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Dave Hensberry, EITAssistant Hydraulics EngineerNYSDOT – Region 9 Binghamton

An Introduction to HY-8 Culvert Hydraulic Analysis Program

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Overview• What is HY-8• Where can you get it• Uses• Advantages/Limitations• Design Requirements• Example project (s)

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What is HY - 8• Hydraulic computation model for roadway

stream crossings (culverts)

• Created & Provided Online by FHWA: • FREE Software• Download @

https://www.fhwa.dot.gov/engineering/hydraulics/software/hy8/

• Current Version is HY-8 7.50 • Build Date July 28, 2016

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• Analyze the performance of culverts

• Velocities• Water Depths• Flow Profiles

• Analyze multi-barrel structures

• Analyze multiple crossings in one

project

• Analyze roadway overtopping

• Develop report tables and graphs

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• Modify cross section designs• Circular• Box• Ellipse• Arch

• Modify elevations

• Modify lengths

• Modify inlet/outlet conditions

• Modify materials

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Advantages

Simple to Use Free Software No Hydraulic Cross-

Sections required (Survey)

Can quickly change design and analyze

Limitations Only single stream

crossings Not appropriate for

bridges with piers Does NOT replace

HEC-RAS Analysis

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Culvert #1Culvert #2

Will NOT analyze culverts “In-Line”

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Analyze Multiple culverts in one project file

Culvert #1

Culvert #4

Culvert #3

Culvert #2

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1. The values in this table are typical. The selected valuefor a project should be based upon an assessment ofthe likely damage to the highway and adjacentlandowners from a given flow and the costs of thedrainage facility. Note: 100-year requirements must bechecked if the proposed highway is in an establishedregulatory floodway or floodplain.

6. A design flood frequency of 10 or 25 years is acceptable if documented in the Design Approval Document, and when identified after design approval, in the drainage report. A design flood frequency of 10 or 25 years should be used in the design of driveway culverts and similar structures.

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FEMA National Flood Hazard Layer

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NYS Route 17 over Dry Brook (Tioga County)

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What you need:

• HY-8 Software• Discharge Data (Stream

flow)• Tail-water Data• Roadway Data• Culvert Data• Site Data

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Creating a New Project in HY-8

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Discharge Data“Stream Stats”

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Top View

Dry Run Brook

Slope (So) = 0.11324 ft.

Roadway Station 1 +00

320 ft

Crest length

Top Width

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Cross Section View

Inlet Elevation = 820 ft. Outlet Elevation = 819 ft.

Slope (So) = 0.0031Dry Run Brook

847 ft.

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Cross Section View

Inlet Elevation = 820 ft. Outlet Elevation = 819 ft.

Slope (So) = 0.0031Dry Run Brook

847 ft.

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Cross Section View

Inlet Elevation = 820 ft. Outlet Elevation = 819 ft.

Slope (So) = 0.0031Dry Run Brook

847 ft.

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Cross Section View

Inlet Elevation = 820 ft. Outlet Elevation = 819 ft.

Slope (So) = 0.0031Dry Run Brook

847 ft.

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Cross Section View

Inlet Elevation = 820 ft. Outlet Elevation = 819 ft.

Slope (So) = 0.0031Dry Run Brook

847 ft.

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Analyze your Crossing

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View Results (Design Flow Q50) - Existing

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With 8” Paved invert

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View Results (Design Flow Q50) - Proposed

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Existing Vs. Proposed

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Design Details for Structural Invert Paving of Culverts

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Design Details for Structural Invert Paving of Culverts

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NYSDOT Standards

NYSDOT Bridge ManualBridge Detail (BD) Sheets – EE5ER2

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Slip Lining ExampleCurrent pipe is a 3’ circular CMP drainage pipe. Question - Can I slip line with 2’ concrete pipe?

Design Flow = 50 cfsMax Flow = 100 cfs

Channel width = 10 ftSlope = 0.0025 ft/ftManning’s n = 0.050Crest Elevation = 307 ft(top of road)

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Cross Section View

307 m

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Slip Lining Results

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• Analyze the performance of culverts:• Velocities• Water Depths• Flow Profiles• Multi-barrel structures• Multiple crossings in one project• Roadway overtopping i.e. Weir flow

• Develop report tables and graphs

BTW this would be considered a bridge!

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Assessment of Learning1. According to the NYSDOT Bridge Design Manual, Extra

Heavy Stone Protection must be used for velocities (V) greater than 10 fps?

a) Trueb) False

Extra Heavy Stone for V > 12 fps

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Assessment of Learning2. When designing a culvert replacement or repair, when is it required to analyze the 100-year (Q100) flood?

a) Any new replacementb) Only when using Class J concretec) Whenever the culvert is within the regulatory Floodway or

Floodplaind) None of the Above

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Assessment of Learning3. HY-8 Software has the ability to analyze all of the following except?

a) Multi Barrel Structuresb) Velocitiesc) Roadway Overtoppingd) In-Line Culverts