New Interlocking on LIRR Expansion Project Will Help Reduce Train Cancellations & Delays

Nassau Interlocking Completed 02-20-20

You may have heard the term ‘interlocking’ before – perhaps when we reference Harold Interlocking in Queens, the busiest railroad junction in the country. You might not even notice it, but it’s there. And it’s important. But what exactly is an interlocking, and why should you care about it? I’m glad you asked.

An interlocking is a series of switches that enable trains to move from one track to another. Now, why did we need to build an entirely new interlocking? With a new third track being installed, interlockings are needed to enable trains to move to and from the new track to the existing two tracks.

With the LIRR Expansion Project, we’re adding an entirely new track (a third one!) between Floral Park and Hicksville, and we are upgrading the current infrastructure to be able to handle added train capacity, reduce service interruptions and ensure fluid movement of trains between the existing two tracks, as well as the future third one.

In just five months, teams from the Long Island Rail Road and MTA’s Construction and Development installed a total of six switches that will make up the new interlocking to the west of the Mineola Station. Crews are now focused on installing miles of new fiber optic communication lines, power lines, signals and other components required to make the interlocking functional. It is anticipated this new interlocking will be commissioned and become operational (or “cut over”, change from the older system to the new) in January 2021. Once operational, an existing and aging interlocking currently positioned between the New Hyde Park and Merillon Avenue stations will be taken out of service and removed.

Nassau Interlocking Completed 02-20-20

Under the LIRR Forward initiative, to date the LIRR has upgraded 23 switches. Nassau 1 is one of the most highly trafficked areas, where more than 200 trains traverse each day. These switch upgrades, among many other Forward initiatives, have resulted in fewer cancellations, fewer short trains and fewer delayed trains. This interlocking will provide the needed flexibility and reliability through this area when the third track is complete and in use, scheduled for completion in 2022.

About the LIRR Expansion Project

The construction of a third track from Floral Park to Hicksville will reduce train congestion and delays and enable true bi-directional service during peak hours with a more reliable rail network. This transformative work includes several related projects, including the construction of parking garages and accessibility improvements, retaining walls, improvements to rail bridges and the removal of eight street-level grade crossings. Construction is being managed to minimize the impact on daily routines, with extensive mitigation and public outreach efforts in local communities. For more information please visit the LIRR Expansion Project Floral Park to Hicksville project page on