Introduction to Bridge Design and

Construction 1

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Introduction to Replacement Bridge Planning and Design

Questa Engineering Corporation

Sydney Temple, P.E.

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Introduction

Today’s Talk:

Basic site analysis and investigation Geotech, Hydrology, Roadway, etc.

Bridge designs types Abutment/Foundation types

Bridge Deck types

Design exercise

Permits and review processes

Construction issues

Retrofits

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Why Bridges?

Bridges have better Flood Control performance

Less back water, better conveyance, safer

Geomorphic flexibility Maintains sediment transport, vertical

movement

Fisheries benefits Removes migration barriers, facilitates

movement, provides habitat

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Introduction to Bridge Design and

Construction 2

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Multi-Discipline Approach

Structural Engineering

Geotechnical Engineering

Civil Engineering

Planning and Permitting

Hydrology Science

Hydraulic Engineering

Biologic Evaluations

Geologic Evaluations

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Basic Design Approach

Investigate the site

Survey and geotech

Layout bridge location

Bridge Deck and foundation design

Hydraulic Design

Approach design

Permitting

Construction

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Site Survey Data

A GOOD SURVEY IS NEVER A WASTE OF MONEY!!

Survey site General topographic for 100 feet upstream downstream min.

Channel slopes Long profile at 350 feet upstream and downstream

Make sure controlling tailwater zones are surveyed

Existing structure data Slope, shape, dimensions, top of roadway, top of culvert, apron

slopes and wing wall geometries

Make sure bridge approach roads are surveyed including edge of pavement, roadway crowns, super elevations

Map utilities and nearby structures

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Site Analysis

Site analysis:

Layout

Geotechnical Considerations

Hydrologic/Hydraulic Studies

Geomorphic Considerations

Biologic issues

Introduction to Bridge Design and

Construction 3

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Bridge Layout – Structure Positioning

Right of Way

Jurisdictional determination

Alternative alignments

Approaches

Vehicular

ADA Requirements

Traffic/Roadway design

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Roadway Design Issues

Alignments

Approach elevations

Vertical Curves

Will you need embankments or other retaining structures

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Geotechnical Studies

Investigative procedures

Drilling rigs and types

Constraints

Report preparation

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Types of Geologic Investigations

Regional gelogic and seismic conditions

Soil conditions

Geologic hazards

Subsurface exploration

Analysis

Design recommendations

Introduction to Bridge Design and

Construction 4

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Local Geologic Map Detail of Cambria Area

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Soils Map

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Regional Seismicity and Geology Review

Alquist-Priolo Earthquake Fault Zone Maps

Seismic Hazard Zone Maps

Liquefaction

Seismic Induced Slope Instability

Seismic Shaking Hazard Maps

Regional Geologic Mapping

Regional Slope Stability Mapping

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Drilling, Logging and Sampling of Boreholes

Exploratory holes 10 feet into bedrock or required depth in soils

Soil sampling at depth intervals to collect samples for analytical testing

Perform Standard Penetration Test (SPT) sampling for strength characteristics (I.e. Blow Counts/ft)

Determine groundwater levels

Introduction to Bridge Design and

Construction 5

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Drill Rigs

Type of rig depends upon many factors;

Depth of hole,

required rock penetration,

potential for hole collapse,

sampling requirements, and

access restrictions

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Drill Rigs

Portable Augur Drill Rig

Truck/track mounted Augur Drill Rig

Mud or Air Rotary Drilling

Cone Penetration Testing

Re: Specialized drilling services may take time to schedule

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Types of Drilling

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Reviewing Boring Logs

Logs of test borings show summaries of data

Soil density

Soil material

Blow counts

Fewer blow counts - looser less dense material

High blow counts - solid denser soil conditions

Groundwater levels

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Introduction to Bridge Design and

Construction 6

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Foundation Type Feasibility Review and Laboratory Testing Request

Review Logs of Boreholes and Determine Feasible Foundations based on subsurface conditions

Determine Samples and Testing Protocol for Soils Laboratory

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Geotechnical Engineering Analysis

Foundation bearing capacity

Site seismic design criteria

Pier Friction Capacity

Liquefaction Analysis

Site Geology and Soil Conditions

Geologic Hazards

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Session Break

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H & H Investigations

Hydrology data

Hydraulics analysis

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Hydrologic Analysis

Hydrology Information

Gage data

Hydrologic models

Comparable basin analysis

Governmental sources; Caltrans, FEMA, and County Flood Control Agencies

Introduction to Bridge Design and

Construction 7

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Hydraulic Analysis

Hydraulic analysis

FishXing

HEC-RAS

Alternative Hydraulic models

Must have the ability calculate back water impacts

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Project Site

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Hydraulic Modeling

HEC-RAS

Good design tool accepted by most if not all agencies for analysis

Requirements:

Accurate topographical survey

Surveyed benchmarks

Hydraulic structures

Bridge soffit/roadway measurements

Slope

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Design Water Surface elevations

Hydraulic Design Criteria and Freeboard

Vary by Jurisdiction

50-year with 2 ft of freeboard

100-year with at least 1 ft freeboard

Levees – three of freeboard

Introduction to Bridge Design and

Construction 8

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Bridge Design and Impacts

Goal: shortest bridge with the least amount of impact

Design Criteria

Passes design flows with freeborad

50-year with 2 ft of freeboard

100-year with at least 1 ft freeboard

No increase in flood threat

Minimizes scour and deposition

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Bridge Scour Analysis

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Bridge Scour

Event Based scour vs. Long-term scour

Hydraulic Engineering Circular (HEC) 18,

"Evaluating Scour at Bridges," FHWA-IP-

90-017

Geomorphic evaluations

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Geomorphic Analysis

Vertical & Lateral Creek Movement

Sediment Transport

Bankfull channel

Low-Flow (scour line) Channel

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Introduction to Bridge Design and

Construction 9

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Determining Vertical and Lateral Creek Movement

Historic profile analysis

Existing condition long profile analysis

Historic air photo examination

Historic topographic map analysis

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Lateral movement

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Longitudinal Profile Analysis

70

80

90

100

110

120

130

140

150

-1+50 3+50 8+50 13+50 18+50 23+50 28+50 33+50

River Station (ft)

Flo

w L

ine

Ele

va

tio

n (

ft)

Reach 3Reach 2Reach 1

Mitigated Knickpoint (armored)

Un-mitigated Knickpoint

Dri

sco

ll R

oad

Pal

m A

ven

ue

SF Aqueduct,

concrete

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Longitudinal Profile Analysis

Determines average slope through the site

Assesses offsite bed slope issues

Places project site in context with upstream downstream areas

May indicate bed aggradation

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Fall 2003 March 2005

Introduction to Bridge Design and

Construction 10

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Design Breakdown

Foundation design

Bridge deck design

Channel Design

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Bridge Foundation Considerations

Required Load Capacity and Anticipated Uses

Site Conditions & Geotechnical Investigations

Foundation Types Spread Footings

Driven Piles

Drilled Cast-In-Place Piers

Economic Analysis Capacity and Service Life versus Cost

Typical Construction Costs

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Required Load Capacity and Anticipated Uses

Public Trails -

Pedestrian/Bicycle/Equestrian/Disabled Users

Light-Duty – Typically Residential

Automobiles/Light Trucks

Highway Traffic – Heavy Trucks HS20-25 loads

(AASHTO Load Standards)

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AASHTO & Caltrans

American Association of State Highway and Transportation Officials

National Association which establishes and promotes highway construction and safety standards.

California Department of Transportation

Manages State Highway System

Issues permits for encroachment into state owned highways and properties

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Typical Light-Duty Bridge Crossing Profile

80

0+00 0+40 0+80 1+20 1+60 2+00 2+40 2+80

94.4

94.3

94.1

93.5

93.1

90.7

89.7

86.0

82.9

81.2

83.9

86.5

92.5

96.0

97.0

98.0

98.8

99.7

100

.2

100

.2

100

.2

100

.2

100

.2

99.2

98.2

97.2

90

100

94.4

95.3

96.2

97.1

96.8

96.7

2+91

80

90

100

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Introduction to Bridge Design and

Construction 11

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Foundation Types - Spread Footings

Relatively shallow reinforced concrete mats to distribute bridge loads over wide area of supporting soils.

Advantages

Typically least expensive option

Minimal equipment mobilization requirements

Disadvantages

– Not suitable over soft or liquefiable soils

– Minimal resistance to undermining or slope instability

– Moderate to heavy site disruptions

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Typical Spread Footing Bridge Foundation

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Foundation Types - Driven Piles

Tubular and Sheet Steel, Reinforced Concrete or Composite Piles driven into soils using a dropped weight or piston hammer, applied typically in marine settings.

Advantages Minimal site disruption

Provides support over soft or variable subgrade conditions

Applied in areas prone to flooding or with very soft soils

Disadvantages Requires mobilization of large equipment and materials

Requires minimum embedment depth into soil

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Reinforced Concrete Piles Being Installed in a Marine Environment

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Foundation Types - Drilled Cast-In-Place Piers

Drilled holes filled with cast-in-place reinforced concrete piers.

Advantages Typically provides greatest resistance to vertical and lateral

loads

Provides excellent resistance to scour

Used in steep and/or unstable slope areas

Disadvantages Typically highest cost

Difficult to apply in areas of shallow ground water or loose soils

Moderate site disruptions

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Drilled Pier Foundation Design for Timber Framed Bridge

#4 BAR

#4 BARS

FOR STEM WALL

1'

3'-4"

14'-8"

#4 HOOPS @12" O.C.

4 #5

3" COVER3' COVER

58" X 12" ANCHOR

BOLT @ 48" O.C.

12"

#4 HOOPS @12" O.C.

4 #5

9 #5

7 #4

8"

12"

1'

5'-8"

10'-0"

12"

8"

3" COVER

3" COVER

2'-4"

7 #4

12"

12"

12"

12"

14'-8"

3'-8"

10'-0"

#5 #4

C'

B

3" COVER3" COVER

#4 HOOPS @12" O.C.

4 #5

#4 HOOPS @12" O.C.

4 #5

3' MIN.

12"

12"

7 #4

B

PLANSECTION B-B'

SECTION C-C'

SECTION A-A'

C

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Construction 12

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Photo of Drilled Cast-In-Place Pier Installation

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Economic Analysis

Capacity and Service Life versus Cost

Typical Cost for Light-Duty Bridges $1,000/ft for pre-fabricated steel bridges

w/ wood decking

$2,000/ft installed including design and foundations

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Concrete Box Girder

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Introduction to Bridge Design and

Construction 13

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Bridge Widths

12 foot width lanes plus 2 feet of railing/curb

Single lane = 18 feet, 14 feet between railings/curbs

Two Lane = 28 feet, 24 feet between railings/curbs

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Planning Level Bridge Costs

Pedestrian Bridge construction costs in northern California $125-$140 per square feet (sf) for cast in place concrete, $115-$150 per sf for prefabricated bridges. $1,500 per lineal foot

Traffic Rated Bridges Two Lane light to medium traffic

$350-500 sf

Major arterial structures $600-$750 sf

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Picture of ferrasci improvements

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Introduction to Bridge Design and

Construction 14

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Project Concept

CEQA

Certification

Flood Control

Public Safety

Permits

Environmental

Permits

Implementation

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Permits and Approvals

Documents needed for permitting

Permitting procedures

Design Review

Construction implementation

Construction management and inspection

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Project Permit Documents

Site Map Water of the USCOE Jurisdictional Area Project Description Detailed Alternatives examined/project justification 30% design drawings

Project Analysis Technical analysis or separate back up design

memorandum (H&H, Geotech, etc.)

Biologic Reconnaissance

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Project Description

Project Justification Site plan

Project channel bed profiles

Project cross section views

Habitat enhancement features

Limits of work

Area of impact

USCOE, riparian area, vegetated area

Determination of cut and fill quantities

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Environmental Permits

U.S. Army Corps of Engineers 404 Permit

Endangered Species Act Consultation

California Department of Fish & Game Streambed Alteration Agreement

Regional Water Quality Control Board

Water Quality Certification & General Stormwater Construction Permit

Coastal Development Permit

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USCOE Permits

Reviews application and notifies National Marine Fisheries Service (NMFS) and/or US Fish and Wildlife Service (USFWS)

May ask for formal or informal consultation

May require preparation of a Biologic Opinion (BO) and/authorization for take

NMFS will review Fish passage analysis

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Construction 15

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Streambed Alteration Agreements

CDFG engineering staff will review project fish passage analysis

Must have CEQA completed to issue

Includes impacts to riparian areas

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Biological Reconnaissance

Special-Status Species

Existing Habitat ID and Mapping

Proposed Habitat Mitigation

OHWM/Wetland Delineation

CNDDB Search

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Coastal Development Permit

Usually processed through the County

May require architectural review

May require separate monitoring protocols

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Public Safety Permits

County/ City Building Permits

Structural & Roadway Design Review

Caltrans

Encroachment permits

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Construction 16

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Caltrans Encroachment Permit

Primarily concerned with impacts to their facilities and safety

Reviews design storm hydrology and hydraulics

Erosion and bank stabilization in and around their facilities

Maintenance responsibility

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County/City Review

Reviews detail plans and calculations

Roadway design

Structural design

Geotechnical design

Flood control

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CEQA Review

Categorical Exemption

Initial Study Preparation

Mitigated Negative Declaration

EIR/EIS

Lead Agency

City or County

CDFG for some grant funded projects

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Permit Timeline

6 month is likely minimum

1 year is not out of the question

NMFS and USFWS have 135 days

CDFG - 30 days

Coastal Development Permit

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Construction Factors

Site and Channel Access

Work Conditions

Restricted Seasons

Mobilization and Staging Areas

Materials Storage Areas

Dewatering

Limits of Work

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Construction 17

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Construction Issues Access & Staging

How are you going to get to the site?

Dewatering issues

Do access roads need to built?

How will machinery move around the site?

Where will work be staged?

Material and spoils storage

Maintenance and fueling areas

Delivery truck access and traffic issues?

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Construction Sequence

Water control

Foundation construction Drilling

Concrete forming

Channel demo and grading

False work/deck forming

Pre-stressing/curing

Installation

Approaches

Erosion control

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Construction Inspections

Inspections are very important - use construction inspection forms

Extensively photograph work progressing

Inspection Milestones:

Staking and job layout

After clearing and grubbing, new topo may be taken to estimate quantities

After rough grading

During rock placement/willow staking

During LWD/in-stream structures placement

Check step pool elevation and depths as you go!!

After erosion control installation; during and after planting and irrigation installation