Editing Cobble Hill Tunnel (section)

== Construction and operation ==
Originally built as an [[Cut (earthworks)|open cut]], construction began in May 1844, and opened for use on December 3, 1844, but was not completely finished until mid-1845. It was built mainly to satisfy public demand for creation of a [[Grade separation|grade-separated]] [[Right-of-way (railroad)|right of way]] for the [[Brooklyn and Jamaica Railroad]] (later Long Island Rail Road) on its way to the [[South Ferry, Brooklyn|South Ferry]] at the foot of Atlantic Street (later Atlantic Avenue), where passengers could catch ferries to [[Manhattan]].<ref name="BHRA">{{cite web|url=http://www.brooklynrail.net/images/aa_tunnel/new_research/oct_09/events_leading_to_tunnel_creation.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.brooklynrail.net/images/aa_tunnel/new_research/oct_09/events_leading_to_tunnel_creation.pdf |archive-date=2022-10-09 |url-status=live|title=Events That Led to the Creation of the Atlantic Avenue Tunnel|publisher=Brooklyn Historic Railway Association|access-date=October 29, 2009}}</ref> The construction of the cut also lowered the LIRR's grade through [[Cobble Hill, Brooklyn|Cobble Hill]]. Around five years after opening the cut was roofed over, converting it into a tunnel. As originally built, the cut was {{convert|21|ft|m}} wide and {{convert|2517|ft|m}} long. Once roofed over, the interior height of the newly created tunnel was {{convert|17|ft|m}}.

In exchange for building the cut, the [[City of Brooklyn]] granted the B&J permission to operate its steam locomotives on Atlantic Street west of Fifth Avenue (then Parmentier's Garden/Gowanus Lane), all the way to Brooklyn's South Ferry (the present location of Brooklyn's Pier 7). Prior to the cut being built, the LIRR's western terminus was Atlantic Street at Clinton Street. Train cars were hauled by teams of horses along Atlantic Street from Clinton Street to Parmentier's Garden, where steam locomotives were attached. While the cut was being built, the railroad operated to a temporary terminal at Pacific Street and Henry Street.

The Cobble Hill Tunnel was part of the first rail link between New York City and [[Boston|Boston, Massachusetts]]. The railroad connected [[Lower Manhattan]] via the South Ferry to [[Greenport, Suffolk County, New York|Greenport]] on the [[North Fork, Suffolk County, New York|North Fork]] of [[Long Island]]; a ferry connected Greenport to [[Stonington, Connecticut]], where a rail link continued to Boston. This avoided some difficult construction of bridges over the rivers of southern [[Connecticut]]. In 1848, the [[New York and New Haven Railroad]] Line was completed through Connecticut, providing a direct, faster rail connection from New York City to Boston. The Cobble Hill Tunnel and the Long Island Railroad remained the primary means of access to most of central Long Island from Manhattan and New York City.

The ends of the tunnel were sealed in the fall of 1861. The similar [[Murray Hill Tunnel]] on the [[New York and Harlem Railroad]] was built as an open cut around 1836, roofed over around the 1850s, and is now in use for automobile traffic.