Six MTC routes carry passengers down GST Road from Guindy to Tambaram and beyond, and the most frequent of them, 21G, runs 60 trips a day in each direction at an average gap of about 7 minutes, according to its route page. South of Tambaram the choice thins out to three routes that continue to Vandalur and Guduvanchery, and one, 500, that runs all the way to Chengalpattu.
The road is also the city’s airport corridor, so this guide notes where the buses meet the Blue Line metro and the new feeder and AC electric services announced in 2026. Frequencies in this guide are averages from the MTC route data on each route page and may be dated; check live timings in the Chennai One app or with MTC before you travel.
Guindy to Tambaram: the shared trunk
Every through route on this corridor uses the same run of stops after Guindy: St Thomas Mount PO, Meenambakkam (the old airport), Thirusoolam (the national airport), Pallavaram, Chromepet, T.B. Sanatorium and Tambaram. The differences lie in where each bus comes from. 21G starts at Broadway and reaches Guindy via the Marina, Mandaveli, Adyar Gate and Anna University. 18A comes down Anna Salai. 500 starts at T. Nagar, G70 at Vadapalani via Jaffarkhanpet and CIPET, and 70A comes all the way from Avadi along the Inner Ring Road and joins at St Thomas Mount.
| Route | Ends | Length | Average gap | South of Tambaram |
|---|---|---|---|---|
| 21G | Broadway to Tambaram | 33.6 km | 7 min | No |
| 70A | Avadi to Vandalur Zoo | 45.9 km | 13 min | Perungalathur, Vandalur |
| G70 | Vadapalani to Guduvanchery | 33 km | 19 min | Vandalur, Urapakkam, Guduvanchery |
| 118 | Tambaram to Maraimalai Nagar I.E. | 20.6 km | 19 min | Starts here |
| 500 | T. Nagar to Chengalpattu | 46.9 km | 29 min | Through to Chengalpattu |
| 18A | Broadway to Tambaram | 26.4 km | 57 min | No |
Source: MTC route data via Spirit of Chennai route pages, opened 19 October 2026. Gaps are averages and may be dated.
Beyond Tambaram: Vandalur, Guduvanchery, Chengalpattu
From Tambaram the road runs through Irumbuliyur, Perungalathur, Vandalur and Vandalur Zoo. 70A ends at the zoo. G70 and 118 carry on via Urapakkam School and Palakka Company to Guduvanchery, and 118 then turns into Maraimalai Nagar and its industrial estate. Only 500 continues past Maraimalai Nagar through Ford, S.P. Koil and Mahindra City to Chengalpattu old and new bus stands.
It’s often said that you have to change at Tambaram to go further south by city bus.
The figures show Two of the six routes, 500 from T. Nagar and G70 from Vadapalani, run straight through to Guduvanchery, and 500 continues to Chengalpattu, per MTC route data.
Metro, feeders and the 2026 additions
The CMRL station list puts Blue Line stations at Guindy, Alandur, OTA-Nanganallur Road, Meenambakkam and Chennai International Airport, so the bus and metro overlap as far as the airport. From the airport, CMRL’s Metro Connect list names small bus S100 through Pallavaram, Chrompet, MIT and Chitlapakkam to Tambaram East, and S69 through Pammal and Anakaputhur to Kundrathur.
When 130 AC electric buses were flagged off on 25 August 2026, the routes listed for the Alandur depot included MAA1 from Chennai Airport to Kilambakkam, 500P from Pallavaram to Chengalpattu and 70V from Koyambedu to Kilambakkam, DT Next reported. Those three extend the GST corridor’s AC options; their stop lists were not yet on the route pages we checked.
First and last buses
The 21G route page lists the first bus at 5.45 a.m. and the last at 9.25 p.m. from both Broadway and Tambaram, an end-to-end time of 85 to 95 minutes, and both ordinary and express services, with no AC buses on the route. It also warns that midday gaps can stretch to 20 to 30 minutes. The 18A page lists a first bus at 5 a.m. and a last bus around 9.30 p.m. from both ends, with 65 to 80 minutes end to end. The 500 page gives a 5 a.m. first bus from T. Nagar and Chengalpattu but no last bus, so check the app for evening trips.
Length of route 500, T. Nagar to Chengalpattu, the only route in this set that covers GST Road from Guindy to Chengalpattu in one ride.
Quick answers
Which bus goes from Guindy to Tambaram?
21G, 18A, 500 and G70 all stop at Guindy and Tambaram. 21G is the most frequent in MTC route data, averaging about 7 minutes.
Is there a city bus from Chennai to Chengalpattu?
Yes. MTC route 500 runs from T. Nagar to Chengalpattu, 46.9 km, with an average gap of 29 minutes in the route data.
Which bus stops at Chennai airport on GST Road?
Five of the six routes in this guide stop at Thirusoolam National Airport; the exception is 118, which starts at Tambaram.
How do I get from the airport metro to Tambaram East?
CMRL lists feeder small bus S100 from Chennai International Airport metro to Tambaram East (MCC) via Pallavaram and Chrompet.
Information checked against official sources on 19 October 2026. Routes, timings and fares can change; confirm on the linked official pages or in the Chennai One app before travelling.
Sources
- Route 21G: Broadway to Tambaram (MTC route data via Spirit of Chennai route page)
- Route 18A: Broadway to Tambaram (MTC route data via Spirit of Chennai route page)
- Route 70A: Avadi to Vandalur Zoo (MTC route data via Spirit of Chennai route page)
- Route G70: Vadapalani to Guduvanchery (MTC route data via Spirit of Chennai route page)
- Route 500: T. Nagar to Chengalpattu (MTC route data via Spirit of Chennai route page)
- Route 118: Tambaram to Maraimalai Nagar Industrial Estate (MTC route data via Spirit of Chennai route page)
- Chennai Metro Rail: operational lines and stations (CMRL)
- Metro Connect feeder services and MTC small buses (CMRL)
- Metropolitan Transport Corporation, Chennai (Government of Tamil Nadu)
- CM Vijay flags off 130 new AC electric and 120 regular buses in Chennai (DT Next)
- TN launches Chennai One app for travel on public transport with a single QR ticket (PTI via The Week)
