ツーリングと山歩き#4| 静岡県掛川市隧道巡り
Hi! This time, I visited tunnels in Kakegawa, Shizuoka pref., Japan. Kakegawa City in Shizuoka Prefecture is located almost in the middle between Japan’s two major cities, Tokyo and Osaka, also between Shizuoka and Hamamatsu, the two largest cities in the prefecture. It’s a so-called “center city,” where major transportation routes like the Tokaido Shinkansen, Tokaido Main Line, Tomei Expressway, Shin-Tomei Expressway, and National Route 1 all cross east to west. With Shinkansen Station, Entrance of high way, and easy access to Mt. Fuji Shizuoka Airport, it’s a place blessed with excellent connectivity from old period. Back in the Edo period, it prospered as a post town on the Tokaido—the country’s main artery of travel. To the north and south ran the “Salt Road,” carrying salt produced in Sagara, Makinohara City up to Shinshu area. This route was also called the “Akihakaido”, a pilgrimage path to Akiha mountain Shrine, dedicated to the fire-prevention deity. Because east-west and north-south routes crossed here, Kakegawa became a thriving hub of travel and trade. However, Kakegawa is also full of mountains and hills, making it a difficult place for transportation. At the border between Kakegawa and Shimada lies Nakayama Pass (Sayo no Nakayama), one of the three hardest passes of the Tokaido along with Hakone and Suzuka. The hilly terrain required many tunnels and cuttings to be built. Because older tunnels were narrow and low, later generations built replacements, leaving behind layers of history. Today, Kakegawa still has many old roads and abandoned paths, with a surprising number of tunnels that attract enthusiasts—it’s even known as a “paradise of tunnels.” This time, I visited 5 well known tunnels with my motorcycle. ① Iwaya Tunnel Construction date unknown. Length: 64m, width: 1.6m, height: 2.0m. So narrow it feels dangerous even on a motorcycle. One side is reinforced with corrugated steel pipe, the other is raw rock. The inside is rough and bumpy, almost cave-like. Its origins are mysterious, with some saying it might have been used as an air-raid shelter during the war. On the other side lies Suijin-Tengu Shrine. The floor can be muddy, so vehicles must take care. Riding through on my bike had my heart pounding—it was truly thrilling. *spider web I turned around in front of Suijin Shrine and returned to the original road. On the way in I used my high beams, but on the way back I only had normal headlights, and it felt darker and scarier than I imagined. *careful.. careful.. Interestingly, the tube-shaped part of the tunnel gave me a strange sense of security. I read some reviews saying people drove through here by car—which I think pretty crazy. ② Aota Tunnel Built in 1895 (Meiji 28). Length: 224m, width: 4.0m, height: 3.0m. Once an important route known as the Sagara-Kakegawa Line. Entirely brick-built up to the ceiling, with white-painted walls giving it a two-tone look. Today, a new tunnel carries most traffic, but Aota Tunnel is still well-maintained and used by cyclists and pedestrians. In stark contrast to just a moment ago, this place gives me an overwhelming sense of safety. ③ Yaginota Tunnel Built in 1932 (Showa 7). Width: 2.2m, height: 2.0m. Located close to Aota Tunnel. Like Iwaya, the ground is muddy and narrow, so vehicles should be cautious. One side is natural rock, with concrete reinforcement in the middle, and it exits into a cutting road. Interestingly, the plaque uses the unusual characters “墜道” instead of the standard “隧道” for “tunnel.” took a cool pic XD Since this tunnel is surrounded by tea fields, I believe it was originally made for people working in the tea industry. It seems far too narrow for regular traffic, yet when I stopped to take photos, I was astonished to see car tire marks left in the muddy ground. ④ Hinokizaka Tunnel Built in 1905 (Meiji 38). Length: 47m, width: 3.6m, height: 3.2m. Unlike Aota, which has been repaired in places, this tunnel still retains its original plaque and stonework. Today, it’s used as a school route. About a 10-minute walk away, near an elementary school, you’ll find a monument to the old Salt Road. By the way, this is the only tunnel I chose to walk through, simply because I found it the most impressive and wanted to experience it slowly on foot. Although some of the bricks have started to peel away, it’s truly remarkable that the tunnel has maintained its form for over a century. The ivy climbing over the entrance also adds a beautiful sense of character to the tunnel, which I really liked. ⑤ Ganshoji Shrine Tunnel Built in 1905 (Meiji 38). Length: 137m, width: 3.6m, height: 3.2m. Like Aota, it has a two-tone design and preserves its original stonework and plaque. Nearby, in the woods off the old road, lies an even older tunnel nicknamed “Ushigatani no Jimichi,” said to date back to 1879 (Meiji 12), along with old cutting road, But judging from the overgrown weeds—and my dislike of spiderwebs and bugs—I had to skip that exploration. I managed to pass through every tunnel I had planned to visit. This journey made me realize that the tunnels, which once supported the lives of people in the past, still stand today, and continue to play a role in the lives of the local community. It truly made this trip worthwhile. The Aota, Hinokizaka, and Iwaidera tunnels are recognized by the Japan Society of Civil Engineers as part of the “2800 Most Important Civil Engineering Structures” in modern Japanese history. They’re just about a 10–15 minute drive from the Tomei Kakegawa IC, or around 15 minutes from the Shin-Tomei Mori-Kakegawa IC. If you’re touring or driving in west Shizuoka, these tunnels make for a fascinating stop. Thank you!
静岡県掛川市は、東海道と塩の道（秋葉街道）が交差する交通の要所として古くから栄えてきました。
山や丘が多い地形のため、数多くの隧道や切通しが築かれ、今も旧道や廃道に歴史あるトンネルが残されています。
かつて交通の難所を越えるために築かれた隧道群が今も静かに佇むその姿は、掛川の歴史と人々の営みを伝え続けています。
訪れたトンネル：
① 岩谷隧道
② 青田隧道
③ 八木ノ田墜道
④ 檜坂隧道
⑤ 岩井寺隧道
青田隧道、檜坂隧道、岩井寺隧道は「日本の近代土木遺産・現存する重要な土木構造物2800選に選定されています。
アクセス：東名掛川ICから約15分、新東名森掛川ICからも約15分ほどで到着可能