Test.lua

function dig()
    while turtle.detect() do
        turtle.dig()
        os.sleep(0.5)
    end
    turtle.forward()
    while turtle.detectDown() or turtle.detectUp() do
        turtle.digDown()
        turtle.digUp()
    end
end

local Digit = 0

term.write  ("Tunnel Length: ")
Digit = read()

for i = 1, Digit do
    dig()
end

turtle.turnRight()
turtle.turnRight()

for i = 1, Digit do
    turtle.forward()
end