Street reconstruction projects can be a pain for the citizens, causing noise, traffic jams, and accessibility challenges. We had the pleasure to work with the city of Helsinki using a design science research approach to analyse the current state of the projects’ performance and co-create a new model for shortening project durations.

We found out that the design-bid-build contract form was the main root cause of delays. The inflexible contract form does not work in projects with high uncertainty related to soil conditions, existing structures, and locations of utilities and the need for constant coordination between several parties, many of them being owners of the utility systems under the street.

Figure 1. A new project execution model for street reconstruction projects

As a result, we co-created with the city officials a new street reconstruction project execution model (Figure 1). The procurement is based on a target price with a bonus pool associated with project objectives. The model includes, among others, a collaborative development phase using Last Planner® System, a shared situation picture and an understanding of the decision-making process among actors, and joint risk analysis of all parties to react faster when risks occur. All entities managing design in the city and design consultants take part in the design phase. Also, construction managers participate in the final stage of the design. Finally, all construction managers participate in the preparation of construction.

The development phase plays an essential role. It allows the parties to define the project’s rules collaboratively and answer open questions. Last Planner is used for collaborative planning. In this phase, several parties are needed: design and construction managers, designers, main and other contractors. The deliverable of this phase is the risk management plan that is based on a collaboratively conducted risk analysis. Additional investigations in uncertain ground areas are a great way to confirm design assumptions and manage risks.

Finally, all construction managers and contractors take part in the construction phase, and designers are consulted when needed. The predefined risks and decision paths make collaborative decision-making easier and quicker, especially if decision-making power is given closer to the site, allowing the owner’s supervisor to make faster decisions without lengthy change order processes. Schedules need to be regularly updated and shared transparently with relevant parties using web-based scheduling systems.

These are all common features of lean construction projects. However, the starting situation was that there was no knowledge of lean practices, and for public clients, it is easier to use primarily cost-based evaluation of proposals.

Here the design science research approach was useful. It allowed the researchers to connect theory with the practitioners’ everyday working life. However, it is not a quick and dirty approach. Finding out the root causes was a lengthy process and necessitated extensive evidence from various sources, such as interviews, observations, a survey, and an archival study. Also, convincing the practitioners of the root causes and creating the new model required a lot of debate in several workshops. Was it worth it? Yes, certainly! The initial results of two projects were documented in a master thesis study and the initial findings were promising. The procurement was based on a target price, including a development phase.

We hope we have raised your interest in the new model for street reconstruction projects and especially how we were able to co-create it with the city officials. If yes, please feel free to browse through our IGLC article IMPROVING STREET RECONSTRUCTION PROJECTS IN CITY CENTERS THROUGH COLLABORATIVE PRACTICES.


Lehtovaara, J., Heinonen, A., Lavikka, R., Ronkainen, M., Kujansuu, P., Ruohomäki, A., Örmä, M., Seppänen, O., and Peltokorpi, A. 2020. “Takt Maturity Model: From Individual Successes Towards Systemic Change in Finland.” In: Tommelein, I.D. and Daniel, E. (eds.). Proc. 28th Annual Conference of the International Group for Lean Construction (IGLC28), Berkeley, California, USA,, online at

Lavikka, R., Seppänen, O., Peltokorpi, A., & Lehtovaara, J. (2020). Fostering process innovations in construction through industry–university consortium. Construction Innovation, 20(4), 569-586.

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Rita is a Senior Scientist at the Technical Research Centre of Finland (VTT). Her research focuses on decarbonise and digitalise the built environment.

Olli Seppänen is an Associate Professor of Practice at the Aalto University School of Engineering, Department of Civil Engineering. His field of expertise as a professor is operations management in construction. His research interests include real-time production control, location based management systems, prefabrication / modular construction and digitalized construction operations. Olli has been an active member of the International Group of Lean Construction, and was the Scientific Chair of the conference in 2015.

Joonas Lehtovaara is a Doctoral Researcher at Aalto University, Finland. His research focuses on construction planning and control methods, and especially on takt production theory and implementation.

Antti Peltokorpi is an Assistant Professor in the Department of Civil Engineering at Aalto University.