|Location Map ( geo)|
|Distance:||22.5 miles (36.2 km)|
|Met:||A36, A35, A31, A341, A342|
|Now part of:||A3057, B3398|
|Route outline (key)|
The B3042 was originally allocated to the road between Southampton and Andover via Romsey and Stocksbridge. The road never actually reached Andover: it ended on the then-A342 (now B3420) near Goodworth Clatford.
The B3042 was upgraded to the A3057 not long after road numbering was introduced, probably by 1st April, 1925. Apart from bypasses in Romsey (where the B3398 follows the old route of the B3042) and Stocksbridge, it is unchanged since then.