48″ Inlet Frame and Grate with Curb

The Amercast 48″ Inlet Frame and Grate with Curb is a heavy-duty cast iron curb inlet assembly engineered to efficiently capture stormwater runoff at roadway edges, parking facilities, municipal streets, commercial developments, industrial sites, and transportation infrastructure projects. Designed for both EPA 6-inch and 8-inch curb configurations, this combination frame and grate system directs surface water into underground drainage networks while helping reduce ponding, roadway flooding, and erosion. The assembly features a 48-inch overall inlet length, 42-inch grate opening, integrated curb section, and multiple grate styles to accommodate varying hydraulic and traffic requirements.

Unlike standard catch basin grates that collect water vertically from pavement surfaces alone, curb inlet structures intercept flow directly from the gutter line where runoff naturally concentrates. This improves hydraulic efficiency and enhances stormwater collection performance during heavy rainfall events. Similar curb inlet systems are widely utilized throughout municipal drainage networks because they maximize flow interception while maintaining roadway safety.

Manufactured from gray cast iron and designed for heavy-duty service, the 48″ curb inlet assembly provides long-term durability in demanding traffic environments. Available with Oval Hole, Bicycle Safe, and Streamflow grate patterns, the system can be specified to meet local agency requirements, pedestrian safety standards, and drainage design criteria.

Product Features

• Heavy-duty cast iron construction
• 48″ curb inlet assembly
• Available for 6″ and 8″ curb installations
• Large drainage intake area
• Integrated curb throat design
• Suitable for municipal roadway applications
• Highway-rated casting design
• Multiple grate styles available
• Oval Hole grate option
• Bicycle Safe grate option
• Streamflow grate option
• Corrosion-resistant cast iron
• Reinforced frame construction
• Long service life
• Compatible with storm drainage structures

Typical Applications

The 48″ Inlet Frame and Grate with Curb is commonly specified for:

• Municipal Streets
• Highway Drainage Systems
• Urban Roadways
• Commercial Developments
• Parking Lots
• Industrial Facilities
• Transportation Infrastructure
• Airport Drainage Systems
• Residential Subdivisions
• Stormwater Collection Networks
• Road Reconstruction Projects
• Utility Improvements
• Campus Facilities
• Public Works Installations

Its curb-opening configuration makes it particularly effective where gutter flow must be intercepted before reaching intersections, pedestrian crossings, or low-lying roadway sections.

Technical Specifications

Dimensions are based on Amercast engineering drawings and published product specifications.

Engineering Dimensions

48″ Curb Inlet Assembly

Available Grate Configurations

One of the distinguishing features of this drainage inlet system is the availability of multiple grate patterns, allowing engineers and municipalities to select the configuration best suited for site conditions.

Oval Hole Grate

The Oval Hole configuration provides a large drainage opening while maintaining structural strength for traffic loading applications.

Bicycle Safe Grate

The Bicycle pattern is specifically engineered to reduce the risk of bicycle tire entrapment while maintaining effective stormwater interception.

Streamflow Grate

The Streamflow design promotes efficient water entry while helping optimize hydraulic performance during peak runoff conditions.

Unless otherwise specified, Amercast indicates Bicycle Pattern grates may be supplied as the standard configuration.

EPA 6″ and 8″ Curb Compatibility

The assembly is engineered for installation adjacent to standard EPA-style curb sections.

Benefits include:

• Improved gutter flow interception
• Enhanced stormwater collection
• Reduced roadway ponding
• Increased drainage efficiency
• Compatibility with municipal roadway designs
• Flexible project specification options

The integrated curb throat captures runoff before it bypasses downstream collection points, improving overall drainage system performance. Similar curb inlet systems are widely utilized throughout transportation infrastructure and municipal stormwater networks.

Hydraulic Performance Advantages

Proper stormwater collection is critical to roadway safety and infrastructure protection.

Improved Flow Capture

The elongated curb opening increases the effective interception length compared to smaller inlet structures.

Reduced Surface Ponding

By collecting runoff at curb level, the system helps minimize standing water during storm events.

Infrastructure Protection

Efficient stormwater management reduces erosion, pavement deterioration, and drainage system overload.

Enhanced Public Safety

Removing excess water from travel lanes improves vehicle traction and reduces splash hazards.

Large curb inlet systems are commonly utilized in municipal drainage applications where substantial runoff volumes must be managed efficiently.

Material Performance Characteristics

Gray cast iron continues to be one of the most widely specified materials for storm drainage castings because of its durability and long-term field performance. Heavy-duty drainage castings are commonly produced using ASTM A48 Class 30 or equivalent materials for municipal applications.

Why Choose a Curb Inlet System?

Compared to traditional surface-only catch basin grates, curb inlet structures offer several operational advantages.

For roadways with significant gutter flow, curb inlet systems frequently provide superior hydraulic performance and improved drainage efficiency.

Custom Manufacturing Options

Amercast manufactures stormwater and municipal drainage castings for transportation, utility, and infrastructure projects.

Available options include:

• Bicycle Safe Grates
• Streamflow Grates
• Oval Hole Grates
• Custom Logos
• Municipal Identification
• Agency Markings
• Alternate Frame Heights
• Replacement Grates
• Replacement Frames
• Project-Specific Castings

Custom castings can be manufactured to satisfy agency standards, municipal specifications, and infrastructure project requirements.

Related Products

• Inlet Frames and Grates
• Double Inlet Frame and Grate
• Inlet Frame and Grate with Type N Curb Piece
• Standard Inlet Frame and Grate 5″ High
• Standard Inlet Frame and Grate 4″ High
• Catch Basin Frames & Grates
• Municipal Castings
• Custom Castings

Industry Resource

For guidance regarding stormwater collection systems, roadway drainage design, and hydraulic inlet performance:

Federal Highway Administration (FHWA) – Hydraulic Engineering Circular No. 22 (HEC-22)

https://www.fhwa.dot.gov

HEC-22 is widely recognized throughout the transportation industry as a leading reference for the design and evaluation of urban storm drainage systems and roadway inlets.

Why Choose Amercast?

Amercast manufactures cast iron drainage products serving municipalities, engineers, contractors, utility authorities, transportation agencies, and infrastructure owners throughout North America. Our inlet frames, curb inlets, catch basin castings, grates, and drainage components are engineered for reliability, performance, and long-term durability in demanding stormwater applications. Amercast offers one of the industry’s broadest selections of cast iron infrastructure products for roadway, utility, wastewater, and drainage systems. (American Cast Iron Products, Inc.)

Request a Quote

Need pricing, CAD drawings, hydraulic submittals, replacement grates, municipal specifications, or custom drainage castings?

Contact Amercast today to request a quote for the 48″ Inlet Frame and Grate with Curb. Our team can assist with roadway drainage systems, stormwater infrastructure, municipal castings, transportation projects, and custom-engineered drainage solutions throughout North America.