A grand union is a rail track junction where two double-track railway or tramway lines cross at grade, often in a street intersection or crossroads. A total of sixteen railroad switches (sets of points) allow streetcars (or in rarer installations, trains) coming from any direction to take any of the three other directions. The same effect may be achieved with two adjacent wyes if the location allows for space.
Complexity These types of complex junction are expensive to build and expensive to maintain. Special parts, sometimes made of manganese steel, are needed for each location where one rail crossed another (a "frog"); these parts often need to be custom-made and fitted for each single location, depending on the specific angle of crossing of the intersecting streets.
A full grand union junction consists of 88 frogs (where one rail crosses another rail), and 32 switchpoints (point blades) if single-point switches are not used. A tram or train crossing the junction will encounter four or twenty frogs within the space of crossing the junction.
For all of the possible tracks of a grand union to be used during normal operation, at least six different tram routes have to cross the union. In an intersection with lines oriented towards cardinal directions, these could be: north-south, north-east, north-west, south-east, south-west, and east–west.
Three-quarter, half and butterfly unions Three-quarter unions are similar to grand unions in that they are also rail track junctions where two double-track railway lines cross at grade, often in a street intersection or crossroads; the primary difference being that one corner of the crossing does not have curved junction tracks, with the union having a total of 12 railroad switches (sets of points).
Half unions are similar, but have curved junction tracks on only two adjoining corners of the intersection, with a total of eight switches.
Butterfly unions share the total of eight switches, but the curved junction tracks are on opposing corners.
Examples
Europe Austria (0) Vienna has a three-quarter union at Quellenplatz, 48°10′32.3″N 16°22′24.7″E
Belgium (1) Brussels has a grand union at carrefour Buyl – Général Jacques, 50°49′05.9″N 4°22′45.8″E
Croatia (1) Zagreb has a grand union at the intersection of Savska and Vodnikova Street, 45.80545°N 15.96627°E, and a three-quarter union at the intersection of Vukovarska and Držićeva Avenue, 45.80113°N 15.999°E.
Czech Republic (4) Brno, has a three-quarter union at 49°12′16.24″N 16°37′25.54″E. Olomouc, has one grand union at 49°35′44.42″N 17°14′50.27″E. Prague, has three grand unions, first at 50°6′12.65″N, 14°28′23.89″E the second at 50°5′55.94″N, 14°25′59.76″E. and the third at 50°4′23.19″N 14°24′50.30″E, this Grand Union was rebuilt in 2003 and has curved trackwork as the streets are not aligned at the river crossing.
Estonia (0) Tallinn has a butterfly union at the intersection of Narva maantee, Hobujaama and A. Laikmaa streets at 59°26′14.07″ N 24°45′26.21″ E. The new crossing line started service in 2024 and connects the city harbor to the rest of the system.
Finland (0) Helsinki has a three-quarter union at the intersection of Simonkatu and Mannerheimintie, 60.1699°N 24.9385°E, and a butterfly union at the intersection of Runeberginkatu and Mannerheimintie, 60.1817°N 24.9273°E. These are probably the northernmost unions in the world.
Germany (12)
Bremen has a full grand union under construction at the stop Bennigsenstraße at 53°4′13.8″N 8°51′22.2″E. It is used since August 2025, full usage will be from approximately 2028. Cologne has one grand union at the stop Aachener Straße / Gürtel at 50°56′13.2″N 6°54′30.4″E, and one three-quarter union at Barbarossaplatz 50°55′42.9″N 6°56′33.7″E Cottbus has one grand union at 51°45′39.86″N 14°19′51.39″E and a three-quarter union at 51°44′57.54″N 14°19′42.50″E. Dresden has two grand unions at 51°3′49.47″N 13°44′48.95″E (Albertplatz) and 51°2′58.09″N 13°44′39.27″E (Hauptbahnhof), two three-quarter unions at Fetscherplatz and Könneritzstraße/Jahnstraße as well as a five-eighths union at 51°3′47.55″N 13°44′13.53″E Duisburg has a butterfly union at Marxloh, Pollmann at 51°30′7.44″N 6°45′25.78″E Kiel had a half union on Berliner Platz. Erfurt has a butterfly union at 50.976099°N 11.034358°E, its modern city center: the Anger. Karlsruhe's system has the most in Germany, with four grand unions at Stop Mathystraße (49°0′8.96″N 8°23′39.77″E), at Entenfang (49°00′37.1″N 8°21′31.8″E)., at intersection Rüppurrer Straße and Baumeisterstraße, and at the adjacent intersection at Stop Rüppurrer Tor. A three-quarter union is at Stop Tullastraße, two half unions at Weinbrennerplatz and Eberstraße and a butterfly union at Durlacher Tor. Kassel's system has a single grand union at 51°19′4.87″N 9°30′1.02″E and a three-quarter union at 51°18′43.02″N 9°29′29.64″E. Leipzig has a grand union at 51°20′39.35″N 12°22′15.99″E it is unique in interfacing with four tracks at Goerdelerring tram stop. There is a three-quarter union at 51°19′56.49″N 12°20′19.68″E, a half union at 51°20′31.31″N 12°21′31.15″E and butterfly unions at 51°19′12.95″N 12°19′48.80″E, 51°20′20.36″N 12°21′44.96″E and 51°21′44.93″N 12°21′55.79″. Munich has one real grand union at Ostfriedhof since the last track alteration in 2015 at 48°07′8.6″N 11°35′1″E. A three-quarter union can be found on Leonrodplatz at 48°09′34.2″N 11°32′50.8″E. While not a traditional grand union, the Munich tram system has also a "grand circle" which has the same route function as a grand union and also provides a loop for all lines, it is at Maxmonument in Maximilianstrasse, 48°8′15.27″N, 11°35′17.02″E.
Italy (2) Milan: the Milan tram network currently has two grand unions. The first is a non standard design with divided North South tracks around a monument at piazza 24 Maggio, and the second located nearby at piazzale Porta Lodovica.In summer 2022 it is going to lose one of the diverging tracks. Works ongoing. There used to be another large one until the 1990s at piazza della Repubblica, but it has since reduced to a wye junction still keeping the layout of diverging routes by the removal of the straight route to via Vittor Pisani. Rome: This network does not have a Grand Union but a Grand Circle, at the Porta Maggiore, east of Roma Termini railway station.
Netherlands (4) Amsterdam, Netherlands: , the Amsterdam tram system continues to have four grand unions. However, none of them has tram routes running in all directions under normal operation. They are at 52°21′17.39″N 4°54′4.49″E;https://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=52%C2%B021%2717.39%22N+4%C2%B054%274.49%22E&aq=&sll=37.926868,-95.712891&sspn=33.816707,79.013672&ie=UTF8&ll=52.354844,4.901218&spn=0.000423,0.001717&t=k&z=20 Google Maps: Van Woustraat 83III 1074 Amsterdam, the Netherlands 52°21′45.91″N 4°52′31.04″Ehttps://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=52%C2%B021%2745.91%22N++4%C2%B052%2731.04%22E&aq=&sll=52.352854,4.89117&sspn=0.000423,0.001206&ie=UTF8&ll=52.362792,4.875219&spn=0.000423,0.001206&t=k&z=20 Google Maps: Eerste Constantijn Huygensstraat 98 1054 Amsterdam, the Netherlands and 52°22′12.13″N 4°51′0.94″E.https://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=52%C2%B022%2712.13%22N++4%C2%B051%270.94%22E&aq=&sll=52.362857,4.875219&sspn=0.000423,0.001206&ie=UTF8&ll=52.37002,4.850273&spn=0.000423,0.001206&t=k&z=20&layer=c&cbll=52.370064,4.850241&panoid=MEYZKi8jBNVh2LMqNmB2-w&cbp=12,246.16718307695862,,0,5 Google Maps: Jan Evertsenstraat 144II 1056 Amsterdam, the Netherlands and 52°21′9.99″N 4°53′28.04″E;https://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=52%C2%B021%279.99%22N++4%C2%B053%2728.04%22E&aq=&sll=52.355027,4.901474&sspn=0.000598,0.001206&g=52%C2%B021%2717.39%22N+4%C2%B054%274.49%22E&ie=UTF8&ll=52.352804,4.89117&spn=0.000423,0.001206&t=k&z=20 Google Maps: Ceintuurbaan 55–157 1072 Amsterdam, the Netherlands Rotterdam: the Rotterdam tram system has one three-quarter union, at Vasteland – Westzeedijk 51°54′41.4″N 4°28′39.0″E;https://maps.google.com/maps?q=51.911494,+4.477485&hl=en&sll=51.911483,4.477728&sspn=0.002862,0.008256&t=h&z=16 Google Maps: Vasteland – Westzeedijk Rotterdam, The Netherlands The Hague: The Hague tram system has one butterfly union at the crossing of the Laan van Meerdervoort and the Koningin Emmakade/Waldeck Pyrmontkade (S100), (52°04′54.1″N 4°17′15.9″E). There is also a half union at the crossing of the Loosduinseweg and the Monstersestraat, (52°04′22.2″N 4°17′30.5″E)
Poland (15) Kraków has four grand unions, one at Rondo Grzegórzeckie (50°03′27.42″N 19°57′32.40″E), one at Starowiślna (50°03′23.40″N 19°56′43.63″E), one at Rondo Kocmyrzowskie im. ks. Gorzelanego (50°04′46.65″N 20°01′38.49″E) and one at Rondo Czyżyńskie (50°04′24.31″N 20°01′02.89″E). There is a "grand circle" at Plac Centralny im. Ronalda Reagana (50°04′19.56″N 20°02′14.46″E) which has the same route function as a grand union and also provides a loop for all lines. There is a three-quarter union at Stradom (50°03′06.26″N 19°56′30.22″E). Poznań: The Poznań Tram system has 6 grand unions, which may be the most extant in any city. They are at: 52°24′37.94″N, 16°54′48.53″E;https://maps.google.com/maps?q=52%C2%B024%2737.94%22N,+16%C2%B054%2748.53%22E&hl=en&ie=UTF8&ll=52.410529,16.913557&spn=0.000439,0.001206&sll=52.407766,16.912468&sspn=0.000439,0.001206&t=k&z=20 Google Maps: Franklina Roosevelta 11, Poznań, Poland 52°24′28.02″N, 16°54′44.97″E;https://maps.google.com/maps?q=52%C2%B024%2728.02%22N,+16%C2%B054%2744.97%22E&hl=en&ie=UTF8&ll=52.407766,16.912468&spn=0.000439,0.001206&sll=52.402659,16.889031&sspn=0.000439,0.001206&t=k&z=20 Google Maps: Rondo Kaponiera, Poznań, Poland 52°24′9.54″N, 16°53′20.65″E; 52°23′24.39″N, 16°53′39.07″E; 52°22′48.68″N, 16°56′35.21″E and 52°23′57.53″N, 16°57′8.97″E. All can be seen in detail on Google Earth. Warsaw: The Warsaw system has four grand unions, first at 52°14′30.79″N 20°59′37.00″Ehttps://maps.google.com/maps?q=52%C2%B014%2730.79%22N++20%C2%B059%2737.00%22E&hl=en&ie=UTF8&ll=52.241881,20.993619&spn=0.000441,0.001206&sll=52.236994,20.980161&sspn=0.000441,0.001206&t=k&z=20 Google Maps: 629 Warszawa, Poland second at 52°14′13.30″N 20°58′48.62″E,https://maps.google.com/maps?q=52%C2%B014%2713.30%22N++20%C2%B058%2748.62%22E&hl=en&ie=UTF8&ll=52.236994,20.980161&spn=0.000441,0.001206&sll=52.254707,20.982457&sspn=0.000882,0.002411&t=k&z=20 Google Maps: Rondo Kercelak, Warszawa, Poland third at 52°22'01.84"N, 21°00'49.14"E, and fourth at 52°18'87.92"N 21°00'20.16"E. There is a three-quarter union at 52°15′17.24″N 20°58′57.11″E,https://maps.google.com/maps?q=52%C2%B015%2717.24%22N+20%C2%B058%2757.11%22E&hl=en&ie=UTF8&ll=52.254707,20.982457&spn=0.000882,0.002411&sll=48.137884,11.588259&sspn=0.000961,0.002411&t=k&z=19 Google Maps: Rondo Zgrupowania AK "Radosław", Warszawa, Poland and 52°26'35.68"N 21°02'07.88"E. Wrocław has one grand union at 51°07'01.6"N 17°02'31.3"E. There are also three-quarters unions at 51°06'04.8"N 17°01'45.3"E, 51°06'16.5"N 17°01'19.6"E, 51°06'41.9"N 17°01'18.3"E and 51°07'03.5"N 17°01'54.8"E
Russia (0) Kazan: Kazan Tram system had one grand union. It is at 55.780459 N, 49.112853 E. Street View in Google Earth shows that this Grand Union has been partially removed, portions still remain in the pavement in 2013.https://maps.google.com/maps?q=55.780459,49.112853&hl=en&ll=55.780444,49.113012&spn=0.00081,0.002411&sll=55.780459,49.112862&sspn=0.00162,0.004823&t=k&z=19 Google Maps: 55.780459 N, 49.112853 E Moscow: Moscow Tram system has one three-quarter union on Preobrazhenskaya Ploshadhttps://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=moscow&sll=-34.928621,138.599959&sspn=1.020084,1.683655&ie=UTF8&hq=&hnear=Moscow,+Russia&ll=55.795831,37.714243&spn=0.000683,0.001644&t=k&z=19 Google Maps: Preobrazhenskaya Ploshad, Moscow Russia