county          tunnel      type length (imperial) date of opening
0  londonderry      castlerock      rail            668 yd     1845 - 1853
1  londonderry        downhill      rail            307 yd     1845 - 1846
2       armagh       lissummon      rail           1759 yd     early 1860s
3         down  binnian tunnel  aqueduct         2.5 miles     1948 - 1952
4       antrim       whitehead      rail            145 yd     1862 - 1994
5       tyrone       dungannon      rail            800 yd            1862

Table as JSON:
{"county":{"0":"londonderry","1":"londonderry","2":"armagh","3":"down","4":"antrim","5":"tyrone"},"tunnel":{"0":"castlerock","1":"downhill","2":"lissummon","3":"binnian tunnel","4":"whitehead","5":"dungannon"},"type":{"0":"rail","1":"rail","2":"rail","3":"aqueduct","4":"rail","5":"rail"},"length (imperial)":{"0":"668 yd","1":"307 yd","2":"1759 yd","3":"2.5 miles","4":"145 yd","5":"800 yd"},"date of opening":{"0":"1845 - 1853","1":"1845 - 1846","2":"early 1860s","3":"1948 - 1952","4":"1862 - 1994","5":"1862"}}