The A4042 is a trunk road that runs from Abergavenny to Newport in south Wales. Route Starting at the junction of the A40 and A465 south of Abergavenny, the A4042 travels south towards Little Mill north of Pontypool. This section is a single carriageway and is winding and undulating. From Little Mill onwards the road is dual carriageway, bypassing Pontypool and Cwmbran before crossing the city boundary into Newport. The road has a junction (25A) with the M4 motorway and south from there loses its primary status and becomes an urban road. The first section of which, Heidenheim Drive (named after one of Newport's twin towns), is an elevated roadway through the Crindau district. The road then becomes the Kingsway that passes through Newport city centre, and continues on as Usk Way until its junction with the A48 Southern Distributor Road to the south of Newport. Junctions {| class="wikitable" |- align="center" bgcolor="#00703C" style="color: #ffd200;font-size:120%;" | colspan="3" | A4042 |- align="center" !scope=col| Northbound exits !scope=col| Junction !scope=col| Southbound exits |- align='center' | Merthyr Tydfil, Hereford A465 Abergavenny, Brecon, Monmouth A40 | Ysbytty Fields Roundabout | Start of A4042 |- align='center' | Llanfoist B4269 | Llanellen Junction | Llanfoist B4269 |- align='center' | Usk A472 | Little Mill Junction | Usk, Little Mill A472 |- align='center' | Mamhilad | Mamhilad Roundabout | Mamhilad |- align='center' | New Inn | New Inn Roundabout | New Inn |- align='center' | Pontypool A472 (A4043) | Pontymoile Roundabout | Pontypool A472 (A4043) |- align='center' | Cwmbran A4051 New Inn | Craig-y- Felin | New Inn Cwmbran A4051 |- align='center' | Croesyceiliog | Croesyceiliog Roundabout | Croesyceiliog |- align='center' | Croesyceiliog Caerleon B4236 | Turnpike Roundabout | Caerleon B4236 |- align='center' | Llantarnam Cwmbran | Crown Roundabout | Llantarnam Cwmbran |- align='center' | Cwmbran A4051 | Croes-y-Mwyalch | Cardiff A4051 (M4 (W)) |- align='center' | Start of A4042 | Grove Park | London, Chepstow A4042 (M4 (E)) |- align="center" bgcolor="white" style="color: black;font-size:120%;" style="font-size:120%; border-top: black 2px solid;" | colspan=3 | A4042 |- ! Northbound exits ! Junction / Interchange ! Southbound exits |- align='center' | London, Chepstow A4042 (M4 (E)) Caerleon B4596 | Grove Park | Start of A4042 |- align='center' | Cardiff A4051 (M4 (W)) | Harlequin | Cardiff A4051 (M4 (W)) City Centre |- align='center' | Civic Centre B4591 Exit only | Old Green Interchange | Access only |- align='center' | Cattle market Old Town