Starting on the A6078 Blackburn ring road the A6177 headed out of town along Haslingden Road past the hospital to reach the M65 at J5. The road then continued to the east along Grane Road along the Haslingden Grane valley. It crossed the A56 at a south-facing GSJ before continuing into Haslingden itself where it ended on the A680.
In 2005, following a massive campaign to remove HGVs from the route, a 7.5 tonne weight limit was introduced to the road, following on from the 50mph speed limit in 2003. This also caused the relevant highway authorities to get their acts together and eliminate the duplicate number, resulting in a rebirth of the B6232 (the original number of the entire road) and the introduction of the A6077, which only took over that part of the A6177 west of the M65.
Despite heavy congestion and a substandard alignment, this route can still be quicker between the A56 and M65.