along with sections of the m5 and m6, the southern sections of the m42 form the birmingham outer ring road motorway around birmingham. much like the m25 around london, and the m60 around manchester, there are areas where this orbital system does not work well. one such point is junction 3a, the link between the m42 and the m40, where traffic is often heavy in the rush hour. the intersection between the m42 and m6 is often very busy too, especially when travelling along the m6.