Proposed here is a new urban-regional metro in Budapest, similar to the German S-Bahn and the French RER. It would unite all existing local services into Budapest, by constructing a new east-west line, and a new north-south-line. The north-south line would include a new line in the south-eastern suburbs: the rest links to services in and out of existing terminals.
Budapest already has a service which is often compared to the German S-Bahn: the HÉV or Helyiérdekű vasút. However, at present the HÉV consists of 4 separate lines: three along the Danube, and one to the east, to Gödöllő. The planned Budapest metro line 5 would link the Danube lines by a north-south link, passing east of the historic city centre of Pest (Belváros). It would possibly include the Esztergom line. Metro line 2 might also be extended along the HÉV line to Gödöllő, but there is no decision on this yet. The HÉV trains are fully segregated from the local services on the main lines to Budapest. It is those services which would use the tunnels proposed here – so this proposal is essentially independent of the planned metro line 5. The two tunnels can probably carry all existing and future suburban services around Budapest. The network principle is shown below:
The east-west line (red) would first use the existing line north from Kelenföld Station, like the proposed cross-city tunnel for Intercity trains. It would enter a tunnel near the Villányi út, and turn east to a station in the old city The exact location is problematic – the line must cross a new-north-south line, and existing metro lines 2 and 3. Several alternative alignments are possible, but for good interchange with the metro, the line should run as close as possible to the triple station at Deák tér (metro lines 1, 2 and 3). From the old town, the line would continue east to Keleti Station, the largest main-line station in Budapest.
The east-west line would in principle carry all suburban services passing through Kelenföld: Déli Station would be closed. On the other side, it would also carry all or most suburban services into Keleti. The exact configuration of lines is traffic-dependent. To simplify operation and improve alignment, the existing tracks to Kőbánya-Kispest, could be replaced by a new east to south curve near the national stadium, and extra tracks on the existing connecting line.
The north-south line (blue) would carry all suburban services entering Nyugati Station. At the south end, it would pass near the existing Ferencváros Station (on the Kelenföld – Keleti link line). It would run approximately alongside the marshaling yard south of this station, and then split. One branch would turn to join the Kelebia line, along the left bank of the Danube, via Soroksár. The HÉV line to Ráckeve runs parallel to the Kelebia line, as far as Dunaharaszti, where it crosses an arm of the Danube to the Csepel Island.
The other branch would be a new line along or under the Nagykőrösi út, the main road connecting to the M5 motorway, through the suburb of Pestszenterzsébet. In the south of Pestszenterzsébet it would link to the existing line to Gyál and Dabas, which continues to Kecskemét. (The Gyál line apparently ran on this alignment originally).
The alignment of the north-south line under the central area is shown below. It would start from an underground station at Nyugati Station, parallel to the proposed cross-city tunnel for intercity trains. It would turn southward to a station in the historic city centre, at Erzsébet tér, near the existing interchange stations at Deák tér. It would then run parallel to the Danube, to a station at Boráros tér. The exact location of the stations needs detailed study, but the route shown is at least clear of the crossing of the three metro lines at Deák tér.
On the image below, the future line 5 is shown as a green-white line, extending from the existing HÉV station Közvágóhíd, alongside the main road (Soroksári út) to Boráros tér (and on toward Kálvin tér). The new urban-regional line (white dashed line) would diverge from the approach track to the existing Ferencváros station, with a new station nearby, under Mester utca. At Boráros tér the two lines cross, with an interchange station.
The network of S-Bahn lines could be completed by a southern tangent line from Kelenföld Station to Kőbánya-Kispest Station, and an eastern tangent line from Nyugati Station to Kőbánya-Kispest. At that station, the lines could also connect to an outer ring line.