Question: Where is the line abandoned by the routes operated by Northern on behalf of Merseytravel?

Context paragraphs:
Air Polonia destinations: List of flight destinations served by Air Polonia.  Between 2001 and 2004 the airline served 3 scheduled destinations in Africa and 25 in Europe.  It also operated various cargo routes on behalf of TNT Airways.  The destinations served were as followed (routes operated for TNT Airways are not included):

Strategic Training Route Complex: The Strategic Training Route Complex is a series of training routes operated by the United States Strategic Command where bomber aircraft are able to train using tactics for low-level flight.  During the Cold War, fourteen routes were operated by the 99th Strategic Weapons Wing.  The current routes are located in Wyoming, South Dakota, North Dakota, and Montana.  One downside to the routes being out west, is that it made it prohibitive for units in the Eastern United States to travel west without expending flight hours.

List of King County Metro bus routes: This is a list of current routes operated by the mass transit agency King County Metro in the Greater Seattle area.  It includes routes directly operated by the agency, routes operated by contractors and routes operated by King County Metro under contract with another agency.  Routes are organized by route number (or letters in the case of RapidRide).  Discontinued routes and former versions of existing routes are not listed.

Rainhill railway station: Rainhill railway station serves the district of Rainhill in Merseyside, England.  It is situated on the electrified northern route of the Liverpool to Manchester Line, forming part of the Liverpool City Line.  The original Liverpool and Manchester Railway which opened in 1830.  The station, and all trains serving it, are operated by Northern on behalf of Merseytravel and are branded as Merseyrail services.

List of bus routes in Brooklyn: The Metropolitan Transportation Authority (MTA) operates a number of bus routes in Brooklyn, New York, United States; one minor route is privately operated under a city franchise.  Many of them are the direct descendants of streetcar lines (see list of streetcar lines in Brooklyn); the ones that started out as bus routes were almost all operated by the Brooklyn Bus Corporation, a subsidiary of the Brooklyn–Manhattan Transit Corporation, until the New York City Board of Transportation took over on June 5, 1940.  Of the 55 local Brooklyn routes operated by the New York City Transit Authority, roughly 35 are the direct descendants of one or more streetcar lines, and most of the others were introduced in full or in part as new bus routes by the 1930s.  Only the eastern section of the B82 (then the B50), the B83, and the B84 were created by New York City Transit from scratch, in 1978, 1966, and 2013, respectively.

List of NJ Transit bus routes (700–799): New Jersey Transit operates the following routes within Passaic and Bergen counties.  All routes are exact fare lines.  Only routes operated directly from New Jersey Transit's Northern Division operate on Sundays.

Utica and Mohawk Valley Railway: The Utica and Mohawk Valley Railway was the result of the unification of all city and suburban streetcar lines serving Utica, New York, on November 27, 1901.  The railway operated city streetcar service (with the acquisition of the Rome City Street Railroad in 1907) as well as a double-track interurban railway between Rome and Little Falls via Utica.  The Utica and Mohawk Valley Railway was merged into New York State Railways in 1912.  At its peak, the Utica Lines consisted of 17 transit routes operated with more than 100 cars.  The line ceased operation in 1933, except for the section between Utica and Whitesboro that survived until 1938.  The last city streetcars operated on May 31, 1941.  The remaining transit routes were operated with buses and the franchise would be reorganized as the Utica Transit Corporation in 1948.

Liverpool–Manchester lines: There were once four direct railway routes between Liverpool and Manchester in the North West of England.  There are now only two remaining direct railway routes between the two cities.  One line, the now northern route, is fully electric and the other, the southern route, is a diesel only line.  A third line which is further north has been split with the western section electric and the eastern section diesel operation, requiring a passenger change between the two cities.  The fourth route, the most southerly, is largely abandoned east of Warrington with the remaining section mostly catering for freight trains.  The remaining two direct routes are:

Route 82 (MTA Maryland LocalLink): Route 82, also known as the Mondawmin Shuttle Bug or Mondawmin Shuttle, is one of two neighborhood shuttle routes operated by the Maryland Transit Administration in Baltimore.  It was the second and is so far the final in the series of shuttle bus routes to be introduced by MTA in the 2000s.  The route serves Baltimore City Community College, Coppin State College, and various nearby streets, some served by regular bus routes, and some not.  But the full route is within a close walk of one or more other MTA bus routes.  The route operates at 25-minute intervals.

City Line (Merseyrail): The City Line is the name given to local rail routes out of Liverpool Lime Street railway station.  It appears on maps of the Merseyrail network as red, and covers the Liverpool–Wigan line as well as the two routes of the Liverpool–Manchester lines.  Although it is branded under the Merseyrail name, the routes are operated by Northern on behalf of Merseytravel rather than by the Merseyrail franchise.

Supporting paragraphs: City Line (Merseyrail) Liverpool–Manchester lines
Answer: east of Warrington