90 lb Rail Dimensions and Clips

The 90 lb rail is a versatile and widely used profile in North American railway systems, particularly on mainlines, branch lines, and industrial tracks. A thorough understanding of the 90 lb rail dimensions is crucial for engineers, project managers, and maintenance crews involved in track design, construction, and upkeep. This rail, with a nominal weight of 90 pounds per yard, offers a balanced combination of strength, durability, and cost-effectiveness. It is commonly specified by standards from the American Railway Engineering and Maintenance-of-Way Association (AREMA) and the former American Railway Association (ARA), most notably the 90RA or 90 ARA-A profile. This guide provides a detailed technical overview of the 90 lb rail and the various rail clips compatible with its profile.

90 lb Rail Dimensions

The specific geometry of a rail profile dictates its mechanical properties, including its ability to handle loads, resist wear, and maintain stability. The 90 lb rail, specifically the 90RA (ARA-A) section, is engineered for reliability in a variety of service conditions. Its dimensions are carefully calibrated to balance the weight on the rail head with a stable, wide base, all connected by a robust web. This design ensures that the rail can effectively manage both the vertical forces from train axle loads and the lateral forces experienced on curves. Adherence to these precise specifications is fundamental to the safety and interoperability of the rail network.

90RA (ARA-A) Rail Specification Table

The following tables detail the key dimensions and engineering properties of the 90 lb ARA-A rail profile, presented in both metric and imperial units for comprehensive reference.

Dimensional Specifications (Metric)

Dimensional and Mechanical Specifications (Imperial)

The head width of 65.09 mm provides a durable running surface for train wheels, while the overall height of 142.88 mm gives the rail significant vertical stiffness. This stiffness is essential for distributing heavy loads across multiple sleepers, reducing pressure on the ballast and subgrade.

The base width of just over 5 inches creates a stable footing on the tie plate, resisting the tendency of the rail to overturn under lateral forces from the train. The Moment of Inertia and Section Modulus values quantify the rail’s resistance to bending. A higher value indicates greater strength, and the 90 lb rail’s properties make it suitable for tracks carrying substantial freight traffic.

Material composition is another critical element. The 90 lb rail is typically manufactured using high-carbon steel, often to grades like 900A or 1100. This steel provides the necessary hardness to resist wear from wheel contact while retaining enough ductility to prevent brittle fractures from impact loads or in cold weather.

Compatible Rail Clips for 90 lb Rail

A rail is only as secure as its fastening system. Rail clips are the primary component responsible for holding the rail to the sleeper, preventing longitudinal movement and maintaining the correct track gauge. For a versatile rail like the 90 lb profile, which can be found in mainline, industrial, and yard tracks, various types of clips are used depending on the specific application and track conditions. The choice of clip impacts track stability, maintenance requirements, and overall performance.

Bolted and Friction-Fit Rail Clips

In many industrial, yard, and jointed track applications, bolted or friction-fit clips are a common and effective choice for securing 90 lb rail. These clips offer a simple, robust, and rigid fastening solution. They are typically single-piece steel forgings that are either bolted down or welded to a baseplate or steel support structure.

A prime example is the No. 106 clip, which is specifically designed for 90 lb ARA-A rail, among other similar profiles. Another common type is the No. 62 clip. These clips work by tightly clamping the edge of the rail base.

Key Features of Bolted/Friction-Fit Clips:

• Material: High-strength forged steel for maximum durability and clamping force.
• Installation: Can be installed with standard track bolts or hook bolts, or the base component can be welded directly to a steel tie or runway beam. This versatility makes them suitable for a wide range of substructures.
• Application: Excellent for tracks with frequent stops and starts, turnouts, and crane runways where high longitudinal and lateral restraint is required. They are also well-suited for jointed tracks where thermal expansion is managed at the joints rather than through the fastening system.
• Rigidity: These clips provide a very firm connection, which is beneficial for precise track alignment, especially in crane rail systems.

Adjustable Crane Rail Clips

For crane runway applications using 90 lb rail, adjustable clips are often employed. These systems consist of two main components: a lower part that is welded or bolted to the support structure and an upper component that can be adjusted laterally. This design allows for very precise alignment of the rail, which is critical for the smooth operation of overhead cranes.

Many adjustable clips also incorporate an elastomeric “nose”—a block of rubber or a similar polymer that presses directly against the rail web or foot. This feature provides several benefits:

• It allows for controlled longitudinal movement of the rail due to thermal changes.
• It absorbs vibrations and shock from the crane wheels, reducing noise and fatigue on the entire structure.
• It helps absorb the “bow wave” effect, where the rail flexes ahead of the moving wheel, which can reduce stress on the clip’s bolts.

Specifications for Adjustable Clips:

• Lateral Adjustment: Can offer up to 15 mm or more of lateral adjustment, facilitating precise alignment.
• Lateral Capacity: Engineered to handle high side loads, with capacities often exceeding 120 kN.
• Mounting: Available in both weldable and bolted configurations to suit different foundation types.

The selection between a simple friction clip and a more complex adjustable clip depends on the tolerances required for the application. For standard railway sidings, a friction clip is often sufficient. For high-precision crane runways, the alignment benefits of an adjustable clip are indispensable.