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Open innovation for Diverging Diamond Interchange (DDI) in Denmark

DDI 12.00

Highway Interchanges are often highly congested. Solving it with traditional measures is costly. With the first Diverging Diamond Interchange (DDI) in Europe, road users change lanes when passing over the highway with fewer conflict points, enabling more capacity, improved safety and less congestion. The Danish DDI has a high return on investment. It was brought to life by an open innovation collaboration between the Danish Road Directorate and the Missouri Department of Transportation.

Innovation Summary

Innovation Overview

Diverging Diamond Interchanges were deployed in the US from 2009 to solve congestion problems in intersections.
The DDI's are unusual in that they require traffic in the intersection to briefly drive on the opposite side of the road from what is customary. By this, road users are ensured a conflict free left turn and increased traffic capacity in all directions. Travel times through DDI intersections are generally 30-40% lower and delays reduced by 70% as compared to other solutions.

The congestion at the intersection TSA 52 in Odense, Denmark had been problematic and unacceptable for several years and had experienced frequent situations with queueing back from the intersection onto the highway. This lead to dangerous situations on the highway that is part of the Scandinavian-Mediterranean Corridor in the European Union. A project to solve the congestion challenge was initiated, but found itself in constraint after it became clear that increased traffic numbers would require a costly extension of the bridge over the highway, thereby exceeding the budget. Unable to find a viable solution in Denmark, the project team decided to scout for new solutions abroad.

A scout-team was sent to the annual meeting of the Transportation Research Board in Washington in January 2015, where it learned about the US experience and know-how from DDI's in operation. Based on the American experience and personal contacts with employees at the Missouri Department of Transportation, The Danish Road Directive decided to initiate a pilot project to test the solution in Odense.

In November 2015, a cross-functional Danish team went on a study trip to the Missouri Department of Transportation to discuss the project design of a DDI at the intersection in Odense. After the study trip, visiting ten DDI's in Kansas City and St. Louis, an iterative process started with workshops, tests and technical assessments towards the construction phase of the intersection. Significantly for the success of the project, several draft versions of the construction project was sent to Missouri Department of Transportation for comments and ideas.
As a result, the first DDI in Europe, at the intersection TSA 52 in Odense, was opened after two years of open innovation between the Danish Road Directorate and the Missouri Department of Transportation.

The main objectives of the project were to design a DDI, while preserving the existing highway bridge and respecting the interests of the local community, close to the project area. A key, technically complex problem of the project was the "crossing over" of traffic to the other side of the road and the "crossing back" to the right lane.

In the design process, the crossing points were enlarged and optimized after literature reviews, interviews with American experts. As a result, the crossing points were moved further away from the bridge, enhancing the capacity of the project and traffic safety, but also increasing the impacts on the landscape. In order to reduce the impacts on the local community, the team decided to adopt a unique, asymmetric design. By this, an entirely new variant of the innovation was invented.

From a traffic safety perspective, key challenges were how to make the road self-explaining and how to make the road users familiar with the design. Here again, literature reviews, interviews and the workshop with US and Danish cross functional teams proved efficient tools for problem-solving and optimization of the project design.

The main benefits of the project are for road users in the local community of Odense and for road users on the highway:

• Reduced queueing back from the intersection to the highway and increased traffic safety
• Increased capacity, especially for traffic crossing the bridge and turning left from the intersection to the highway
• Reduced congestion, resulting in reduced fuel consumption and air pollution
• Reduced travel time by approx. 50% through the intersection
• Reduced construction time
• The DDI in Odense is future-proofed in terms of capacity for the next 15 or more

Thanks to the open innovation, DDI constructions are now part of the Danish toolbox for dealing with congestion at highway intersections.

Innovation Description

What Makes Your Project Innovative?

In the Danish Road Directorate, we realized a need of finding a new solution to an old problem: congestion. We also realized that we would most likely not find the solution in Denmark. Hence, we decided to adopt international, open innovation with important benefits:

• It enhances the availability of new solutions
• It reduces time to implementation for innovations
• Provides access to competencies

The Danish Road Directorate maintains several strategic routes to open innovation European and Global networks through NVF, CEDR, EU, FEHRL, CEN, PIARC and TRB. In the case of the DDI intersection, highly capable information brokers from the Danish Road Directorate connected to relevant networks at the annual TRB conference, scouted for and found new ideas.
Most importantly, the Danish Road Directorate also succeeded in empowering members of staff to start and develop collaboration with outstanding competencies in the Missouri Department of Transportation

What is the current status of your innovation?

Problems and opportunities were reviewed and tested by the Danish project team and the team in the Missouri Department of Transportation. The technical problems to be solved were mainly to translate the design of traffic islands, road markings, visual guidance, glaring and curve radius into a Danish context.

The project was implemented and successfully opened September 2017.
The post-project evaluations indicate that the DDI intersection at Odense SV has had significant effects since it was opened: Not alone have queues in the area been reduced. The increased capacity is also higher than expected, travel time has been reduced by 50% and the intersection has proven cheaper than traditional intersections that would require vast and expensive constructions over the highway. In spite of the new way of driving, no traffic safety issues have been detected. The Danish Road Directory is monitoring the construction closely and will continue to do so in the future.

Innovation Development

Collaborations & Partnerships

Collaborators involved in the innovation process were government officials. The main collaborations of the open innovation were the Missouri Department of Transportation, The Danish Road Directorate and the Municipality of Odense. Additionally, data from the Utah Department of Transportation were made available to the project.

Users, Stakeholders & Beneficiaries

The users of the innovation are mainly citizen and companies in Denmark and mainly commuters, who have experienced:

• Reduced queueing back from the intersection to the highway and increased traffic safety
• Reduced congestion, resulting in reduced fuel consumption and air pollution
• Reduced construction time with little to no additional right-of-way needed to retrofit an existing interchange.

Innovation Reflections

Results, Outcomes & Impacts

With the innovation, the Danish Road Directorate has reduced queues and travel time in the project area significantly. The Danish Road Directory is currently conducting the final impact evaluations. Initial findings show an decrease in average travel time by almost 50%.

The lessons learned have been discussed and diffused widely within the Danish Road Directorate and in Denmark through conferences, social media, national television, radio and governmental webpages.

Based on the initial success of the project after its opening in 2017, a national screening of other, potential applications of the DDI-design in Denmark will be conducted in the near future. After the construction of the DDI in Denmark, three DDI's are being considered in the Netherlands.

Challenges and Failures

In spite of all benefits of the innovation, the DDI raises a number of challenges as compared to traditional constructions.
The DDI requires more physical space and establishes large, superfluous areas, which was critical in the context of the densely populated project site in Odense. It also requires a substantial amount of markings and signs, which was contradictory to the European concept of the self explaining road, where the driver is encouraged to naturally adopt behaviour consistent with design and function.

The collaboration between Danish and US experts was also challenged by differences in traffic safety standards. In a DDI, commuters have to learn how to find their way safely and the risk of wrong-way driving was identified as a key risk by the Danish team. Although US experience showed that wrong-way driving was not an issue, the Danish team was only convinced after a long collaborative dialogue of rethinking the DDI construction in a local, Danish context.

Conditions for Success

Leadership decisions: In The Danish Road Directorate to solve the congestion problem at Odense through open innovation to endorse close collaboration with an American organisation; In The Missouri Department of Transportation to share its innovation, data and experience. This was motivated by the enthusiasm to share their experiences and added value to DDI-development in Missouri that access to Danish case stories could provide.
Social infrastructures: The Danish Road Directorate maintains several international, strategic routes to open innovation through Nordic, European and Global networks with sustained top-leadership buy-in. In this case, the annual Transportation Research Board in Washington became a key framework for the important story telling about the innovation.
Human factors: The adaptation of the innovation to a Danish context was only made possible thanks to a relationship of trust, enthusiasm and curiosity between Danish and Missourian individuals.


The DDI is very likely to be replicated in the Danish network of state roads as it is now considered as a new standard in the Danish guidelines for planning and design, construction and maintenance of roads.

Further, there is a high potential for replication in other European countries, especially due to its high return of investment. In the Netherlands alone, the construction of three DDI's is being considered.

Lessons Learned

The lessons learned by the Danish Road Directorate are that:

• To find new, promising solutions to grand challenges, it is helpful to search, work together and learn from one another in an international and even global context.
• Even mature innovations abroad are not "off the shelf items" that can simply be copied and applied. Substantial adaptations to local contexts are necessary
• With the open innovation, the Danish Road Directorate demonstrated that the organisation is able to leave the "Not Invented Here"-syndrome and shift to "searched for and found elsewhere, and proudly implemented here".
• Open innovation should be considered an innovation itself. Consequently, open innovation should be effectively managed from the beginning to achieve an ‘innovation implementation climate’ and increase efficiency and implementation .

Anything Else?

The case study illustrates the story of how the Danish Road Directorate aims at playing a role of leadership in the Danish transportation sector now and in the future. It also illustrates how we as an organisation are ready to get out of our comfort zone and allocate resources for innovation.
For the Danish Road Directorate, innovation is much needed to be able to understand and profit from societal and technological developments as well as changes in what our "customers", road users and other citizen want from us. As the DDI- case story goes, being enthusiastic about learning and getting inspired by others both domestically and abroad, daring to experiment, test and implement innovations rapidly, are critical ingredients in this process. Another example of our thinking as innovation-led change as absolutely critical is Climate-friendly Asphalt Experiment of the Danish Road Directorate, a promising innovation process that we hope to be able to present in 2019.

Project Pitch


  • Identifying or Discovering Problems or Opportunities - learning where and how an innovative response is needed
  • Generating Ideas or Designing Solutions - finding and filtering ideas to respond to the problem or opportunity
  • Implementation - making the innovation happen
  • Evaluation - understanding whether the innovative initiative has delivered what was needed
  • Diffusing Lessons - using what was learnt to inform other projects and understanding how the innovation can be applied in other ways
Call for Innovations Call for Innovations
This case was submitted as part of the Call for Innovations, an annual partnership initiative between OPSI and the UAE Mohammed Bin Rashid Center for Government Innovation (MBRCGI)

Innovation provided by:


Date Published:

5 November 2017

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