The Comber Bypass was built in two phases thirty years apart and connects the Belfast Road to the north west to the Newtownards Road to the north east, and passes round the south side of the town on the line of the former railway line. Phase 1 (mid 1970s) connected the Belfast Road to the Killinchy Road while phase 2 (2003) connected the Killinchy Road to the Newtownards Road. Because of the hilly nature of Comber, the bypass passes over Mill Street and under the A21 Ballygowan Road. A short link road connects Mill Street to a T-junction with the Belfast Road. This sketch map illustrates the current arrangement:

The problem with this is that there is no convenient connection between the A21 Ballygowan Road and the Bypass. Quite a lot of trafic approaches from this direction and must either drive along Railway Street (a residential area) to the T-junction to the north, or else continue to The Square in the centre of town via The Brae or Mill Street (defeating the purpose of a bypass). To make matters worse both The Brae and Mill Street are narrow streets and in places are not wide enough for two vehicles to easily pass each other.

The plan, sometimes referred to as "Phase 3" of the Comber Bypass, would connect the Comber Bypass directly to the Ballygowan Road, by re-aligning Ballygowan Road to the south, starting at the current town limits, and joining the Comber Bypass just west of the existing Killinchy Road roundabout, probably with another roundabout. The land that would be needed for this scheme is largely undeveloped and some of the land is owned by Roads Service. However, Roads Service are not in any hurry to provide this link and currently there are no plans to proceed in the near future.

Progress

31 Aug 2009. The Ards and Down Area Plan 2015 was finally adopted in March 2009, seven years after the draft was released. It reaffirms the intention to preserve land for this scheme: "This road line continues to be protected as a means of permitting traffic on the Ballygowan Road to join the strategic road network (Comber By-pass) and to get to/from more strategic destinations. At present Ballygowan Road traffic has to either use Railway Street or Bridge Street, Newtownards Road and Killinchy Road in order to gain access to the Comber By-pass. It has been protected for a considerable number of years and previous development has been designed to accommodate it. Some land has already been purchased and discussions on other planning applications have taken account of it. It represents the last opportunity to connect the last remaining main route into Comber into the strategic road network."