Simple Tunnel.lua

function forward()
    while turtle.detect() do
        turtle.dig()
        sleep(0.5)
    end
    flag = turtle.forward()
    while not flag do
        turtle.attack()
        sleep(0.5)
        flag = turtle.forward()
    end
end

function up()
    while turtle.detectUp() do
        turtle.digUp()
        sleep(0.5)
    end
    flag = turtle.up()
    while not flag do
        turtle.attackUp()
        sleep(0.5)
        flag = turtle.up()
    end
end

function down()
    while turtle.detectDown() do
        turtle.digDown()
        sleep(0.5)
    end
    flag = turtle.down()
    while not flag do
        turtle.attackDown()
        sleep(0.5)
        flag = turtle.down()
    end
end

function forward_two()
    forward()
    turtle.select(1)
    turtle.placeDown()
    up()
    up()
    turtle.placeUp()
    forward()
    turtle.placeUp()
    down()
    down()
    turtle.placeDown()
end

i = 10
while i > 0 do
    forward_two()
    i = i-2
end