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Hydraulics

INDOT Hydraulic Engineering designs or reviews all waterway projects including, but not limited to, bridges, culverts, storm sewers, and detention ponds along state roads, U.S. routes or interstates or local projects built with state or federal funds.  

Index

Developing Design Guidance

  • Bridge
    • For a scour analysis and if a bridge is on piles, the traditional "10 foot rule from the bottom of the piles" is no longer used.  If a the piles are in anyway exposed during a scour event, the scour determination is sent to part B of the scour memo and the bridge structure engineer at INDOT will determine the scour criticalness.  If the piles are undermined, then the bridge may be determined scour critical from the hydraulic engineer.
    • When conducting scour design, the IDM states to use the channel only, however due to the fluctuation of channel embankments, it may not be the highest value of the calculations. Therefore the greatest contraction scour depth between the left, right or center values found in Hec-RAS should be used when reporting the scour depth.
    • Existing single span structures greater than or equal to 20 ft and up to 30 ft in perpendicular span to the conveyed channel may have proposed structures sized in HY-8 version 7.2. This only applies to proposed structures that can be modeled in HY-8 using a pre-defined HY-8 shape in the culvert data section of the crossing data input, and have a perpendicular span to the conveyed channel within the aforementioned span range.  The Office of Hydraulics must be consulted before modeling slab-top structures within the aforementioned span range
      • Note: Three-sided and four-sided concrete structures that are less than 18 ft in perpendicular span to the conveyed channel will still need to be modeled with HY-8 incorporating haunches using the user defined shape options.
    • The scour protection for vertical abutment bridges in Figure 203-3B is no longer in effect to where the riprap should have a lay width twice the water depth or a minimum of 10 ft. Please follow Standard Drawing E723-CCSP-04 of using a minimum width of 6 ft from the edge of the footer.
  • Small Structure
    • CLARIFICATION OF IDM 203-2.02(02) 2.a.1.: The replacement structure does not have to have the same span as the existing structure when the existing structure is going from pipe to a proposed box type structure.  However, the cross-sectional structure area cannot be reduced.
      • Example:  An existing twin 8 foot diameter pipes may be replaced with a proposed 15x7 box structure, even though the twin pipes have a total span of 16 feet while the box has 15 feet, as long as the proposed total area is equal to or greater than the existing.  In this case, the existing area is about 101 square feet, while the proposed box (with haunches) has an area of 103 square feet.
      • Example 2:  An existing 6 foot diameter pipe cannot be replaced with a 5x5 box because the existing pipe has an area of 28 square feet, while the proposed box (with haunches) has an area of 23 square feet.
    • The invert of a jack and bored pipes will be set to a minimum of 1 ft above the invert of the existing pipe to be lined.  If this is not feasible due to site constraints, please coordinate with the INDOT Hydraulic Engineering.
    • All liner options should have the inverts of the pipes raised by the liner thickness.  Backwater should then be calculated by taking the existing culvert's backwater and subtract the difference of the headwaters.
    • HY-8 v.7.2 is currently the only version permitted for use by the INDOT Hydraulic Engineering.  Please click the following link to download the software. (Active Design Memoranda16-34).
      • Due to Window's updates, HY-8 v.7.2 will not install without first installing the  application that can be downloaded by clicking here. After this application is installed, HY-8 v.7.2 may be installed.
    • Jack and bore pipes as part of a culvert liner project under the interstate are required to have a minimum inner diameter of 18 inches.
    • For consistency of sump requirements and without more detailed information, if the soil map unit description contains the word sand, the required sump from IDM Fig 203-2E should be based off of the "Sump Required for Stream Bed of Sand" column.
    • Reinforced concrete boxes and 3 sided structures under 18 foot span should incorporate corner haunches as produced by the manufacturer.  The spreadsheet provided below, named Specialty Structure Coordinate Generator under Other Links and Forms, includes the haunch data from the manufacturers.
    • A flow chart has been developed to help designers select which structure and liner options should be analyzed.  Modeling guidance has also been included.  This chart can also be found as Proposed Structures Flow Chart under Other Links and Forms below.
      • Semi-smooth options will no longer be required to be given as replacement options for small structures.
    • All three-sided structures are no longer required to be sumped unless requested by the county surveyor for legal drains.
    • When analyzing an existing structure that is showing overtopping, the designer should NOT artificially raise the road to analyze headwater elevation as it may exaggerate the backwater total, but rather make certain that the discharge through the liner/new pipe at overtopping is greater than the existing.
    • For a culvert rehabilitation project, a pipe liner should not be used if it has a inner diameter less than the minimal allowable for the particular roadway facility.  See IDM Figure 203-2B.  If the host pipe is a median drain or storm sewer, the pipe liner should not have an inside diameter less than 12".
  • Hydrology
    • If a dual hydrologic soil group is within a watershed, then the soil should be considered undrained (D-soil) unless it can be shown that the water table is more than 24 inches below the ground surface. If desired, the groundwater depth can be found using the USDA Websoil survey.
  • Steel Liners

    When considering a smooth steel liner, the following guidelines should be followed:

    1. Consider a steel liner when a CIPP is over 6 ft in span or if the district has specifically requested the option.
    2. When modeling, the minimum gap between the inside of the liner and inside of the host pipe is 5 inches on top and 4 inches along each side. This is to account for the grout and wall thickness of the liner.
      • For circular steel liners, the inside diameter of the existing structure can be reduced by 8 inches to calculate the proposed inside diameter.
      • For corrugated metal pipe arches (CMPA), the Coordinate Generator for CMPA Liners is recommended to be used to obtain modeling coordinates of the proposed liner.
    3. The liner is expected to lay directly on the host pipe resulting in an invert rise of 1 inch for modeling purposes. The actual thickness may vary per manufactures recommendations.
    4. A Manning’s n value of 0.012 should be used for analysis and design of the proposed steel liner.
    5. The inlet condition should match the existing structure unless an improved inlet is being recommended.
    6. For the Hydraulics Memo, please describe the assumed thickness of the liner and the minimum internal dimensions (I.D.)
      • Example: 1-inch thick Smooth Steel Liner, 143” (I.D.) Span x 94” (I.D.) Rise
  • Median Drains

    All median drainage should be submitted to INDOT Hydraulics for review. The IDM is limited in guidance for median drainage design and submittals. The following should be used in conjunction with the IDM to produce an optimal median drainage design for INDOT purposes.

    1. The minimum size is a 12 inch inner diameter.
    2. Medians for added travel lanes should be designed so that no spread enters the edge of travel lane for a 100-year storm event.
    3. Minimal Rational C value used for pavement shall be 0.90.
    4. For unpaved medians, Type N inlets shall be used in the median unless they physically cannot geometrically fit for non-paved medians. In that case a Type P inlet will be allowed.
    5. For paved medians, inlet spread calculations shall include 50% clogging factor for all inlets on grade. The clogging factor shall not be required for sag inlets with flanking inlets, for P-12 or N-12 inlets and for inlets with curb openings.
    6. Flanking inlets are required at each sag inlet location. The flanking inlets are required on both sides of the sag inlet if flow is from both directions. If the flow is from one direction only, then one flanking inlet is required. If the required distance from the sag inlet to the flanking inlet is greater than the distance to the next adjacent upstream inlet, then dual inlets may be provided as an exception. The dual inlets should be connected by a 6’ section of pipe. The flanking inlets are not to be used in the spread calculations.
    7. No detention is allowed within the median or under the roadway pavement.
    8. No drainage from the outside ditch shall be brought into the median drainage system. Where drainage from the outside ditch or flow from outside of the right-of-way is to be conveyed to the opposite side of the road with a separate culvert that is not connected to the median drains.
    9. Each median drain shall have a separate pipe draining to the outside. Flanking inlets will be permitted to be connected to the sag inlet. The inlet on the opposite side of the barrier wall at the same station will be allowed to be connected. Median drainage structures shall drain directly to outside ditches as soon as practical.
    10. New median or storm sewer drain outlets shall be 12” above the ditch flowline elevation. A minimum of 6” may be allowed, but a hydraulic grade line (HGL) check shall be required with the appropriate side ditch water elevation and submitted to INDOT Hydraulics for review and approval. If these requirements cannot be met, coordinate with INDOT Hydraulics to obtain a design exception.
    11. Median outlets shall be above the Q100 elevation of detention facilities and receiving waters. If this cannot be achieved, an HGL analysis of the median drain with the high tailwater at Q100 elevation shall be required and submitted to INDOT for review and approval.
    12. Slotted drains may not be used in the drainage calculations. Trench drains may be used in the drainage calculations for spread, if the minimal grate width is 12”.
    13. Proposed drainage area maps shall be provided. The proposed drainage area maps shall include proposed grading at 1 ft contour intervals, proposed median inlet structures and piping and flow direction arrows.
    14. Existing drainage area maps shall be provided. The existing drainage area maps shall include existing grading at 1 ft contour intervals, existing median inlet structures and piping and flow direction arrows.
    15. Spreadsheet submittals for median drains should include the following beyond the typical HGL calculations required for storm sewers in the IDM, this includes, hydraulic grade line, edge of travel lane elevation, structure rim elevation, structure invert elevation, tailwater elevation (define if different than pipe outlet depth), receiving ditch flowline elevation, etc.
  • Infiltration Ponds

Prequalification and Training Courses

INDOT Hydraulics has launched a Driveway Permit Training Course.  It is a course that we have developed for consultants that are submitting driveway permits that include drainage design that drains to the INDOT right-of-way.  We will be requiring that the course be completed for a consultant to become prequalified for this type of work.  In August of 2018, we will no longer review drainage design submittals for driveway permits from consultants that are not prequalified. Please note this training course will take about 1 hour to complete. It is taken online at your own convenience.

If you would like to be signed up for the course, please follow the detailed instructions on how to register for the course in the link below. If you run into any issues regarding registration for this course, please email Hydraulics@indot.IN.gov.

Instructions to Access INDOT Hydraulics Training Courses

INDOT Hydraulics has launched a Small Structure and Pipe Hydraulics Training Course.  It is a course that we have developed for consultants that are submitting small structure and culvert designs. Please note this training course will take about 1 hour to complete. It is taken online at your own convenience.

If you would like to be signed up for the course, please follow the detailed instructions on how to register for the course in the link below. If you run into any issues regarding registration for this course, please email Hydraulics@indot.IN.gov.

Instructions to Access INDOT Hydraulics Training Courses

INDOT Hydraulics has launched a Bridge Hydraulics Training Course.  It is a course that we have developed for consultants that are submitting Bridge and Scour designs. Please note this training course will take about 1.5 to 2 hours to complete. It is taken online at your own convenience.

If you would like to be signed up for the course, please follow the detailed instructions on how to register for the course in the link below. If you run into any issues regarding registration for this course, please email Hydraulics@indot.IN.gov.

Instructions to Access INDOT Hydraulics Training Courses

INDOT Hydraulics has launched a Storm Sewer and Detention Design Training Course.  It is a course that we have developed for consultants that are submitting storm sewer and detention designs. Please note this training course will take about 1 hour to complete. It is taken online at your own convenience.

If you would like to be signed up for the course, please follow the detailed instructions on how to register for the course in the link below. If you run into any issues regarding registration for this course, please email Hydraulics@indot.IN.gov.

Instructions to Access INDOT Hydraulics Training Courses

Upcoming  Training

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Frequently Asked Questions

Contact Information

Mark Bailey
Director of Hydraulics
Indiana Department of Transportation
100 N. Senate Ave., N758 - Hydraulics
Indianapolis, IN 46204
317-233-2096
MBailey1@indot.in.gov

Hydraulics@indot.IN.gov

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