Darrin Miller PE Hydraulic Engineer Section Manager (North)

Non-modeling Worksheets: Bridge Replacement in Kind

April 12, 2016

Overview

• Intent - When to use the Worksheet • Theory behind the Worksheet • Bridges and Culverts • Examples

Non-Modeling Worksheet

When to Use the Worksheet • Bridge to Bridge replacement • Culvert to Bridge replacement • Culvert to Culvert replacement

– If the length of the culvert is essentially the same – And if the proposed culvert is of essentially the same

material (roughness coefficient) – http://www.hec.usace.army.mil/software/hec-ras/documents/HEC-

RAS_4.0_Reference_Manual.pdf (page 6-24) – Concrete is typically smoother than corrugated metal, smaller “n”,

less loss, lower surcharge

• Note: If multiple designs, the applicant should only submit the one with the smallest waterway opening for use in the worksheets

April 12, 2016

Non-Modeling Worksheet

When to Not Use the Worksheet • The waterway opening decreases • The existing structure remains in place • Bridge to Culvert replacement • If the New bridge is more than 500 ft from the

existing bridge

Non-Modeling Worksheet

How to Use the Worksheet • The worksheet was intended to streamline the

majority of replacement in kind projects • BUT, it does not capture every possibility

• Single page • Excel with “if then” statements

Non-Modeling Worksheet

How to Use the Worksheet • The worksheet was intended to streamline the

majority of replacement in kind projects • BUT, it does not capture every possibility • 1) It works for my bridge: submit worksheet • 2) It does not work for my bridge: modeling • 3) It does not work for my bridge, BUT it should

– include documentation for DNR review to fill in the

missing info not captured by the Excel worksheet

Non-Modeling Worksheet • Directions for use • Minimum

Requirements • Check Sheets • Plan Details

Companion Worksheet B

• Excel Spreadsheet with embedded logic to evaluate entries

• Yes/No questions with dropdown choices

• Tables for recording relevant data

Two Part Application

Minimum Requirements

• Plan view of construction components • Aerial of disturbed area • Delineated Floodway through the project • Plan views with calculations of waterway

opening, top of road profile, and low structure • Cross section location map • Project location map • Site photos

Companion Worksheet B

• Questions are asked in an order so that the applicant will move through the worksheet as quickly as possible while providing as little information as is needed to determine the ability to issue a permit for the project

• Logic is coded into the spreadsheet so the applicant is only asked for applicable data

Presenter

Presentation Notes

We have taken the original Companion worksheet B and embedded the logic of the worksheet into an excel workbook. This means that the excel will now evaluate the information that is input into the tables and determine if the project is eligible to be evaluated through the Bridge Replacement in Kind process. We will now step through the process of filling out the worksheet and how the spreadsheet works.

Presenter

Presentation Notes

As long as the proposed waterway opening is larger or equal to the existing waterway opening you will be prompted to answer the next three questions

Culverts & Bridges

Why is it important to consider if it’s a bridge or culvert?

• When modeling in HEC-RAS, bridges and culverts are modeled differently which can give drastically different results

• Bridges are modeled using the methods

selected in the bridge modeling approach editor (Energy, Momentum, Pressure and/or Weir, …)

Culverts & Bridges

Why is it important to consider if it’s a bridge or culvert?

• Culverts also come in many different shapes (box, arch, circular, ellipse, …)

• Culverts can be made of different materials

which have different roughness coefficient

• Culverts are modeled using inlet or outlet control culvert equations and when applicable weir equations

Culverts & Bridges

When is it a bridge and not a culvert?

• Consider bridge methods when the structure has a very large opening relative to the deck thickness

• Consider culvert methods when the structure

has a very deep deck and small relative opening

• FHWA defines a culvert as a structure with a total span of 20 ft or less (measured along centerline of roadway)

Culverts & Bridges FHWA defines a culvert as a structure with a span of 20 ft or less (measured along centerline)

Non-Modeling Worksheet

So when can I use the worksheet?

• Theory behind logic is to approve in-kind

• Would the same equations be used to model

both structures?

Presenter

Presentation Notes

From step 2 on the excel sheet can take two different paths based on the aspects of the bridge replacement. We will now look at a specific example of the spreadsheet in use.

Presenter

Presentation Notes

This example is a replacement of a bridge where the waterway opening is not changing and the bridge replacement meets all the criteria in step 2B. Also the profile is changing.

Presenter

Presentation Notes

Because guardrails are being added. So now the sheet needs a BFE.

Presenter

Presentation Notes

And a source.

Companion Worksheet B

• Regulatory Flood Elevation (RFE) is needed to evaluate the area available below the RFE

• At toe of road fill

• Acceptable sources: – a published Flood Study – a Letter of Map Revision (LOMR) – an approved model(s) from a DNR permit – a DNR Floodplain Analysis and Regulatory

Assessment (FARA) – a new model submitted with the permit

application for DNR review

Presenter

Presentation Notes

Now after all the information has been entered we see the result that this bridge is eligible to be reviewed as a Replacement in Kind.

Supporting Documents

• Minimum submittal requirements listed on the evaluation worksheet

• Submit all that is needed to support the calculations and values in the RIK assessment worksheet.

• If your project is unique, submit the non-modeling assessment with the supporting documentation and DNR can review.

Examples

• Bridge deck improvements result in thicker deck. The low chord of the proposed bridge (red line) has a lower elevation than existing. Does it qualify?

Proposed

Existing

1% BFE

Examples

• Yes. The area of the waterway opening beneath the structure is decreasing. But since the BFE is known, it can be shown that the area below the BFE is NOT changed.

Proposed

Existing

1% BFE

Examples

• The proposed road profile is raised and minimum top of road remains unchanged.

• Does it qualify? Proposed road profile

Minimum top of road

1% BFE

Examples

• No, the worksheet captures the high structure elevation, and the minimum top of road.

• But additional road fill may block road overflow. Proposed road profile

Minimum top of road

1% BFE

Examples

• The proposed road profile will be raised above the existing minimum top of road.

• Does it qualify?

Proposed road profile

Minimum top of road

1% BFE

Examples

• Yes, the worksheet captures the high structure elevation, and the minimum top of road.

• Both are above the BFE.

Proposed road profile

Minimum top of road

1% BFE