Shankar stays in Vashi in Navi Mumbai and getting to the city takes him a good amount of time. He gets a call from the veteran lyricist usually when he is crossing the Vashi bridge, which is always a traffic bottleneck.
Gulzar and Shankar have their brainstorming sessions over the phone while Shankar's chauffeur maneouvres the traffic snarls. By the time the composer reaches Mumbai, there is already a tune in his head ready to be hummed to Gulzar.