If you're heading to Brechfa or Abergorlech in the next couple of months be aware that there will be traffic restrictions and some road closures, especially during week days.
Dwr Cymru are laying a new water main along the B4310 between Brechfa and Abergorlech starting Monday 20th June for about 10 weeks.
Traffic lights will be in operation but when the works reach pinch points on the route the road will be closed between 9am and 4pm.
Likely pinch points are the Gwernogle turn between Brechfa and Nantyffin, Nantyffin itself and Pistyll Gwyn between Nantyffin and Abergorlech. The longest period of this restriction is likely to be at Nantyffin.
The Forestry Commission have announced that Derwen and Raven trails (out of Byrgwm car park) will be 'closed' during this period, presumably to reduce the amount of traffic in the area - link
Hope this helps, I'll post more information as and when it becomes available.