The Rijnland route not only makes an important contribution to accessibility, quality of life and economic development in the region around Leiden, but also to underground construction in the Netherlands. When making decisions about the construction of the Rijnland route, Rijkswaterstaat, the province and the municipalities certainly did not take chances. There is no other path in the Netherlands for which so many alternatives and variants have been devised in recent decades.

Rhineland Route

First plan for the Rhineland route as early as 1958

The first drafts of the proposals for the Rijnland route can already be found in the Rijkswegenplan of 1958. During all that time there were constant protests from local residents, but due to increasing traffic jams on the N206, the Ir. G. Tjalmaweg, the business community in northern South Holland lobbied for at least as long to improve traffic flow on the east-west connection. The question is why, after decades of pleading with the neighbors, the Diputación still decided to carry out such an expensive project. Because according to the 2014 budget, the partly deepened, partly tunnelled route would already cost an amount of 931 million euros, but after correcting for inflation and solving a series of unforeseen setbacks, it amounted to more than a thousand millions.

Traffic flow around Leiden and Katwijk

Marjolein Vellekoop is a spokesperson for the Rijnlandroute on behalf of the province of South Holland. “Traffic pressure in the entire Holland Rijnland region and especially around Leiden and Katwijk had increased so much in recent years that a replacement alternative had to be found to solve the daily bottlenecks on the existing N206,” he argues. “With this new route we are building on the economic strengthening of the region and we are investing in the accessibility and quality of life in the area. The highway solves bottlenecks and guarantees traffic flow in the Holland Rijnland region, particularly around Leiden and Katwijk. For north-south traffic, the A4 and A44 motorways offer sufficient capacity for the expected increase in traffic over the next twenty years.”

Rhineland Route

Corbulotunnel is the gem

The architectural jewel of the new Rijnlandroute is the Corbulo tunnel, 2.5 kilometers long and 30 meters deep. The name of the tunnel refers to the Roman general who in the year 47 d. C. ordered the construction of a canal connecting the mouths of the Meuse and the Rhine in the Dutch delta. Parts of that channel remained in use until about 270. “Because of its many river tunnels, the Low Countries have a long tradition of sunken tunnels, but in this case a bore tunnel developed in Germany was chosen,” says Helmut Berkhout. , the Rijkswaterstaat contract manager who was responsible for outsourcing the extensive work. “We deliberately did not opt ​​for a sunken tunnel, because then we would have had to work on the surface for months, while a landscape integration was chosen that would be as light as possible for nature and for local residents.”

Rhineland Route

The drilling of the first tube of the tunnel took 6 months

In August 2019, the gigantic tunnel-boring machine, adorned with the traditional female name Gaia (the primeval mother of the ancient creation story), began its underground journey. “For bored tunnels, you have to look for that specialized expertise in the Alpine countries, because it is not available in the Netherlands,” says Berkhout. “Drilling the first tunnel tube took six months. The hundred meter long TBM was then transported back to the initial shaft to drill the second tunnel tube, which had to be completed in almost half the time. We had to drill under the Rijn-Schie canal, under two monumental buildings and houses, a swimming pool, under the Hague-Leiden railway and a high-voltage pylon. You can apply all sorts of calculations to that, but it was pretty exciting at times,” Berkhout laughs. “During the drilling, about sixty people worked continuously 24/7, because you don’t want subsidence to happen due to sudden pressure differences. 2,240 rings per tunnel tube were used, so a total of almost 16,000 concrete segments weighing 9,000 kilos each were pushed, picked up with vacuum tongs and placed in the tunnel shaft behind the eleven meter drill head. Each of seven segments formed a ring against which the drill shield was pushed forward at a rate of 58 millimeters per minute. The tunnel boring machine covered ten to fifteen meters per day in this way.”

Rhineland Route

For decades the Rhineland route was not a priority

When asked why the province took so long to give the go-ahead for its construction, Berkhout replies: “For decades, the process was not a priority for The Hague politics, or people did not expect the costs. As with all major road construction projects with different interests, it was not easy to reach a compromise that was widely supported on the Rhineland route. In early 2016, the two route decisions and the provincial integration plan were approved by the State Council. Naturally, many parties were involved in the planning process, but there were also strong supporters and opponents of the various alternatives, which meant that quite a few objections had to be addressed.”

Why Rijnlandroute will not open until the end of 2024?

At first glance, the Corbulo Tunnel already appears to be ready for commissioning in the short term, as originally planned, but due to some unforeseen setbacks, the completion of the Rhineland route has to be postponed for two years. “In fact, the intention was for the Rijnland route to be completed by the end of 2022, but due to a serious fire at the construction site in June 2022, the completion of the tunnel will take much longer than originally planned. As it stands now, the work will be completed sometime in late 2024,” continues Berkhout. “Just as the auto industry also had problems due to the war in Ukraine and the prolonged coronavirus lockdowns, many parts and machines destroyed by fire were also difficult to deliver. A few hundred meters of linear lighting, 130 cameras, smart switches, installation boxes, system components and many other construction materials needed to complete the tunnel were lost in the fire.”

exhaustive tests

This caused additional problems because the systems also had to be retested, explains Berkhout. “The security cameras had already been tested, but when we wanted to order new cameras, the tested cameras were no longer available. This means that all cameras, which took a long time to be delivered, have to be retested along with all other security cameras to see if they are compatible with all other security systems in the tunnel. Only when all this has been thoroughly tested can the permission of the municipality of Leiden be applied for.”

Air quality

According to the province, the assembly and connection of all the systems will take until the end of next year. “There are about 54 sub-installations in the tunnel, all of which are tested separately, for example to check if the tunnel image is correctly transmitted to the traffic control center or to check if all the systems can still work together,” Explain. Helmut Berkout. “For example, if an air quality meter measures that there is too much exhaust or smoke left in the tunnel, the fans should start running automatically to expel the smoke. There are still a number of security systems that he hasn’t just tested in a few days.”