It is very easy to traverse trinidad by color-coded 'maxi-taxis'. Green for Chaguanas; red ,black and yellow along the stretch from diegomartin to Sangre Grande in the north; brown in the south. Check when on island.
They leave when full and one seat per person with no crowding.
The national bus company has an express service to San Fernando & POS.
Share-taxis, 4-passengers and a driver, are cheap and in good condition. These are the faastest way to get around locally to specific points. Alternately these can be hired privately at a 'bargained price'. They are all in really good condition.
The main routes are the north-south Uriah-Butler higher from POS to Chaguanas. It changes name to here Solomon-Hochoy & runs directly to San Fernando.
Along the northern urban corridor known as the 'east-west' corridor a similar dual carriage way runs from Diego Martin in the west to Arima in the east.
The roads are filled with cars and unless you are a local caught in rush-hour when the 30km commute to POS from Cahguanas can take as much as 2hours, you should miss this event.