Simplify the following text for a Grade 13 native English-speaking person.
Original: The Southeastern Pennsylvania Transportation Authority ( SEPTA ) is a regional municipal authority that operates various forms of public transitâ '' bus , subway and elevated rail , commuter rail , light rail , and electric trolley busâ '' that serve 3.8 million people in and around Philadelphia , Pennsylvania .
Simplified: The Southeastern Pennsylvania Transportation Authority ( SEPTA ) is a agency that is in control of many types of transport , including buses , commuter rail , elevated rail and subways . It operates 13 `` Regional Rail '' services in the Philadelphia , Pennsylvania area .