are carried out in compliance with the project and applicable regulations.
3. Key Stakeholders in the DBB Model
- Investor – finances the project, decides on the engagement of the designer and contractor, and manages the project (or delegates this to a project manager).
- Designer – prepares the project documentation and may also participate in construction supervision.
- Contractor – executes the construction works based on the approved documentation.
- Supervision (engineer or legal entity) – monitors the quality of works, compliance with the design, and compliance with laws.
4. Advantages of the DBB Model
- Clear division of responsibilities: the designer and contractor have well-defined roles and responsibilities.
- Transparency in public procurement: the model is particularly suitable for public projects as it enables open competition and comparability of bids.
- Control over design: the investor retains full control of the project before selecting the contractor.
- Established practice: DBB is a well-known and widely accepted model with a solid legal and technical foundation.
5. Disadvantages of the DBB Model
- Time inefficiency: the sequential approach means projects take longer – construction cannot start until design and bidding are completed.
- Risk of misunderstandings: since the designer is not contractually bound to the contractor, disputes and interpretation issues may arise.
- Challenges with changes: if modifications are needed during construction, they can increase costs and cause delays.
- Limited contractor innovation: as the contractor does not participate in design, there is less flexibility and innovation in execution.
6. Comparison with Alternative Models
- Design and Build (D&B): a single entity (or consortium) both designs and builds. The main advantage is faster project delivery due to overlapping phases, but the investor has less control over design.
- Construction Management (CM): the investor hires a construction manager to run the project, while contractors are engaged for specific packages of work. This offers flexibility but requires an experienced investor.
- Integrated Project Delivery (IPD): all key stakeholders (designer, contractor, investor) are involved from the early planning stages and share risks and rewards. This is more complex but potentially more efficient.
7. Practical Application of the DBB Model
DBB is often used in:
- Public infrastructure projects (roads, schools, hospitals) – due to transparency and cost control.
- Smaller projects with simple and well-defined requirements.
- Projects where the investor wants full control over the design before construction begins.
In countries where public procurement and legal frameworks emphasize clear procedures and tendering, DBB is often the preferred or even mandatory model.
8. Conclusion
The DBB model remains a fundamental contracting method in the construction industry due to its clarity, predictability, and strong legal foundation. While it is not the fastest or most modern approach, its robustness, transparency, and wide applicability keep it relevant. However, with the increasing complexity of projects and the need for greater flexibility and faster delivery, investors are more frequently considering alternative contracting models.
For investors who wish to retain full control, minimize risks during the design stage, and ensure a transparent bidding process – DBB remains a safe choice.
Author: Aleksandar Sajic
