"Alternative systems allowed, if within rules"

The renovation of the Afsluitdijk now has some beautiful, innovative solutions. The result of smart thinking and great collaborations. Such as the solution that was found for being able to realize the narrow guide rail tested in asphalt full scale. Danny Kraak is Project Manager at BAM Infra Verkeerstechniek and tells us: "In 2017, I was allowed to participate in the tender, regarding the traffic measures and the guide rail. A great challenge, as the requirements called for special solutions. Rijkswaterstaat's call for tenders stated 'alternative systems allowed, provided they are within the rules'. That gave us the opportunity to think 'out of the box' and with success."

Artist Impression of the reinforced Afsluitdijk with the new road profile of the A7.

Road design played an important role within the tender

Due to the narrow median strip, there was a need for a guide rail, placed in asphalt, fully tested. "With the freedom -within frameworks- we were given, that's when the idea was born," Danny outlines. "From there, I took on the director's role. Together with Ruurt Veldman, Project Manager Team Road and Bridges at Levvel (BAM/Van Oord/Rebel), I fleshed out the idea, we looked for the right supplier and were then able to present an integral road design. Before Christmas in 2017, we won the tender. Within the tender, the road design played an important role."

The preliminary award followed in March. "That means you have to make everything you've thought of come true. Together with Saferoad, our supplier, we started zooming in on the possibilities and discussed the tests that were needed. We attended simulations and physical tests, which was particularly impressive. In the end, we arrived at a CE-marked guide rail construction, mounted in asphalt. In the process we were also appointed as the installing party, we expect to start in June."

Adding value in the tender

Ruurt Veldman takes over: "I myself work at BAM Infra Multidisciplinary Contracts. We work within Levvel in six teams; I am Project Manager Team Road and Bridges. In the tender, the focus was mainly on flood safety, which is why the dike is being raised and widened. The flood resistance of the dike must be guaranteed, which is why we are using asphalt in the central reservation. From that, the question arose again to apply a center guide rail mounted in asphalt. Now it is true that the road is originally tight, with narrow emergency lanes. There we could well offer our added value, we want to ensure that more space is gained. Since the dike does not allow for expansion in terms of infrastructure, we have now found the solution in widening the road in the area of the median strip and applying a median strip guide that is significantly narrower, but perfectly meets all requirements. It has become the new SafeStar 241d from Saferoad."

The guide rail after the crash: passed with flying colors!

The solution was sought -and found- in the median strip

Originally, the Afsluitdijk contained a green strip with rainwater runoff as a median strip. "To improve the water resistance even more, we came up with the idea of asphalting the middle lane as well. Together with the narrow center guide rail, this gives us driving and emergency lanes 350 cm wide. A concrete barrier is not desirable, for the drainage of water in case of flooding and because of aesthetic requirements. This fully justifies the new median strip guide rail construction we came up with. In Saferoad we found a good supplier, they had exactly the guide rail we were looking for with the SafeStar. Together we searched for the solution to apply it in asphalt. After we submitted the idea in the tender phase, Saferoad calculated everything and we were able to offer the design; if approved, we could then continue the development. Our idea was considered the best, we could start designing. That required putting our money where our mouth was, so a lot of computing power and extensive simulations and testing."

A year of development, simulation and testing

The creation of the new guide rail did not happen overnight. Live crash tests were conducted in Poland, at the guide rail factory, with independent testing bodies present. Ruurt: "That ultimately provided us with a fully CE marked product." Herman Odijk of Saferoad says of the construction, "The posts of the guide rail are driven through the asphalt. The boards are attached to the posts with shear bolts, which results in a strong rail combined with a low injury index Asi A for passenger cars. In the event of an impact, the guide rail keeps the vehicle in the direction of travel. At only 28 cm wide, this is the narrowest guide rail on the market, which fully meets the current stringent requirements of the Department of Public Works when impacted."

Ruurt Veldman (left) and Danny Kraak, with a bus deployed for the crash test in the background.

Not only safe, but also sustainable

Because it is a DBFM project, Levvel is obligated to provide 25 years of maintenance for the Afsluitdijk. "We get paid according to the availability of the facilities," Ruurt explains. "The guide rail we jointly developed fits that picture perfectly. In terms of durability, we also score well. The zinc layer provides excellent protection against corrosion, the rail causes less inconvenience to road users, we were able to say goodbye to the standard ground median -so no work on mowing the median - and we can install the posts using a GPS-controlled fully automatic piling machine. Tight, straight, precise and fast." Added Danny, "The method of placement is as unique as the product and solution itself. The boards weigh quite a lot, so they are better placed mechanically. That requires less physical labor, so less risk of injury. Sustainability is increased by omitting concrete, because this new construction is completely recyclable."

Longest construction site

The Afsluitdijk is the longest construction site the Netherlands has ever known. To work safely, construction traffic is split from road traffic. "We are directing traffic along the work area during the work using a 2-0 system. We go from two times two lanes per carriageway to two lanes on one carriageway. This way we are tackling work sections of 5 kilometers at a time. In two years, when the dike is completed, traffic is expected to have experienced little disruption all this time, Ruurt concludes.