A5758 road

The A5758 road (also known as Broom's Cross Road or the Thornton Bypass) is a 2.2-mile (3.5 km) single-carriageway road in Merseyside, England, constructed during 2014–15 and linking the A565 road in Thornton to Switch Island junction. The road is officially named the A5758 Broom's Cross Road, with Broom's Cross being the site of a medieval wayside cross near Thornton and the road numbering referencing the two motorways the road links to, the M57 and M58 motorway respectively.

Discussions about the need for the road to be constructed date back to the construction of Switch Island junction, with numerous public consultations held throughout the years to ascertain public support and opinion on the need for the road and the alignment it would take. The consultations have produced favourable responses from the majority of respondents, with several different alignment suggestions being proposed over the years.

Sefton Council gave their final approval in September 2013, with construction starting towards the end of the 2013 calendar year. The cost was in the region of £20.4 million, with the UK Government contributing £14.5M towards that and Sefton Council contributing £5.9M. The financial benefits over the 6 years following construction of the road has been estimated to be in the region of £140–200M.

The need for an improved route between Switch Island and the main Southport Road was first identified during the early 1930s. Around that time, workmen "pegged out" a route across farmland near Ince Woods which never materialised. Further proposals were discussed in 1968, during planning for the M57, M58, and M62 motorways. Shortly after the motorways opened, a number of proposals to allow traffic to bypass Thornton and Netherton were developed, given increased road traffic over the years that followed added to the congestion throughout Thornton. The location on where a road would be built was a controversial subject during the 20th century, due to close proximity to Ince Woods and environmental concerns. County planners of the time favoured widening the A565 road.

In 1990, a detailed proposal known as the Blue Route was submitted for planning permission, which would have involved a 4.7-mile (7.6 km) dual carriageway road between Switch Island and the Formby Bypass. This proposal was ultimately rejected by then Secretary of State for Transport in May 1995 despite favourable public consensus, on the grounds it would have negative impact on greenbelt land and be detrimental to conservation areas and protected species.

A Sefton Council environmental statement in 2010 made reference to the traffic congestion that had affected routes around the Thornton area for "many years", as well as the impacts to quality of life and the environment.

In May 2000, a public consultation began which proposed six possible options, with the intention to understand the views and opinions of residents and businesses along the route between Thornton and Switch Island. Following feedback, six options were considered for possible highway construction, those being:

Of all the considered options, Option 5 performed well during the appraisal process and was identified as being the preferred option to pursue by Sefton Council. A further consultation was undertaken in 2003, during which questionnaires were distributed to ascertain resident and business viewpoints on the proposal identified in the 2000 consultation; it determined nearly 80% of respondents agreed for the need of a new road as proposed, with the majority of those questioned strongly agreeing. Of those that did not agree to the preferred option, nearly a third (30%) expressed concerns that the proposal may result in increased congestion, whilst a quarter (25%) expressed a preference for the route to be constructed as a dual carriageway.