[4] It is only 19.5 kilometres (12.1 mi)[5] long and has very few exits, which work mainly to minimize traffic in the congested Carolina area of PR-3.

[2] The highway is called the Roberto Sánchez Vilella Expressway, which is also the name given to the much larger PR-2 freeway segment from Hormigueros to Ponce.

[citation needed] PR-66 is very close to the El Yunque National Forest and at the start of construction there were problems between developers and environmental activists.

[7] The expressway was planned to be extended to Fajardo but due to the close presence of the forest reserve, it was accorded to be extended to Río Grande and connect to PR-3 which has several exits between that municipality and Fajardo.

[8][9] The short expressway is very expensive in terms of toll fees and many people still go through PR-3 as a consequence.