- Operator: Microómnibus Cuarenta y Cinco S.A.C.I.F., a national-jurisdiction line.
- Route: links Ciudad Universitaria with Remedios de Escalada (Lanús) via the Costanera, Aeroparque, Retiro, the Bajo, Constitución and Avellaneda.
- Branches: three. The A is regular and runs 24 hours a day; the B (Retiro – Remedios de Escalada, via the motorway) and the C (Ciudad Universitaria – Constitución) are express services with limited stops. The old D express to Retiro no longer exists.
- Ridership: about 32,900 SUBE trips on a typical weekday (August–September 2026).
- Fare: paid with SUBE by distance; with a registered card it ranges from $742.81 (up to 3 km) to $1,337.06 (over 27 km) from October 2026.
Line 45 branches and current routes
| Branch | Route | Service | Km | Frequency (peak) | Service hours |
|---|---|---|---|---|---|
| 45A | Ciudad Universitaria (C.A.B.A.) – Remedios de Escalada (Lanús) | Regular | 30 | ≤ 5 min | Every day, 24 h |
| 45B | Retiro (C.A.B.A.) – Remedios de Escalada (Lanús) via Autopista 9 de Julio Sur y Puente Pueyrredón |
Express | 19.5 | ≤ 26 min 30 s | – |
| 45C | Ciudad Universitaria (C.A.B.A.) – Plaza Constitución (C.A.B.A.) | Express | 16.4 | ≤ 28 min | – |
Routes and distances from the official CNRT fare tables and the Transport Secretariat resolutions in force (see Sources). The branch letter is shown on the bus sign.
Main points of branch 45A · Ciudad Universitaria (C.A.B.A.) – Remedios de Escalada (Lanús)
- 1Ciudad Universitaria
- 2Av. Costanera Rafael Obligado
- 3Aeroparque Jorge Newbery
- 4Av. Ramón S. Castillo
- 5Av. Antártida Argentina
- 6Metrobús del Bajo
- 7Av. Córdoba
- 8Metrobús 9 de Julio
- 9Constitución
- 10Av. Caseros
- 11Av. Vélez Sársfield
- 12Puente Victorino de la Plaza
- 13Av. Galicia
- 14Av. Hipólito Yrigoyen
- 15Estación Lanús
- 16Av. Coronel Rosales y 14 de Julio
Main points of branch 45B · Retiro (C.A.B.A.) – Remedios de Escalada (Lanús)
- 1Retiro (Av. Ramón S. Castillo)
- 2Av. Comodoro Py
- 3Av. Antártida Argentina
- 4Metrobús del Bajo
- 5Av. Córdoba
- 6Metrobús 9 de Julio
- 7Constitución
- 8Autopista 9 de Julio Sur
- 9Nuevo Puente Pueyrredón
- 10Av. Hipólito Yrigoyen
- 11Estación Lanús
- 12Av. Coronel Rosales y 14 de Julio
Main points of branch 45C · Ciudad Universitaria (C.A.B.A.) – Plaza Constitución (C.A.B.A.)
- 1Ciudad Universitaria
- 2Av. Costanera Rafael Obligado
- 3Aeroparque Jorge Newbery
- 4Costanera y Av. Sarmiento
- 5Costanera y Jerónimo Salguero
- 6Dársena D
- 7Retiro
- 8Estación Retiro (San Martín)
- 9Metrobús del Bajo
- 10Av. Córdoba y Florida
- 11Metrobús 9 de Julio
- 12Plaza Constitución
How many people ride line 45?
It ranks #67 out of 265 national and provincial AMBA bus lines by weekday trips.
Trips paid with a SUBE card, typical (median) value for August–September 2026. Source: Ministry of Transport open data.
Line 45 links Ciudad Universitaria, in the north of the city, with Remedios de Escalada, in the Lanús district. Along the way it passes the Costanera in front of Aeroparque, Retiro, the Bajo, Constitución and Avellaneda. This colectivo (city bus) is run by Microómnibus Cuarenta y Cinco S.A.C.I.F. and, according to SUBE open data, it records about 32,900 trips on a typical weekday in August and September 2026. It has three current routes, set by Resolution 801/2024 of the Ministry of Economy: one regular, the A, and two express services, the B and the C. This guide explains which one to take depending on where you are going.
Bus 45 route
The backbone of the line is branch A, the regular service. It leaves Ciudad Universitaria via internal roads and Av. Intendente Güiraldes, takes Av. Costanera Rafael Obligado, passes in front of Aeroparque Jorge Newbery and continues along Av. Ramón S. Castillo, Av. Comodoro Py and Av. Antártida Argentina to Retiro. From there it joins the Metrobús del Bajo, leaves it at Av. Leandro N. Alem and Av. Córdoba, and runs down the Metrobús 9 de Julio to Cochabamba. It passes Constitución, Av. Caseros and Av. Vélez Sársfield, crosses the Riachuelo over the Puente Victorino de la Plaza and enters Avellaneda along Av. Galicia. The final section runs along Av. Hipólito Yrigoyen to the terminus at Av. Coronel Rosales and 14 de Julio, in Remedios de Escalada. It covers about 30 km end to end.
On the return trip, towards Ciudad Universitaria, it runs up Av. Bernardo de Irigoyen and the Metrobús 9 de Julio, leaves it between Paraguay and Marcelo T. de Alvear, and passes Av. Santa Fe, Florida and San Martín before returning to Retiro and the Costanera.
Bus 45 to Ciudad Universitaria and Aeroparque
If you are going to Ciudad Universitaria or Aeroparque, two ramales (branches) will do. The 45A stops at every stop on the route. The 45C is an express between Ciudad Universitaria and Plaza Constitución that makes only 13 stops: Ciudad Universitaria, Costanera and La Pampa, Aeroparque (cargo area and passenger area), Costanera at number 1,200, Costanera and Av. Sarmiento, Costanera and Jerónimo Salguero, Castillo and calle 9, Dársena D, Retiro, Estación Retiro (San Martín line), Av. Córdoba and Florida, and Plaza Constitución. To get from Constitución or downtown to Aeroparque, the C is the option with the fewest stops. Route C is about 16 km long.
Semi-fast bus 45 via the motorway: branch B
The 45B is the express for the south. It leaves Retiro, on Av. Ramón S. Castillo between Antártida Argentina and Luisoni, and makes the regular stops through the Bajo and along 9 de Julio to Lima Este and Juan de Garay. There it joins the Autopista 9 de Julio Sur and crosses the new Puente Pueyrredón without stopping until Av. Hipólito Yrigoyen and Av. Galicia, in Avellaneda. After that it stops only at Hipólito Yrigoyen and Brasil, Jean Jaurès, Remedios Escalada de San Martín, Máximo Paz and Estación Lanús, and from the station to the terminus it makes the regular stops again. It covers about 19.5 km. It is a good choice if you are travelling between downtown and Lanús and do not need to get off on Av. Caseros or Av. Vélez Sársfield.
Timetable and frequency
The official resolution states that the regular services, that is, branch A, run 24 hours a day. At rush hour, while the express services are running, the A must run at intervals of between 3.5 and 5 minutes; outside those hours, between 3 and 4.5 minutes. For the express services, the rush-hour interval is 18.5 to 26.5 minutes on the B and 19.5 to 28 minutes on the C. The resolution does not publish the hours of the express services or a timetable per branch, so we do not give exact times.
SUBE data show the difference between days: about 32,900 trips on a weekday, 15,200 on a Saturday and 10,900 on a Sunday. There is much less service at weekends. Before you leave, check the next bus in the BA Cómo Llego app.
What changed on line 45 between 2024 and 2026
With Resolution 801/2024, published in the Boletín Oficial on 28 August 2024, the line was left with three routes. The D express, Ciudad Universitaria – Estación Retiro, disappeared, although it still appears on maps and apps with outdated data. If you see that branch anywhere, do not wait for it.
In 2026 a proposal was circulated to eliminate line 154 and merge its service into the 45, and for the B and C to stop being express services. At the time of this update it is still under review: there is no final resolution, so the current route is still the one described here.
Main stops and connections
The 45 passes several transport hubs. In Retiro, the C stops at Estación Retiro on the San Martín line, and the route continues along the Metrobús del Bajo and the Metrobús 9 de Julio, where you can connect with many other bus lines. At Constitución you can connect with the Roca train and subte (metro) line C. In the province, the B express stops at Estación Lanús on the Roca line.
The 45A runs along the Costanera Rafael Obligado and the 45C express has two stops of its own: cargo area and passenger area.
Terminus of branches A and C, which enter via the campus’s internal roads.
Terminus of the 45C, and the A and B pass through. Connects with the Roca train and subte line C.
Operator, phone and complaints
Line 45 is a national-jurisdiction line run by Microómnibus Cuarenta y Cinco S.A.C.I.F. It is overseen by the Comisión Nacional de Regulación del Transporte (CNRT). To complain about frequency, a bus that did not stop or poor service, call 0800-333-0300 or fill in the form at control.cnrt.gob.ar. Have the line, branch, time and, if possible, the vehicle number to hand. General strikes are called by the UTA (bus drivers’ union) and affect all lines in the AMBA; if you are searching for “línea 45 hoy” (bus 45 today), check the day’s news and the company’s official accounts.
The fare is paid only with SUBE and depends on distance. From October 2026, with a registered card, it costs $742.81 up to 3 km, $861.66 for 3 to 6 km, $1,002.80 for 6 to 12 km, $1,151.36 for 12 to 27 km and $1,337.06 over 27 km. Unregistered, you pay double. Tell the driver where you are going when you board.
Tips for riding bus 45
- For Aeroparque from Constitución or downtown, look for the 45C: it makes few stops and stops at both airport areas.
- Between downtown and Lanús, the 45B via the motorway is more direct, but it does not stop between Constitución and Avellaneda: if you are getting off on that section, take the A.
- At night or on a Sunday, count only on branch A and check the next bus in BA Cómo Llego.
- Use a registered SUBE card: unregistered, the ticket costs double.