Ko te Tunnel Formwork he momo momo hangahanga, e whakakotahi ana i te ahua o te pakitara maka-i-waahi me te papa o te papa maka-i-wahi i runga i te hanga o te hanga puka nui, kia pai ai te tautoko i te pukamahi kotahi, herea. kotahi te pae rino, katahi ano ka ringihia te pakitara me te hanga puka ki te ahua kotahi i te wa kotahi. Na te ahua ano o tenei ahua he rite ki te kauhanga tapawha, ka kiia ko te tunnel formwork.