Build me a brick road!
V, 20 bytes

123i\  \__ò70|lé
4x


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As usual, here is a hexdump:

0000000: 3132 3369 5c20 205c 5f5f 1bf2 3730 7c6c  123i\  \__..70|l
0000010: e90a 3478                                ..4x


Explanation:

123                     " 123 times:
   i                    " Insert the following:
    \  \__              " '\  \__'
          &lt;esc&gt;         " Return to normal mode
               ò        " Recursively:
                70|     "   Move to the 70th column
                   l    "   Move one char over
                    é   "   Insert a single newline
4x                      "   Delete 4 characters