Keiyō is a kanjiacronym of two characters, each representing the two major urban areas connected by the route. The first character represents Tokyo (東京) and the second represents Chiba (千葉)
The route is officially designated as National Route 14 (Shinozaki Interchange to Anagawa Interchange) and a bypass for National Route 16 (Anagawa Interchange to the terminus). The section from the origin to Miyanogi Junction is classified as a road for motor vehicles only (自動車専用道路, Jidōsha Senyō Dōro), while the section from Miyanogi Junction to the terminus is classified as a national highway for motor vehicles only with national expressway concurrency (高速自動車国道に並行する一般国道自動車専用道路, Kōsoku Jidōsha Kokudō ni Heikōsuru Ippan Kokudō Jidōsha Senyō Dōro) as it is concurrent with the Higashi-Kantō Expressway Tateyama Route.[3]
Overview
The road is an important artery in the eastern part of the Tokyo urban area, carrying an average of 315,236 vehicles per day.[2]
The speed limit is 60 km/h on the section designated as Route 14, and 80 km/h on the section designated as Route 16.
Tolls
For the purposes of toll assessment, the road is divided into six sections. Usage of one section incurs a toll of 100 yen for passenger cars, light trucks, and 2-wheeled vehicles, 150 yen for large trucks and buses, and 350 yen for oversized vehicles. Traversing the entire road therefore costs 600 yen for a passenger car.[4]
The method of toll collection differs depending on the section of road used. From Shinozaki Interchange to Miyanogi Junction, toll booths at interchanges and toll gates on the main route are positioned so that a flat rate is charged at each station. From Miyanogi Junction to the terminus, tickets are issued upon entering the road which are used to calculate the toll at the exit point; this is the same system used on the Higashi-Kantō and Tateyama Expressways. Electronic Toll Collection (ETC) is accepted for payment, however commuter, off-peak, and late night discounts do not apply.