|To:||Great Blakenham (TM119504)|
|Length:||5.6 miles (9 km)|
|Met:||A12, A1071, A45|
|Now part of:||B1113|
|Route outline (key)|
Starting on the A12 at Copdock the road headed northwards to cross the A1071 before going through Sproughton and passing to the west of Bramford. Just before reaching Great Blakenham the road split with both forks ending on the A45: one in Great Blakenham; the other to the west of Claydon.
The A1100 been made obsolete by the opening of the A45 (now A14) Ipswich Western Bypass and has been downgraded to become the B1113. The spur to Claydon and the road immediately north of Copdock are unclassified.