   the a38(m), also known as the aston expressway, is a motorway in birmingham, england. it is  long and was opened on 24 may 1972.the motorway archive a38(m) â dates it forms part of the much longer a38 route. it is extremely unusual among uk motorways, as it consists of seven lanes with no central reservation, and operates a tidal flow system in an attempt to minimise congestion. due to the nature of the road, the speed limit is reduced to 50&nbsp;mph (80&nbsp;km/h), though there are no permanent speed cameras. when construction work of the motorway began in the late 1960s, many late 19th-century and early 20th-century houses in the aston area had to be demolished to make way for the new route. ==route==  a38(m) runs from the a5127 through gravelly hill interchange where the a38 joins and then shortly after traffic from the m6 motorway also joins. it then enters a tidal flow section. the road is on a viaduct as it passes through aston; this section cuts through the grounds of aston hall.the motorway archive â a38(m) the road passes through its first junction after . it enters a cutting before reaching the second junction, where the tidal flow ends as does the motorway. the motorway is curved in aston to avoid an ansells brewery. the motorway was also crossed by a vinegar pipeline, carrying the condiment from one part of the since-demolished hp sauce factory to the other. ==tidal flow== the expressway was the first road in the united kingdom to introduce tidal flow to allow better management of traffic. lane use is controlled by means of electronic overhead signs, with one lane always closed to create a buffer between the two directions of travel â there is no central reservation. in the morning, four of the seven lanes are designated for use by traffic heading toward birmingham city centre, and two lanes for traffic out of the city. in the evening rush hour, this pattern is reversed and four lanes are made available to outbound traffic and two lanes towards the city centre. at all other times, the road runs with three lanes in each direction. motorcycles are banned from the red-surfaced central lane, which conta
Motorways_in_England Roads_in_the_West_Midlands_(county) Roads_with_a_reversible_lane Transport_in_Birmingham,_West_Midlands