DUTCH infrastructure manager ProRail has tightened speed restrictions imposed at viaducts where cracks have been discovered on the northern section of HSL-South, the high-speed line that connects Amsterdam with the Belgian border.

The 120km/h speed restriction has been reduced to 80km/h at five of the 10 viaducts suffering from cracking. They are all located between the northern portal of the 8.67km Green Heart tunnel and the junction at Hoofddorp were HSL-South joins the conventional network.

The maximum speed on HSL-South is 300km/h. Speed restrictions were first imposed in July 2023 following the discovery of cracks in the viaducts, and have now been lowered following further investigation by ProRail.

The infrastructure manager continues to monitor the horizontal movement of the 10 structures concerned. It is very likely that they will need to be replaced, and ProRail expects work to be completed in 2026 at the earliest.

The new speed restrictions will delay trains by a further 2 to 3 minutes, producing total delays of up to 10 minutes for services on the northern section of HSL-South.

HSL-South is mainly used by Netherlands Railways (NS) domestic services and cross-border IC services to Brussels, as wells as Eurostar services to Paris and London.

NS has reacted sharply to the new speed restrictions, and says that journey times can only lengthen until a solution is found.

Discussions are now underway between NS, ProRail and Infraspeed, which maintains HSL-South, to determine if the number of services using the high-speed line should be further reduced as line capacity is restricted.

Viaducts and other structures on HSL-South were designed and built by Rijkswaterstaat, the civil engineering department of the Ministry of Infrastructure and Water Management.