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Started by mightyace, March 31, 2009, 04:53:00 PM

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Some may have heard of the Shin-Tomei Expressway (numbered E1A). It is being built as a bypass of the original Tomei Expressway (numbered E1) between Osaka and Tokyo, and is 228km long, excluding the 25km-long unopened section between Shin-Gotemba and Shin-Hadano (253km total). The total cost of the project is around $50 billion USD.

As with most expressways in Japan, it is tolled, and as non-ETC toll collection is still very common in Japan, the interchanges are all three-way with toll collection plazas, though most use ETC anyways. Some interchanges are ETC-only, called "Smart Interchanges" ("Smart IC").

Roundabouts are very uncommon in Japan, but the first roundabout interchange on a toll road was constructed in Iwata City, Shizuoka Prefecture, along the E1. The interchange, Shin-Iwata SIC, opened in 2021, and uses a roundabout at the ramp terminus for the top of the T, as well as a roundabout directly adjacent to the ETC toll booths.

Colored road markings help guide traffic through the roundabout to where they need to go. I like this and wish it was more common on US roundabouts.

Oddly, the ETC booths are before the roundabout, though there is a second scanner at the exits from the roundabout. If you don't have ETC, the booth lets you through into the roundabout, but a gate lowers at the exit and forces you around the roundabout back where you came from. As with many ETC-only interchanges, you have to stop at the scanner, hence the "STOP" writing on the ground (not "止まれ" which is more common...not sure why). This same gate configuration exists for outbound traffic. You can use the intercom to request re-entry onto the expressway if you exited by mistake; the gate across the roundabout exit lowers, and the one across the roundabout raises, allowing you to U-turn and continue back onto the expressway.

The pictures below are from Yahagi Construction, the company that built the interchange. More pictures can be found on their website, along with some testimonials from the designer and others involved.

Here is a Google Maps link to the interchange. Satellite imagery is out of date, but Street View is available.


This was the first expressway and probably so far only in Japan with a 120 km/h speed limit. The regular speed limit on Japanese expressways is 100 km/h.


Quote from: Chris on March 23, 2024, 04:33:15 PMThis was the first expressway and probably so far only in Japan with a 120 km/h speed limit. The regular speed limit on Japanese expressways is 100 km/h.

I drove the E51 Higashi-Kanto Expressway a couple weeks ago and it was posted at 120 km/h. Here is a post from the Chiba Police regarding the increase.

I think the E1A was the first expressway in Japan with a 120 limit, though it seems to be rolling out to more expressways. Still only 80 km/h in Okinawa.

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