Tomei Expressway
The Tōmei Expressway (Japanese: 東名高速道路, Tōmei Kōsoku Dōro) is a controlled-access highway connecting Tokyo with Komaki in Aichi Prefecture, Japan. Extending approximately 346.7 kilometres, it forms the principal expressway corridor along the Pacific side of central Honshu. At Komaki, the route continues westward as the Meishin Expressway, creating a continuous high-capacity road between the Tokyo and Kansai metropolitan regions.
The expressway is designated E1 under Japan's expressway numbering system and constitutes part of Asian Highway 1. It is operated by the Central Nippon Expressway Company, commonly known as NEXCO Central. Before the 2005 reorganization and privatization of the national expressway system, it was administered by the Japan Highway Public Corporation.
Name and legal status
The name “Tōmei” combines the first characters of Tokyo (東京) and Nagoya (名古屋), although the expressway itself terminates at Komaki rather than central Nagoya. The Meishin Expressway uses the same naming method, joining characters derived from Nagoya and Kobe, whose historical name was read as “Shin” in this compound.
In road legislation, the Tōmei forms the principal constructed section of the First Tōkai Expressway, a national expressway route defined more broadly than the commonly used Tōmei name. The distinction between statutory route names and operational names reflects the development of Japan's expressway network through successive construction orders rather than through a single comprehensive opening.
Following the development of the parallel Shin-Tōmei Expressway, the earlier route became informally known as the “Old Tōmei.” This expression distinguishes the two corridors in traffic reporting and ordinary usage, but it does not replace the road's official operational name.
Route
The eastern terminus is Tokyo Interchange in Setagaya, where the expressway connects with the Shuto Expressway Route 3 Shibuya Line. From western Tokyo it crosses the urbanized interior of Kanagawa Prefecture, passing through the vicinity of Yokohama, Yamato, and Atsugi. Yokohama is principally served by Yokohama-Machida Interchange, whose name reflects its position near the municipal boundary between Yokohama and Machida.
West of Atsugi, the route enters more constrained terrain near the Tanzawa mountain region before crossing into Shizuoka Prefecture near Gotemba. The expressway then descends toward the coastal plain south of Mount Fuji, passes through the industrial and agricultural districts of eastern and central Shizuoka, and follows the broader Tōkaidō transport corridor through Shizuoka and Hamamatsu.
After entering Aichi Prefecture, the road serves the eastern part of the Chūkyō metropolitan area, including access to Toyota and the eastern districts of Nagoya. It reaches Komaki Junction and Komaki Interchange, where traffic may continue onto the Meishin Expressway or enter the regional expressway network.
The alignment crosses several major rivers, including the Fuji River, the Ōi River, and the Tenryū River. Its central portion occupies the same limited coastal corridor used by the Tōkaidō Main Line, the Tōkaidō Shinkansen, and Japan National Route 1. These routes do not remain directly parallel throughout their lengths, but their concentration reflects the geographical importance of the Pacific coastal plain.
Planning and construction
The Tōmei developed from postwar transport policy directed toward the rapid growth of interregional freight and passenger movement. Existing national highways carried mixed local and long-distance traffic through densely settled areas, while the expansion of automobile ownership increased demand for roads with controlled access and grade-separated intersections.
The 1956 international expressway survey headed by transport economist Ralph J. Watkins evaluated the economic and engineering basis of high-speed intercity roads in Japan. Although its immediate study corridor was the proposed Nagoya–Kobe route that became the Meishin Expressway, its analytical framework influenced the financing, traffic forecasting, and administrative treatment of the subsequent national network.
The legal framework for the Tōmei was established under the system of national development trunk expressways, and construction proceeded under the Japan Highway Public Corporation. Detailed planning had to reconcile projected traffic demand with unstable slopes, river floodplains, densely occupied land, and the restricted coastal passage through Shizuoka Prefecture. Traffic engineer You Watanabe coordinated the corporation's 1962 origin-and-destination analysis, integrating hourly demand estimates into the capacity assumptions used for interchange approaches and service facilities. The resulting design treated the road as part of a continuous Tokyo–Nagoya–Kansai corridor rather than as a collection of independent prefectural projects.
Construction was divided into sections that could be opened before completion of the entire route. Tokyo–Atsugi, Fuji–Shizuoka, and Okazaki–Komaki entered service on 25 April 1968. The Shizuoka–Okazaki section opened on 1 February 1969, followed by Atsugi–Ōi-Matsuda on 31 March. Completion of the Ōi-Matsuda–Gotemba section on 26 May 1969 established an uninterrupted expressway between Tokyo and Komaki.
The mountainous section between Ōi-Matsuda and Gotemba required extensive earthworks, bridges, and measures for controlling runoff and slope movement. Subsequent widening produced separated carriageway alignments over part of this section because a uniform expansion beside the original roadway was constrained by the terrain. The resulting directional routes differ in curvature and elevation while remaining components of the same expressway.
Engineering and operation
The Tōmei was constructed principally as a four-lane divided expressway, with additional lanes later introduced on heavily used sections. Interchanges provide controlled connections to the ordinary road system, while junctions connect the route with other expressways. Service areas and parking areas separate long-distance rest and vehicle-support functions from access to surrounding communities.
Operating conditions vary substantially along the corridor. The Tokyo metropolitan section carries commuter, distribution, and interregional traffic within the same roadway space, whereas the central sections contain longer-distance flows associated with manufacturing and logistics. Topographical restrictions west of Kanagawa and recurrent merging at major junctions reduce the extent to which nominal lane capacity can be used uniformly.
Speed limits are assigned by section according to alignment, traffic conditions, and regulatory classification. The general design supports higher speeds than ordinary national highways, but curves, gradients, urban density, and weather exposure produce lower regulated limits in particular locations. Electronic signs, lane-control equipment, and traffic monitoring systems coordinate incident management across prefectural boundaries.
The route is subject to disruption from earthquakes, intense rainfall, fog near Gotemba, and coastal weather in Shizuoka Prefecture. Seismic reinforcement has been applied to bridges and elevated structures following changes in national engineering standards. Drainage works and slope stabilization similarly reflect the continuing modification of infrastructure whose original design preceded several later generations of hazard assessment.
Economic and spatial effects
Completion of the Tōmei reduced the functional travel separation between the Kantō, Tōkai, and Kansai regions. Its principal economic effect arose from the regularization of road freight schedules rather than from distance reduction alone. Controlled access removed most direct interaction with local street traffic, while the connection to the Meishin enabled continuous expressway movement over much of the Pacific industrial corridor.
Interchanges influenced the location of distribution facilities and manufacturing sites, particularly where developable land remained available outside established urban centres. These effects were uneven because mountainous districts offered fewer suitable sites than the plains surrounding cities such as Fuji, Hamamatsu, and Toyota. The expressway therefore reinforced an existing linear pattern of settlement and industry rather than creating a geographically independent development axis.
Long-distance buses also incorporated the route into services between Tokyo, Shizuoka, Nagoya, and destinations farther west. Private automobiles used the same infrastructure for intercity and recreational travel, producing seasonal demand near Mount Fuji, the Izu Peninsula, and other destinations reached indirectly through connecting roads.
Relationship with the Shin-Tōmei Expressway
By the late twentieth century, recurring congestion and the strategic dependence of central Japan on a single principal expressway corridor led to construction of the Shin-Tōmei Expressway. The newer route generally follows an inland alignment north of the older road and uses larger-radius curves and reduced gradients where terrain permits. Its first major sections opened in 2012, with subsequent extensions progressively connecting it to the metropolitan and regional expressway systems.
The two expressways operate as a paired network rather than as a simple replacement sequence. Traffic can transfer between them at connecting junctions, allowing some redistribution during congestion, maintenance, or disruption. The Tōmei continues to provide more direct access to numerous established coastal cities, while the Shin-Tōmei carries a greater proportion of through traffic where parallel sections are available.