[Under Construction Tunnel] A report on the current state of the interior of the Ohtaki Tunnel in Chichibu City and the temporarily closed tourist spots.

The provisional use of the Otaki Tunnel before completion has been decided. In response to the traffic blockage caused by falling rocks on National Route 140 in Chichibu City, Saitama Prefecture, I went to report on the current state of the temporarily closed tourist spots, heading towards the Mitsumine Shrine from this tunnel that has been provisionally opened.

The circumstances leading to the provisional use of the Otaki Tunnel

In July 2025, a rockfall occurred on National Route 140 in the Otaki district of Chichibu City, Saitama Prefecture, causing a closure. National Route 140 connects the Tokyo area and Chichibu City to tourist destinations such as the Mitsumine Shrine and Otaki Onsen, and is a main road leading towards Yamanashi Prefecture, but it has no detours. Considering the long-term recovery and the impact on residents' evacuation and logistics, the Otaki Tunnel was provisionally made passable before its completion.

Source: Saitama Prefecture Western Kanto Road Construction Office.

The Otaki Tunnel is being constructed as part of the Western Kanto Expressway project, which connects Saitama Prefecture (Hanazono IC of the Kanetsu Expressway) and Yamanashi Prefecture (Shin-Yamanashi Ring Road). Excavation began in May 2022, and it broke through on March 19, 2024.

The closed National Route 140 has been a dangerous area, experiencing six major collapses and over twenty rockfalls in the approximately twenty years since 1998, and there has been a demand for new route securing from various parties.

Actually driving through the Otaki Tunnel

Although the surface inside the tunnel is somewhat undulating, it is flat enough that there is hardly any problem when driving through with a car. However, the speed must be below 15 km/h, and pedestrians, bicycles, motorcycles, and small cars are not allowed to pass. When I looked at the license plates of cars traveling in the opposite lane, I noticed many from within the prefecture, as well as those from Gunma and Ibaraki.

It took just a few minutes to exit the tunnel. If you turn right, you can head towards Mitsumine Shrine or Yamanashi, and if you turn left, you can go to Otaki Onsen. Some facilities at Otaki Onsen were temporarily closed, but it seems they have reopened in conjunction with the opening of this tunnel. I also saw several cars with prefectural plates heading toward the hot springs. Before the road was closed, I was coming here for interviews almost every week, so I was relieved to see that the lively atmosphere is gradually returning.

Heading towards Mitsumine Shrine to see the current situation of the tourist spot

This time, I will head towards the popular spot, Mitsumine Shrine, to check if the bustle of the tourist area has returned.

The image above shows the village parking lot located below the shrine. Even though it is a weekday, it seems to be about 60% full. I passed quite a number of cars on the way, so it seems that customer traffic has been significantly restored.

There were quite a few tourists at the tea house located just before the shrine. While the flatlands were experiencing a scorcher of a day, this tea house, situated at an altitude of nearly 1000 meters, was cool and a very comfortable place to be. In fact, it was my first time visiting, but upon arriving here, I felt like I understood why it is so popular.

This tea house also features ethnic menu items like amazake chai and green curry. It might be a good choice for those who want to enjoy a different flavor.

Finally, we visited the Nise Dam at the foot of the mountain to wrap up the interview. After looking into the Ohtaki Tunnel, which is not yet completed, I realized that infrastructure was being developed in ways that users are unaware of, which has made driving and tourism enjoyable.

I believe the provisional use of the Ohtaki Tunnel this time is the result of the behind-the-scenes efforts of those involved in the construction. Sometimes, it might be nice to reflect on the roads we drive on casually and enjoy the drive.

Interview / Text by Kazuma Tanaka

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