If your train has unscheduled/scheduled halt at PM. Then you can take metro from Palam metro station of Magenta Line metro which is just few meters away to reach following locations -
1. For West Delhi & IGI Airport Terminal-1 => Take direct magenta line metro, fare would be around ₹30 for airport. Shuttle buses are also available to reach other terminals for ₹30. For dwarka, there are many buses to different sectors or you can take auto/cabs.
2. For Gurugram => Best option would be taking passenger trains from here...
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to reach Gurugram railway station specially for old gurugram. You can also take magenta line and change metro to yellow line at hauz khas metro station to reach new gurugram. Fare would be around ₹60 excluding rapid metro fare.
3. For NDLS & NZM => You can board bus route no. 781 or 728A to reach NDLS from palam railway bus stop which located at the flyover just above the station. You can take bus route no. 794 to reach NZM from Manglapuri bus terminal which is at walking distance from here. You can also take bus route RL-77 for NDLS from this terminal.
4. For South Delhi => DTC & DIMTS bus routes 727, 715, 764, 774, 781, etc are available to various locations of south delhi. Fares for non-AC & AC buses are ₹5, ₹10 & ₹15 and ₹10, ₹15, ₹20 & ₹25 respectively depends on the distance you are travelling. You can also take magenta line metro.
5. For Noida => Take magenta line towards Botanical Garden. Train itself terminates at Botanical Garden which is located in Noida, fare would be ₹50. You can also change metro to Blue Line from there or catch auto, cab or bus if you need to go somewhere else in Noida.
6. For Greater Noida => Deboard at Botanical Garden station, from there you can get buses frequently towards pari chowk in greater noida. Fares for AC low floor would be ₹47 & non-AC would be ₹37.
7. For Faridabad => Take Magenta Line & change metro to Violet Line at Kalkaji Mandir station, metro fare from Palam to Old faridabad metro station would be ₹50. Or you can take 774 bus route to reach Badarpur Border from there many options are available to reach Faridabad as well as Ballabhgarh.
Note:- Your luggage size should not exceed 15 kgs and length, width & height of 60 cm, 45 cm & 25 cm respectively. Also note that this tip is not for senior citizens & disabled as they have to walk few distance to reach metro station & manglapuri terminal. It is recommended that they should take cab or auto if they deboard at this station. Magenta line is only available between 6:30 AM (8:00 AM on sundays) to 11 PM. Please reply to me if any correction is needed.