The tunnels were only temporarily repaired following a fire in 2011 and are now also undergoing essential drainage, carriageway, lighting, mechanical and electrical improvements.
Cafodd y twneli eu trwsio dros dro yn dilyn tân yn 2011 ac maent bellach yn cael eu gwella o ran draenio hanfodol, gwella’r ffordd, y goleuo a gwelliannau mecanyddol a thrydanol.