 Portions of the Brookville tunnel were lined with brick for added strength , with the brickwork originally contracted to Joseph <unk> , a local brickmaker . Because of the poor quality of <unk> 's bricks , Crozet decided to use these bricks on the Greenwood Tunnel to the east , which was a stronger bore than Brookville . Crozet estimated in 1854 that the total number of bricks required for the entire tunnel would be upwards of 750 @,@ 000 . After examining the offers of multiple brickmakers , the Virginia Board of Public Works contracted Robert Harris to provide the bricks for the Brookville Tunnel . The resulting arch was between 3 – 4 feet ( 0 @.@ 9 – 1 @.@ 2 m ) in thickness over the entire length of the tunnel , and formed an opening approximately 20 feet ( 6 @.@ 1 m ) high and , at the extreme , 15 feet ( 4 @.@ 6 m ) wide . 
