A4109 road

{{Short description|Road in south Wales}}

{{refimprove|date=January 2024}}

{{Use dmy dates|date=January 2024}}

{{Use British English|date=February 2013}}

{{Infobox road

|country=WLS

|type=A

|route=4109

|header_type=minor

|length_mi=

|direction_a= Southwest

|terminus_a = Aberdulais

|direction_b= Northeast

|terminus_b = Glynneath

|junction = {{jct|country=GBR|A|465|name1= }}
{{jct|country=GBR|A|4230|name1= }}
{{jct|country=GBR|A|4221|name1= }}
{{jct|country=GBR|A|465|name1= }}

|destinations=

}}

The A4109 road, known as the Inter Valley Road,[https://democracy.npt.gov.uk/documents/s93599/MR%20DWG%20HAMP%202023-2026%20App%20A%20Final.pdf Highways Asset Management Plan 2023-26] npt.gov.uk page 44 links Aberdulais with Glynneath in Neath Port Talbot county borough, Wales.

The route begins in Aberdulais at the junction with the A4230 and A465 roads; it diverges northwards away from the A465 up the Dulais Valley and crosses through the settlements of Crynant, Ynysfforch, Seven Sisters, Onllwyn, Dyffryn Cellwen and Banwen where it has a junction with the A4221. The road then continues in a southeasterly direction along the Inter Valley Road to Glynneath where it again connects with the A465.