 The Pentwyn Link Road ( Welsh : Ffordd Gyswllt Pentwyn ) , which is also known as the North Pentwyn Link Road , runs from the Pontprennau Interchange ( 51 @.@ <unk> ° N 3 @.@ <unk> ° W ﻿ / 51 @.@ <unk> ; <unk> ﻿ ( <unk> Interchange ) ) on the A48 and the Pentwyn Interchange ( 51 @.@ <unk> ° N 3 @.@ <unk> ° W ﻿ / 51 @.@ <unk> ; <unk> ﻿ ( Pentwyn Interchange ( M4 <unk> ) ) ) on the M4 ( junction 30 ) . It is 1 @.@ 61 km ( 1 @.@ 00 mi ) in length and was opened by John <unk> MP , the Secretary of State for Wales on 20 June , 1994 . It provides a link between the Eastern Avenue ( A48 ) and the M4 so that westbound traffic from the east of the city can get onto the M4 without having to go through the city , via the A48 and <unk> . In addition it also provides access to the community of Pontprennau to the national road network . This link was financed by private developers as part of a large scale housing development at Pontprennau . 
