Federal Highway Administration

HEC-21 Design of Bridge Deck Drainage

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Compare each cited field to the official PDF before relying on it. What this means

Title/edition from FHWA Highway Drainage publications list (HEC-21, May 1993). Corpus focuses on bridge deck drainage, not site-scale stormwater BMP design. water_quality_volume_method not addressed in provided text.

Fields not found in document: document_metadata.adoption_or_effective_date, document_metadata.last_revised_date, design_criteria.water_quality_volume_method

Other federal manuals: HDS-4 Introduction to Highway Hydraulics, HEC-14 Hydraulic Design of Energy Dissipators for Culverts and Channels, HEC-15 Design of Roadside Channels with Flexible Linings, HEC-22 Urban Drainage Design Manual, HEC-24 Highway Stormwater Pump Station Design

Document Metadata

Jurisdiction level

Federal

“software package supported by the Federal Highway Administration (FHWA).”
107

State

Not found in document

No evidence cited

Version / edition

May 1993

“Chapter 9 : HEC 21 Bridge Deck Drainage Method”
49

Adoption / effective date

Not found in document

No evidence cited

Last revised date

Not found in document

No evidence cited

Relationship to state manual

independent

“This manual takes the viewpoint that inlets are designed not to clog.”
106

Design Criteria

Design storm return periods (years)

2-year, 5-year, 10-year, 50-year

“Functional Class of Roadway ... Frequency (Return Period--years) Interstate ... 10 ... Major Collectors and Arterials ... 10 ... Minor Collectors and Arterials ... 5 ... Local Streets ... 2 ... Depressed Interstate Drained by Pumping Stations ... 50”
105-106

Water quality volume method

Not found in document

No evidence cited

Peak flow calculation method(s)

Rational Method

“The Rational Method is presented as the conventional method for determining peak runoff rate for bridge decks.”
105

Hydrologic/hydraulic software

HYDRAIN, HYDRO

“The IDF curve can be obtained from HYDRO in the HYDRAIN software using the latitude and longitude coordinates of the site.”
92

Approved BMP categories

retention ponds, detention ponds

“Retention and detention ponds, with or without permanent pools, can be provided to attenuate peak flows or provide quiescent conditions to settle out particulates.”
104