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Hollow Switch Ties (HST®)

HST® Hollow Switch Tie improves turnout reliability, gauge restraint, and maintenance efficiency using steel ties, composite blue rods, and rotary assist technology. Compatible with virtually any switch machine.

The HST® (Hollow Switch Tie) is an advanced turnout support system consisting of robust, maintenance-free formed steel crossties, high-strength composite Blue Rods, and an optional Rotary Assist system. Designed to improve gauge restraint and facilitate continuous mechanized surfacing through the turnout, HST® provides a durable and reliable solution for modern rail infrastructure.

By relocating switch rods from the crib into the hollow portion of the crosstie, the HST® system allows turnout surfacing operations without removing and reinstalling switch rods. The system also addresses common turnout maintenance challenges, including switch rod insulation failures, gauge maintenance issues, and the performance limitations associated with traditional timber and concrete headblock crossties.

Its non-handed design simplifies installation and inventory management while delivering improved turnout performance, reduced maintenance, greater reliability, fewer trouble calls, and positive gauge control. HST® can be used with virtually any traditional switch machine and is available in configurations optimized for specific turnout applications.

Key Benefits

Improved Gauge Control and Track Stability

  • Improves gauge restraint and positive gauge control.
  • Gauge widening resistance exceeds 40,000 lbs.

Simplified Maintenance and Surfacing

  • Facilitates continuous mechanized surfacing through the turnout.
  • Relocates switch rods into the hollow crosstie, eliminating rod removal and reinstallation during surfacing operations.
  • Reduces common insulation failure points associated with traditional rod assemblies.

Enhanced Reliability and Flexibility

  • Improves switch reliability and reduces maintenance requirements.
  • Non-handed design simplifies installation and inventory management.
  • Compatible with virtually any traditional switch machine.
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Applications

  • The HST® Switch configuration is designed to support reliable switch-point operation while maintaining positive gauge control in one of the most critical areas of the turnout.

    Key Features & Benefits

    • Improved gauge restraint.
    • Positive gauge control.
    • Greater switch reliability.
    • Reduced maintenance requirements.
    • Improved switch life.
    • Facilitates mechanized surfacing through the turnout.

  • The HST® Frog configuration provides enhanced turnout support in the frog area, helping maintain geometry and performance in locations subjected to concentrated wheel loads and repeated impact forces.

    Key Features & Benefits

    • Improved turnout support.
    • Positive gauge control.
    • Enhanced turnout reliability.
    • Reduced maintenance requirements.
    • Improved geometry retention.
    • Facilitates mechanized surfacing through the turnout.

  • The HST® Rotary Assist system is designed to facilitate switch operation in applications requiring additional operating force or multiple throw point locations. The system distributes operating forces throughout the turnout and supports reliable point movement in demanding applications.

    Key Features & Benefits

    • Maximum throw points with Rotary Assist: 4.
    • One switch machine connection with up to three additional assisted locations.
    • Maximum throw force: 4,000 lbs per location.
    • Maximum operating force limited to 8,000 lbs total for all locations.
    • Compatible with traditional switch machine installations.

  • HST® Lite is designed for applications carrying less than 40 MGT annually while maintaining the key advantages of the HST® platform. It provides an economical alternative for lower-tonnage routes while retaining the durability, reliability, and gauge restraint benefits associated with HST® technology.

    Key Features & Benefits

    • Intended for track carrying less than 40 MGT per year.
    • Tie thickness: 3/8" (9.5 mm).
    • Maintains the core benefits of the HST® system.
    • Cost-effective solution for lower-density rail operations.

Universal HST® Design

The Universal HST® represents the next generation of Hollow Switch Tie technology. Building on the proven performance of the HST® system, the Universal HST® was developed to provide greater installation flexibility, simplified maintenance, and improved inventory efficiency while retaining the gauge restraint, reliability, and surfacing advantages of the original design.

Previous generations of HST® required specific configurations based on turnout size, turnout hand, and switch machine location. The Universal HST® introduces a more adaptable approach through a permanent electrically isolated shim plate attached to the formed steel crosstie, allowing switch plates to be changed based on turnout requirements.

Benefits

  • One base unit for multiple turnout configurations.
  • One base unit for multiple turnout configurations.
  • Adaptable to left-hand or right-hand installations.
  • Accommodates field-side or gauge-side switch machine locations.
  • Simplifies inventory management and spare parts requirements.
  • Allows switch plates to be removed and replaced without modifying the insulated crosstie assembly.
  • Easier conversion between turnout configurations.
  • Maintainer-friendly design.

Maintenance and Installation Advantages

Rather than requiring different assemblies for each turnout configuration, Universal HST® utilizes a single adaptable base assembly that can be configured by changing switch plates. This approach simplifies maintenance activities, improves field flexibility, and helps railroads respond more efficiently to changing installation requirements.

  • Blue Rod technology is available for HST® applications and utilizes pre-stressed glass-fiber composite rods engineered to provide exceptional strength, durability, and electrical isolation. The technology has been developed to help improve system reliability while reducing common insulation challenges associated with traditional bolted steel rod assemblies.

    When incorporated into an HST® system, Blue Rod technology can support improved turnout performance, reduced maintenance requirements, and long-term operational reliability.

    Key Advantages

    • Tensile strength of 100,000 PSI.
    • Approximately three times the strength of mild steel rods.
    • Impact strength approximately three times greater than mild steel.
    • Lower thermal expansion than steel.
    • Excellent dielectric properties.
    • Electrical insulation capabilities.
    • Helps eliminate common insulation failure points associated with bolted steel rod assemblies.
    • Reduced maintenance requirements.
    • Long-term durability in railway environments.

    Mechanical Properties

    • Material: Pre-stressed glass-fiber composite.
    • Tensile Strength: 100,000 PSI.
    • Flexural Modulus: 6.0 × 10⁶ PSI.
    • Impact Strength: 49 foot-pounds/inch.
    • Thermal Coefficient of Expansion: 3.0 × 10⁻⁶ inches/inch/°F.
    • Dielectric Strength: >400 volts/mil.

    Blue Rod technology combines high mechanical strength with excellent electrical isolation properties. The material is engineered to provide reliable performance while accommodating turnout movement and operating forces. When utilized in HST® applications, Blue Rods can help support long-term turnout performance while minimizing maintenance requirements.

System Components

The HST® system combines multiple engineered components to deliver superior turnout performance:

  • Formed steel ties manufactured from ASTM A588 steel.
  • Available Blue Rod technology.
  • Rotary Assist assemblies where required.
  • Integrated switch machine mounting capability.
  • Huck pin fasteners for mechanical assembly.

Why Choose HST®?

HST® is more than a turnout tie system. It is a turnout support platform specifically designed to address common turnout maintenance and operational challenges, including exposed switch rods, insulation failure points, gauge maintenance issues, and limitations during mechanized surfacing operations. By integrating structural support, rod management, machine mounting flexibility, and Blue Rod technology into a single system, HST® helps improve turnout reliability while reducing maintenance requirements.

Protected Internal Rod Design

HST® relocates switch rods from the crib into the hollow portion of the crosstie, protecting critical operating components and allowing continuous mechanized surfacing through the turnout without removing and reinstalling switch rods. This design helps reduce maintenance complexity and improve long-term reliability.

Positive Gauge Control

Switch plates attached with permanent Huck fasteners increase gauge widening resistance through the turnout, exceeding 40,000 lbs and helping maintain proper track geometry in critical turnout areas.

Universal HST® Flexibility

The Universal HST® design allows a single base assembly to accommodate multiple turnout sizes, turnout hands, and switch machine locations. This flexibility helps reduce spare inventory requirements, simplify maintenance planning, and minimize delays caused by field installation changes.

Enhanced Reliability

Blue Rod technology helps eliminate common insulation failure points associated with traditional bolted steel rod assemblies while providing excellent mechanical strength, durability, and electrical isolation.

Built for Modern Turnout Maintenance

By combining formed steel crossties, optional Rotary Assist capability, Universal HST® adaptability, and Blue Rod technology, HST® provides a durable solution focused on turnout reliability, maintainability, and operational efficiency.

 

Contact our specialists to discuss your application requirements and determine the right HST® configuration for your network.

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