This is a tentative proposal for an outer ring line in Budapest – probably a light metro line, such as the VAL. It would connect to the radial lines of the proposed Budapest urban-regional metro, and also to the proposed southern tangent line from Kelenföld Station to Kőbánya-Kispest Station, and the proposed eastern tangent line from Nyugati Station to Kőbánya-Kispest. The outer ring line would partly parallel the proposed Érd – Ferihegy S-Bahn tangent, and could form an alternative to it.
With 1,7 million inhabitants, Budapest is sufficiently large to justify this type of outer metro line. The general alignment is Budafok – Csepel – Pesterzsébet – Kispest – Kőbánya-Kispest Station – Kőbánya – Rákos station – Rákosfalva – Istvántelek – Rákospalota. For most of the route, it would follow existing main roads and rail lines, so the detailed alignment would have few variants. The line would be about 23-26 km long.
The proposed line would start at an underground station, under Budafok station, on line 40/30. (It could start further west, but that is not considered here). It would cross the Danube in tunnel – a bridge here is difficult, because of the built-up area on the opposite bank. The line would cross to Csepel Island, between the main channel and a secondary channel of the Danube. Its northern end is urbanised, and is a borough of Budapest.
Through the built-up area on the island, the line could follow an alignment under Karácsony Sandor utca and Katona József utca. That would allow interchange with HÉV at Karácsony utca station. The HÉV is a suburban rail line, planned for incorporation into a future metro line 5. A tunnel seems the only option for the line across Csepel: much of the alignment would pass through low-rise suburban housing, and the streets are relatively narrow.
The line would then cross the other arm of the Danube (Ráckeve-Soroksar branch). It is narrower, and a bridge is the best option. (There was once a HÉV line across this arm of the river, see the map of former lines). On the other bank, the line would cross the Kelebia railway line, and the HÉV line to Ráckeve. The Pesterzsébet station could be relocated, and a new HÉV station opened, to allow good interchange. This section of the HÉV might, in any case, be replaced by a new alignment, if the fifth metro line is built.
In Pesterzsébet, District XX of Budapest, the line would follow Nagysándor József utca, and then its continuation in District XIX / Kispest, Hunyadi utca. Between the two, the line would cross the main road out of the city, the Nagykőrösi út (leads to the M5 motorway). This would allow interchange with the proposed south-eastern urban-regional line along this highway. Here too, the housing is generally low-density, but the streets might allow a cut-and-cover tunnel.
In Kispest, the line would follow Hunyadi utca, and then Katica utca, to Kőbánya-Kispest Station. The line could possibly emerge from tunnel, and cross the rail lines next to the road bridge: otherwise a tunnel would be needed. The section from Budafok Station to Kőbánya-Kispest Station is 10 km long. It would be possible to build it as a light metro, and the rest of the route as an outer tangent S-Bahn line, along rail line 273. The alignment would be almost identical. The version described here is a light metro, over the rest of the semicircular route.
From Kőbánya-Kispest Station, the new line would run toward Rákos station (on line 80 and line 120). The alignment would first follow the Sibrik Miklós út, then pass through undeveloped areas. (This district of Budapest has a history of abandoned mine workings and garbage landfills). At Rákos station, the new line would cross the railway by bridge or tunnel, and then turn north-west, to connect to link line 273. It could partly follow Keresztún út, to the junction with the rail line, a tangential route.
The new line would now follow the tangential rail line 273. It would cross Kerepesi út, route of the HÉV. Interchange would be facilitated by a new or relocated station, near the existing Rákosfalva HÉV station. (This HÉV line might be replaced in the future by an extension of Metro line 2.
The line would continue along line 273 through districts XIV, XV, and XV. It would serving a restored Rákosszentmihály station, where it crosses Fogarasi út / Csömöri út. There would be a new station at the crossing with Drégelyvár utca (the planned alignment of new metro line 4), and possibly a station near the M3 motorway, serving Pestújhely.
The new line would terminate at Istvántelek station (giving 23 km total line length), or continue to the next station, Rákospalota-Újpest, 2 km further. There it could connect to metro line 3 (a short extension is planned). Both stations are on line 70, the main line northwards out of Budapest.