Amsterdam turns A10 into festival zone as heat prompts health warnings

A major stretch of Amsterdam’s A10 ring road is closed this weekend for Op de Ring, a massive festival celebrating the city’s 750th anniversary. The two-day event began Saturday morning with a highway race and a packed schedule of festivities, but medical experts have warned the city to cancel the run due to extreme heat, citing serious health risks.

The western, southern, and eastern segments of the A10 — from the A5 to the A1 interchanges — shut down Friday evening and will remain off-limits until Sunday afternoon. The closure makes way for Run op de Ring, a 7.5-kilometer race expected to draw 20,000 participants. Alongside the race, the festival features live music, multiple stages, sports events, and mass weddings, with 20 couples set to marry on the highway.

But with temperatures expected to climb to 31 degrees in the sun — and roughly 28 degrees in the shade — medical experts say the race could be dangerous. The paved highway, exposed to full sunlight, traps and reflects heat, creating what experts call the “asphalt effect,” which can cause temperatures to feel significantly higher at ground level.

“The heat increases above the asphalt, and on the ring there is no shade at all. That’s really a risk,” Silfred Hamilton, head of Medical Event Assistance, which provides on-site medical services for events including races, told Het Parool. “My advice to the municipality would be: cancel it.”

Hamilton warned runners not to push their limits and emphasized the need for constant hydration. “If you still participate, don’t run at your max,” he said. “But honestly, my advice would be not to run at all.”

Professor Maria Hopman, a physiologist at Radboudumc, said the human body is under serious strain during endurance sports in extreme heat. “Running is a high-intensity activity. Your muscles produce a lot of heat, and with all the heat from the concrete and the sun, your body can’t lose it properly,” she told Het Parool.

Body temperatures can climb to 42 degrees, at which point proteins in the body begin to break down, Hopman said. “Your nerve conduction is disrupted, people start to stagger, they lose focus, and in the next phase blood clotting is affected. Organs can start to fail, including the brain. In extreme cases, people can die or suffer permanent damage.”

She said the A10 route — from exit Watergraafsmeer (S113) to the RAI (S109) — offers little protection from the sun. “There’s a bit more wind up there since it’s outside the city, but almost no shade except near fencing,” she told Het Parool. Runners will pass buildings and the Amstelpark, but most of the course remains exposed.

In a letter, Mayor Femke Halsema said the city is closely monitoring the weather and could impose additional restrictions if temperatures rise further. It remains unclear whether cooling baths — recommended by Hopman — will be available at the finish line.

The festival’s organizers said they are adding water points along the route and setting up sunscreen stations. “That might help a bit, but it won’t always prevent overheating, ” Hamilton said.

Hopman urged runners to avoid racing for time. “Just jog or walk. Don’t go for a personal best — go for fun,” she said in a conversation with Het Parool. She also encouraged organizers to consider switching off timing equipment altogether. “And if you’re not feeling well, don’t start. If you’ve worked a night shift or slept poorly, don’t do it. That becomes a risk factor if things get critical.”

Hopman advised runners to start hydrating days in advance. “Drink enough on Thursday, Friday and Saturday. If you start dehydrated, you’re already behind.” She also encouraged light, breathable clothing and simple cooling tricks like a wet towel on the neck or dunking a cap under a faucet. “Cool your head — that helps,” she added. “Pre-cooling doesn’t last long, but repeated cooling can extend the effect.”

Other races across the Netherlands have already been canceled due to the heat, including the TT Marathon and TT City Run in Assen, which involved distances from 5.4 to 14.6 kilometers. “If those races are being canceled, then the municipality really needs to take another look at this one,” Hamilton told Het Parool.

The A10 closure has led to major traffic disruptions in and around Amsterdam. Motorists are being rerouted via the A1, A5 and A9, with travelers warned to expect more than an hour of additional travel time. Festivalgoers and visitors to the city are strongly advised to come by foot, bicycle, or public transportation. Dutch Railways (NS) had already warned of "very large crowds" on trains traveling to and from Amsterdam this weekend. The highway is expected to reopen at 3 p.m. Sunday after teardown is completed.