<googlemap lat="51.527596" lon="-2.452869"> 51.5206, -2.459092, Frog Lane 51.532775, -2.451754, Frog Lane Colliery 51.535605, -2.448449, Mayshill Colliery 51.536619, -2.446046, Nibley Colliery </googlemap>
I have no idea if this track is part of Frog Lane. The maps show the lane starting at Frog Lane Farm, and the section of old trackbed beyond the farm seems to share the name at least part way, but this section of track is unnamed on every map I have.
There are two railways here. The main Bristol & South Wales to London (via Parkway) mainline, and an old colliery line that served Frog Lane Pit. The colliery railway went under the mainline at 90° and joined the Midland mainline at Westerleigh Sidings. There was also a spur from the colliery railway to Coalpit Heath station.