The Massachusetts Port Authority Board approved a partial project budget of $4 million to enhance high occupancy vehicle (HOV) use at Boston Logan International Airport and improve customer service with dynamic signage announcing next bus arrival times and re-aligning terminal curb usage to maximize efficiency.

A new Rental Car Center will start operating this fall with a unified bus system that will replace more than 90 rental car company buses and Massport shuttle buses with 28 new 60-foot articulated buses.

A key element of the partial budget of $4 million approved by the board is the fabrication and installation of dynamic messaging signs that provide real-time HOV information to passengers about buses that will take passengers to the Airport Blue Line T Station, the Rental Car Center and the Logan Express bus system to four suburban parking lots.

Last year, Massport, working with the Massachusetts Bay Transportation Authority, installed countdown signs for the Silver Line at all terminals.

The program will include new wayfinding signs directing passengers to HOV ground transportation and enhanced curb allocations for HOV at the arrivals level of all four terminals in time for the opening of the Rental Car Center.

Massport’s promotion of HOV use includes making trips on the Silver Line from the airport to downtown free; promoting the use of Logan Express from the suburban sites in Braintree, Framingham, Woburn and Peabody, by lowering parking and bus fare at peak times, and increasing the daily parking rate at Logan’s Central Parking garage last year from $24 a day to $27 a day.