Seishō Bypass
西湘バイパス
Route information
Length	14.5 km[2] 1.8 km (Ishibashi Branch Route)[2] (9.0 mi) Main Route
Existed	1967[1]–present
Major junctions
From	Seishō-Ninomiya Interchange inNinomiya, Kanagawa Seishō Bypass (toll-free section) National Route 1
To	Hakoneguchi Interchange inOdawara, Kanagawa Odawara-Hakone Road National Route 1 Ishibashi Interchange inOdawara, Kanagawa National Route 135
Location
Country	Japan
Highway system
National highways of Japan Expressways of Japan

TheSeishō Bypass (西湘バイパス,Seishō Baipasu) (lit. WestShōnan Bypass) is atoll road inKanagawa Prefecture,Japan. It is owned and managed byCentral Nippon Expressway Company.

Officially the road is designated as a bypass forNational Route 1. It is also classified as a road for motor vehicles only (自動車専用道路,Jidōsha Senyō Dōro) and access is controlled with interchanges and junctions in a similar manner tonational expressways in Japan.

The road closely follows the coastline ofSagami Bay, facilitating access between theTokyo urban area and the city ofOdawara in western Kanagawa Prefecture. At the eastern terminus the Seishō Bypass continues as a toll-free road managed by theMinistry of Land, Infrastructure and Transport. In the west, the main route terminates near the resort town ofHakone, while a short branch route terminates at an intersection withNational Route 135 which leads to the resort town ofAtami and theIzu Peninsula.

The first section of the road was opened to traffic in 1967 and the entire route was completed in 1972.^[3] The main route has 4 lanes of traffic and the Ishibashi branch route has 2 lanes.

There are three toll collection points along the road. On the main route at the Tachibana Toll Plaza, a toll of 250yen is collected from regular passenger cars. At Kōzu Interchange these vehicles are charged 150 yen at the eastbound exit and westbound entrance. At Ishibashi Interchange 200 yen is collected.Electronic Toll Collection (ETC) is accepted for payment, however no discount programs are in effect.

In September 2007Typhoon Fitow caused extensive damage to the road, reducing some sections to two lanes of traffic and forcing the complete closure of other sections. The entire road was restored to full capacity on April 25, 2008.^[4]

• IC -interchange, JCT -junction, PA -parking area, TB -toll gate

Name	Connections	Dist. from Origin	Notes	Location (all inKanagawa)
Through to Seishō Bypass (toll-free section)
Seishō-Ninomiya IC	National Route 1	0.0		Ninomiya
Tachibana IC/ Tachibana TB/ Seishō PA	National Route 1	2.8	IC: Ninomiya-bound entrance and exit only PA: Ninomiya-bound only	Odawara
Kōzu IC/ Seishō PA	National Route 1 Pref. Route 72 (Matsuda Kōzu Route)	5.5	PA: Hakone-bound only
Sakawa IC	National Route 1	8.0	Ninomiya-bound entrance only
Odawara IC	National Route 1	9.6	Ninomiya-bound entrance, Hakone-bound exit only
Hayakawa JCT	Ishibashi Branch Route	11.6
Hayakawa IC		12.2	Ninomiya-bound entrance, Hakone-bound exit only
	Hakone Turnpike	↓	Ninomiya-bound entrance, Hakone-bound exit only
Odawara-nishi IC	Odawara-Atsugi Road	13.8	Local road access via Odawara-Atsugi Road only
Hakoneguchi IC	National Route 1	14.5
Through toOdawara-Hakone Road

Name	Connections	Dist. from Origin	Notes	Location (all inKanagawa)
Hayakawa JCT	Main Route	11.6		Odawara
Odawara Blue Way Bridge		↓
Ishibashi IC	National Route 135	13.4

• Central Nippon Expressway Company

• Toll roads in Japan
• 1967 establishments in Japan

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