Shibayama Railway Line

The nihongo|Shibayama Railway Line|芝山鉄道線|Shibayama Tetsudō-sen runs for 2.2 km between Higashi-Narita Station and Shibayama-Chiyoda Station, much of it underneath Narita International Airport. There are plans to extend this line farther to the southeast in the future, eventually to Kujukuri Beach on the Pacific Ocean coast of Chiba Prefecture.

Although the line is independently owned by the Shibayama Railway, it functionally resembles an extension of the Keisei Electric Railway; the line is operated using equipment and crews leased from Keisei, Shibayama-Chiyoda Station is designed to resemble a Keisei station, and trains continue to Keisei Narita Station past Higashi-Narita. During rush hours, limited express trains run from Shibayama-Chiyoda through the Keisei Line and Toei Asakusa Line to terminate at Haneda Airport Station on the Keikyū Airport Line.

As the line passes underneath the airport, it is often patrolled by police.