The tunnel has been extended twice since it was originally built. The Midland Railway's Ripley to Heanor branch was built across the front of the Western portal with a new section of tunnel passing underneath bringing the total length at this time to 3063 yards (2801m). After the tunnel's closure the A38 road was built over the old railway track. The extra width required by the road brought about the introduction of an extra wide, long cylindrical culvert to the Western end of the tunnel bringing the new length to about 3083 yards (2819m).