In modern railway infrastructure, maintaining the longitudinal stability of the track is critical to ensuring operational safety and reducing maintenance costs. Among the standard track configurations in North America and internationally, the 115RE rail paired with compatible 115 lb rail anchors represents a widely adopted standard for medium-to-heavy-haul lines, transit networks, and industrial spur tracks.
This technical article discusses the dimensional relationship between 115RE rail and 115 lb rail anchors, their operational functions, classification under AREMA guidelines, and installation considerations.
1. Dimensions and Specifications of 115RE Rail
The "115RE" designation denotes a specific rail section standardized by the American Railway Engineering and Maintenance-of-Way Association (AREMA). The "115" refers to its nominal weight of 115 pounds per yard (approximately 56.9 kg/m).
To ensure a rail anchor functions as intended, its manufacturing tolerances must match the base profile of the rail. Below are the standard engineering dimensions of the 115RE rail section:
| Parameter | Standard Measurement (Imperial) | Standard Measurement (Metric) |
|---|---|---|
| Nominal Weight | 114.7 lbs/yd | 56.9 kg/m |
| Rail Height | 6-5/8 inches | 168.28 mm |
| Base Width (Foot) | 5-1/2 inches | 139.70 mm |
| Head Width | 2-11/16 inches | 68.26 mm |
| Web Thickness | 5/8 inches | 15.88 mm |
Because rail anchors are clamped directly to the base of the rail, the Base Width of 5-1/2 inches (139.70 mm) is the critical dimension determining the design and fit of a 115lb rail anchor.
2. The Engineering Function of Rail Anchors
Rail anchors are single-piece spring steel fasteners applied to the underside of the rail base. They are designed to sit tightly against the sides of the track ties (sleepers) or tie plates. Their primary functions include:
- Controlling Rail Creep: Longitudinal movement of the rail-known as "creep"-is caused by the tractive effort of locomotives, braking forces of trains, and thermal expansion or contraction. Anchors transfer these longitudinal forces from the rail into the ties and ballast bed.
- Maintaining Joint Gaps: In jointed tracks, rail anchors help maintain uniform expansion gaps between rail ends, preventing joint damage and track buckling.
- Securing Continuous Welded Rail (CWR): In CWR systems, temperature variations introduce significant internal stresses. Anchors, along with the ballast profile, constrain the rail to prevent lateral buckling in hot weather and pull-aparts in cold weather.
3. Types of 115lb Rail Anchors
Industrial applications typically utilize two primary designs of rail anchors for 115lb rail systems. Both are manufactured from high-carbon or alloy spring steels and heat-treated to ensure consistent holding power.
A. Drive-On Anchors (Fair Style)
Often referred to as the "Improved Fair" or drive-on style, this anchor features a heavy, jaw-like design. It is installed by placing one end over the rail base and driving the other end onto the opposite side of the base using a maul or an automated applicator machine. The design provides a broad bearing area against the tie plate and tie face.
B. Spring-Type Anchors (Unit/Channeloc Style)
Spring-type anchors (such as the Unit or Channeloc designs) utilize a resilient, spring-action loop. They are applied under the rail base and snapped into place. The spring tension provides two-way contact, gripping the rail base securely. These anchors generally accommodate slight variations in rail base thickness due to wear.
| Name | Rail Anchors | ||
| Type | Used for 50Kg, 85Kg,90/91LB, 115RE /136RE ,UIC54 & UIC60 rail | ||
| Or the type by customers' drawings | |||
| Material | 60Si2MnA | 45# | QT500-7 |
| Chemical composition (%) | C:0.56-0.64, Mn:0.60-0.90, Si:1.60-2.00, Cr:≤0.35, P:≤0.03, S:≤0.03 | C:0.42-0.50, Mn:0.50-0.80, Si:0.17-0.37, Cr:≤0.25, P:≤0.035, S:≤0.035 | C:3.60-3.80, Mn:≤0.6, Si:2.50-2.90, P:≤0.08, S:≤0.025 |
| Surface | plain (oiled),color painting | ||
4. AREMA Standards and Performance Criteria
According to the AREMA Manual for Railway Engineering (Chapter 4: Rail), high-quality rail anchors must meet stringent mechanical performance criteria to ensure safety under load:
- Slip Resistance: A standard newly applied rail anchor is typically expected to withstand a minimum longitudinal force before slipping along the rail base.
Fracture Resistance: The steel must possess sufficient ductility and hardness (often specified within a certain Brinell or Rockwell C hardness range) to prevent cracking during installation or under extreme cold temperatures.
Reusability: Rail anchors are designed to retain a significant percentage of their original holding force when removed and reapplied during maintenance cycles, provided they are not over-stretched.
5. Application and Installation Best Practices
The efficiency of a 115lb rail anchor system relies heavily on correct installation patterns and techniques:
- Full Bearing: The anchor must be installed so that its vertical face rests tightly against the tie or tie plate. Gaps between the anchor and the tie reduce its effectiveness, allowing the rail to move before the anchor engages.
- Symmetrical Anchoring: To control movement in both directions, anchors are typically installed in pairs on opposite sides of the same tie (referred to as "box anchoring").
- Anchoring Patterns: In jointed tracks, standard practices often dictate box anchoring a set number of ties per rail length (e.g., 8 to 16 ties per 39-foot rail), depending on traffic density and grade. Continuous Welded Rail (CWR) generally requires more comprehensive anchoring patterns, sometimes anchoring every tie or every second tie near critical areas like turnouts and bridge approaches.
Frequently Asked Questions (FAQ)
Q1: Can a 115lb rail anchor be used on a 136RE rail section?
No. A standard 136RE rail has a base width of 6 inches (152.4 mm), whereas a 115RE rail has a base width of 5-1/2 inches (139.7 mm). A 115lb rail anchor will not fit a 136lb rail base. Attempting to force-fit incompatible anchors can cause component damage or failure of the fastening system.
Q2: What is "box anchoring" and why is it used?
Box anchoring is the practice of installing two rail anchors on the same tie-one on each side of the tie on the same rail. This prevents the rail from moving in either direction (both forward and backward). It provides two-way longitudinal restraint against thermal expansion and bidirectional traffic.
Q3: How do temperature changes affect the performance of 115lb rail anchors?
Temperature swings cause rails to expand in the summer and contract in the winter. Without adequate and properly fitted rail anchors, these forces can lead to track buckling (sun kinks) or rail pull-aparts. The anchors transfer these thermal forces through the ties and into the ballast, where the resistance of the ballast bed stabilizes the track structure.
Q4: Are drive-on anchors better than spring-type anchors for 115RE rails?
Both styles have proven effective when manufactured to AREMA standards. Drive-on anchors offer a large, solid contact area against the tie and are highly resistant to impact damage. Spring-type anchors are often favored for their resilience and ease of installation in certain automated maintenance setups.