Project Overview Union Switch & Signal Inc. (US&S®) provided the signaling system for
a 7.5-mile extension to the Sacramento Regional Transit District’s (SRTD) light
rail system. The scope of the work included three microprocessor-based
interlockings, 42 AC track circuits, two switch machines (free issued), 14
highway crossings, and a TWC system (free issued).
The SRTD Folsom Corridor light rail extension project featured a mix of
US&S’s leading solid-state and electromechanical products. This project
encompassed the district’s 7.5-mile, four-station extension to the existing
SRTD light rail system in Sacramento. Approximately 2 miles of the extension
are double-track, which converges to single-track near Market Place Lane.
US&S served as a signaling subcontractor on the project and was responsible
for designing, manufacturing, delivering, and testing a new wayside/highway
crossing signaling system for the extension.
The centerpiece of this project is US&S’s MicroLok® II Vital/Non-vital
Controller, which was installed at two interlockings to manage switch machines,
signals, and track circuits as well as various non-vital functions such as
Local Control Panel (LCP) inputs and outputs. A third, existing interlocking
controller was integrated into the overall system by US&S engineers. The
MicroLok II units control several US&S M-23A electric switch machines
(acquired separately by SRTD) and long-life LED style wayside signals. US&S
100 Hz Power Frequency (PF) track circuits, featuring service-proven PV-250
Vane Relays, were deployed on both the interlocking and mainline tracks to
provide precise train detection indications to the interlocking
controllers.
To enable SRTD vehicle operators to clear routes and proceed through highway
crossing zones, US&S also integrated its Train-To-Wayside Communications
(TWC) electronics and antennas along the wayside. The TWC equipment permits
train operator data to be passed to the wayside while the train is in
motion.
US&S’s Model-95 Highway Crossing Gate Mechanisms and LED-based HC-120B
Flashing Light Assemblies were also deployed along the Folsom extension to
ensure safe interaction of SRTD trains and motor vehicle traffic. Additional
MicroLok II units were deployed to operate 14 crossings, which use solid-state
crossing controllers as the interface between the MicroLok II units and the
crossing gate equipment. US&S Audio Frequency Overlay (AFO-IIC) track
circuits were installed to provide train detection on the approaches to the
crossings.
Key Points
• This was a project for a 7.5-mile / four-station extension to the
existing light rail system in Sacramento. The signaling scope of work was to
design, furnish, and test a new microprocessor -based signal system.
• US&S served as the subcontractor to Mass Electric Construction Co.
(electrical installation) and Kiewit Corp. (general contractor).
• US&S’s scope included:
- 3 – MicroLok II Interlockings
- 2 – M-23 Switch Machines (free issued)
- 42 – AC Track Circuits
- 14 – Highway Crossings
- 1 – Lot of TWC System (free issued)
