Switch Island [1][2] is a road junction south of Maghull and near Aintree in Merseyside, England on the Liverpool rural-urban fringe. The junction is at the western terminus of both the M57 and M58 motorways, which converge on the A59 trunk road, the north-south route from Liverpool. The junction is also the terminus of the A5036, a road which serves the Port of Liverpool.
Original plans for the two motorways involved them merging at this junction and continuing west, while the A59 continued uninterrupted under (or over) the roundabout, with slip roads to and from the junction. These plans were never completed and instead all four roads converged at the same level on the single roundabout. To complicate matters, the through route of the dual carriageway is not the A59 south to the A59 north, but from the A5036 south to the A59 north. Effectively, this results in two motorways and the port road feeding onto the A59 through route.
The junction carries 80,000 vehicles a day, and improvements are a priority for England's Highways Agency.
In September 2005, roadworks commenced for the improvement of the junction by the Highways Agency. These roadworks were intended to last 7 months during which long delays were usual. The overall aim was to ensure the junction is able to withstand the predicted road traffic increase for the next decade. The roadworks were completed in Spring 2006, and has resulted in an entirely new layout for the junction, removing the roundabout. Only very few vehicles now have to enter the roundabout section, instead using the roads which pass through the centre of it. Even those who must enter the roundabout cannot make a full revolution due to this new layout, with a short stretch of the roundabout now not in use. This western-most piece of road used to form part of the A59, leading vehicles north from Aintree towards Maghull, passing the entry slips for the M57 and M58. This section is no longer open to general traffic but is the site of an inspection area and weighbridge, operated by the Vehicle Inspectorate.