▁material ▁and ▁finish ▁the ▁initial ▁testing ▁phase ▁of ▁the ▁machine . ▁By ▁March ▁ 1 4 , ▁Ber tha ▁had ▁finished ▁its ▁ ▁bore ▁to ▁a ▁" safe ▁haven " ▁located ▁ahead ▁of ▁the ▁Al ask an ▁Way ▁Vi ad uct ; ▁allowing ▁W SD OT ▁and ▁S TP ▁to ▁prepare ▁for ▁a ▁two - week ▁closure ▁of ▁the ▁vi ad uct ▁in ▁late ▁April ▁as ▁the ▁machine ▁passed ▁under ▁the ▁vulner able ▁structure ▁while ▁closely ▁monitor ed . ▁Following ▁a ▁month ▁of ▁maintenance ▁and ▁ins pe ctions , ▁Ber tha ▁res umed ▁t unn eling ▁on ▁Friday , ▁April ▁ 2 9 , ▁ 2 0 1 6 , ▁and ▁crossed ▁ ▁under ▁the ▁closed ▁vi ad uct ▁in ▁an ▁ 1 1 - day ▁closure ▁in ▁early ▁May ▁that ▁ended ▁earlier ▁than ▁scheduled . ▁ ▁In ▁June ▁ 2 0 1 6 , ▁the ▁tunnel ▁reached ▁its ▁lowest ▁point , ▁ ▁under ▁Mad ison ▁Street ▁in ▁dow nt own . ▁A ▁maintenance ▁stop ▁from ▁June ▁ 2 3 ▁to ▁July ▁ 1 8 ▁was ▁conducted ▁under ▁Spring ▁Street , ▁replacing ▁ 3 3 ▁of ▁the ▁cut ter head ' s ▁teeth . ▁ ▁By ▁September ▁ 3 0 , ▁ 2 0 1 6 , ▁Ber tha ▁had ▁tun ne led ▁, ▁sur pass ing ▁the ▁half way ▁mark ▁of ▁the ▁planned ▁ ▁distance . ▁ ▁the ▁tunnel ▁length ▁reached ▁ 7 0 % ▁completion . ▁ ▁T unnel ▁b oring ▁was ▁completed ▁on ▁April ▁ 4 , ▁ 2 0