Wilma Dykeman Riverway Road Intersection Re-modernization

Project team: M. Dooly J. EnsleyS. EscobarD. KestnerJ. LovelaceL. RoselliT. Wyatt

Design a Modern Roundabout for the Three leg intersection of: Amboy Rd Meadows Rd Lyman Rd

Design a Vehicular Bridge or

Refurbish Existing Bridge to

Accommodate Increased

Vehicular Traffic as well as

Pedestrian and Bicycle Traffic.

Roadway Connection at or near the Proposed Roundabout for direct access

to Asheville-Buncombe Technical Community College.

ASHTO

USGS NCDOThttp://www.ncdot.org/travel/statemapping/default.html

Steel Design Text Book Reinforced Concrete Design Textbook

Buncombe County› http://www.buncombecounty.org/Governing/Depts/GIS

United States Department of Agriculture› http://websoilsurvey.nrcs.usda.gov/app/

“UP YONDER WAY”

BRIDGE DESIGN

Dillon Kestner

DESIGN METHODOLOGY

Evaluation of current intersection of Amboy/Meadows Roads

Evaluation of existing bridge over French Broad River

Existing Bridge and intersection

DESIGN METHODOLOGY

Evaluation of current intersection of Amboy/Meadows RoadsExisting intersection causes excessive traffic queuing and delays onto the Bridge/Amboy Road as well as traffic coming from Biltmore Ave onto Meadows Road

Evaluation of existing bridge over French Broad RiverIn need of remediation if not removalPoor pedestrian facilitationBottleneck to proposed 4-lanes of Amboy Road in the feasibility study

Existing bridge does not have a walkway but pedestrians daringly still try to use the 2 foot wide curb.

The Riverway Project demands a more pedestrian/bicycle friendly bridge and intersection in this area to link the rest of the parks and walkways along the river.

The traffic volume projections for 2025 (24000 vehicles per day versus the current 16000 vehicles per day from 2004 estimates) indicate that a 4-lane rather than 2-lane bridge would accommodate this flow of traffic as well as be a more cohesive design with the proposed 4 lanes of Amboy Road.

A 4-lane bridge over the French Broad calls for a new intersection.

WHAT SHOULD A NEW BRIDGE FEATURE?

It should provide better traffic flow to and from

Amboy Road.

It should have pedestrian traffic facilities.

Its design should be cohesive with the proposed

Amboy Road alignment.

It should have few negative impacts on the

surrounding park areas or the French Broad River.

It should be aesthetically pleasing and reflect the

spirit of the River Arts District.

The Alternatives Considered:

• Rehabilitation of current bridge/intersection

• Construction of New Bridge only

• Construction of New Intersection only

• Construction of New Bridge with Roundabout

Intersection

• Do Nothing

Focus on alternative to construct a new bridge and

roundabout intersection

A ROUNDABOUT IS A MORE MODERN INTERSECTION THAT

CAN HELP TO EASE CONGESTION ON AMBOY/MEADOWS

ROADS

Key Features:

•High capacity

•Safer than signalized

intersection

•Low delay times

•More on Roundabouts

Later!

DECISIONS BEFORE DESIGN

A new bridge should be constructed while existing

bridge is still in operation for better traffic mitigation.

Design should be cohesive with Amboy Road and

aesthetically pleasing.

Design should not effect river channel dramatically.

New bridge will operate while existing bridge is

removed for construction of another bridge making

the total 4 lanes.

BASIC CROSS SECTION OF BRIDGE

Lane width at 11 ft for continuity with proposed

Amboy Road alignment

2 lanes each direction

18 inch curb and gutter outside travel way

60 inch side walk outside travel way

Aluminum parapet railing along sidewalk for

traffic/pedestrian safety

ALUMINUM PARAPET

Weight savings advantage over steel/concrete

No need to treat for weather corrosion

Higher than steel initial cost but much lower maintenance cost

Roundabout and 2D New Bridge Drawings over GIS Image

New Bridge Alignment with Roundabout

Image Drawn in 3D showing ground surface

Image Drawn in 3D showing ground surface

Image Drawn in 3D showing ground surface

Conceptual Rendering

ALTERNATIVES TO CONSIDER

5 foot median between sides of bridge can be

mulched and flowered for beautification

purposes, or parapet divided.

Sidewalks can be tied into facilities on Amboy and

Meadows Roads and to the park not shown in

Rendering.

Bridge section could be widened to better

accommodate cyclists that do not use sidewalks.

ALTERNATIVES TO CONSIDER

Steel members and Piers analyzed for current span

lengths but larger members can be considered to

increase span lengths and reduce any negative

impacts on the French Broad River.

NEXT PHASE PLANNING

Evaluation of concrete reinforcement

Pier installation feasibility in river

Bolted/welded connection analysis

Impacts on local wildlife and park areas

Presented By: Truman Wyatt

General Terminology

Comparison of Traffic Circles

Applications and Examples

General Information

Many misperceptions

Not simply a circular intersection

Roundabouts Include:◦ Yielding at entry

◦ Low speeds due to the curve

◦ Designed precisely based on peaked traffic volumes

Slowing Down/Calming Effect

Very Safe

Low Maintenance Cost

Easily Modified

Eliminates Red lights

Good Traffic Operations/Few Delays

Concepts almost identical to traffic signals

Pavement Markings will guide you

SELECT YOUR LANE BEFORE THE YIELD LANE

YIELD TO TRAFFIC WITHIN CIRCLE

LEFT TURNS ARE MADE FROM THE LEFT (inside) APPROACH LANE

Circle

Truck Lane

2, 12ft lanes w/ 5 ft bike lane

Amboy Rd.

Meadow Rd.

Lyman Rd.

Pedestrian Bridges

Proposed Pedestrian Bridge Location

Types of Pedestrian Bridges

Types of Pedestrian Bridges

Types of Pedestrian Bridges

Proposed Pedestrian Bridge

J O N A T H A N L O V E L A C E

Proposed AB Tech Bridge/Roadway

Preliminary Data

AB Tech Growth

Annual student growth of 8.2%

Annual Faculty growth of 21.8%

ADT

17, 500 (2010)

75,000 (2025)

20% added for business traffic

Proposed Road Design

Turning Bay

2010 – 175 ft.

2025 – 500 ft.

Calculated by 25 ft bumper to bumper distance

2000 ft allowable

Specifications

Four lanes

Currently two lanes are needed

Non divided

Double Yellow, no turning lanes

1176 ft. traffic circle to proposed Lyman Rd. intersection

3500 ft. Lyman Rd. to AB Tech intersection (Behind Maple)

Proposed Road Design Cont.

Next phase planning

Cut and fill

Switchbacks

Currently placed to grade

radius to small for 4 lane road

Tie in point at intersection of AB Tech campus

4 lane to 2 lane

Currently road between 3% and 7% grade

Topo survey needed to obtain proper grade

Landscape buffering between road and residential properties

Proposed Bridge to A-B Technical C.C.

Proposed AB Tech Bridge

Design Specifications

240 Ft Bridge span

Minimum height 26 ft.

With in specifications for railroad crossing

Allowed for two tracks on either side of previous tracks

Next phase planning

Currently 9% grade from bridge to Lyman Rd intersection

Approximately 20 ft of fill needed to obtain reasonable grade

Bridge Piers

Bridge Gerters

Proposed Bridge location to A-B Tech C.C.

Proposed Bridge to A-B Tech C.C. Over Rail Road Yard

Preliminary Soil StudyFrom the United States Department of Agriculture

Jared Ensley

Amboy Bridge

Soil Report• Sandy Clay soil

• Requires certain depth

• Assumptions made, need to be reviewed at next stage

• If replacement needed, soil cut could be placed

Abutments

• Mechanically Stabilized Earth

(MSE)

• Drilled Shaft

http://www.sr85-123.com/gallery_past.php

Mechanically Stabilized Earth Abutment

Pros:

• Earthwork is usually cheaper

• Speed of construction

• Multiple contractors may be

used

Cons:

• Excavated soil would be

wasted

• Reusable soil would need to

be stored off site temporarily

http://www.berlinvt.org/1057-01%20Report.pdf

Drilled Shaft Abutment

http://northwest.construction.com/northwest_construction_news/2010/1001_DBMCompletes.asp

Pros:

• Limited excavation

• As long as it is placed in the

bedrock, no rehabilitation needed on

back slope

Cons:

• Auger cuttings would likely be

wasted

• More expensive than MSE

abutment

http://www.berlinvt.org/1057-01%20Report.pdf

Bridge to AB-Tech

Soil Report• Loamy Clay Soil (fill)

• Good base

• Assumptions made

• More testing needed

Hydrology & Hydraulicsfor

Bridge Design

Bridge Design Objectives

Provide for the safe traveling of the public across a waterway.

Allowing for transportation of storm discharges through the structure without impacting the traveling public, damage to properties or the environment.

Real-Time Water Data for French Broad Watershed

Asheville Flood, 2004

FRENCH BROAD RIVER AT ASHEVILLE, NC

Daily stream flow Avg.;

(Min) (Max)

2,420 (ft3/s) 3,050 (ft3/s)

Peak Runoff (existing)

StreetName

Length,(FT) Width,(FT) Incl. sidewalk

Runoffcoefficient

RainfallIntensity, in/h

Peak runoff

Amboy 3,320 24 .95 7 530,000

Meadows 3,004 24 .95 7 480,000

Lyman 1,400 24 .95 7 220,000

Total. 1,200,000(cfs)

Peak Runoff (proposed)

StreetName

Length,(FT) Width,(FT) Incl. sidewalk

Runoffcoefficient

RainfallIntensity, in/h

Peak runoff

Amboy 3,320 68 .95 7 1,500,000

Meadows 3,004 68 .95 7 1,400,000

Lyman 1,400 44 .95 7 400,000

Total. 3,000,000(cfs)

Peak Runoff (comparison)

Proposed 3,000,000(cfs)

Existing 1,200,000(cfs)

An addition of 1,800,000 cfs

•37% more runoff then existing road.•3,000,000 cfs can fill a basketball court 10 feet high in 1 min.

Storm Water

Increase of 60-75 percent of impervious area due to lane widening and proposed design.

Probably exceed design criteria for current storm water removal.

Removal to be evaluated in the next phase.

Hydraulic Consideration for Bridge design

Scour

Bank

Piers

Backwater elevation change

Scour

Recommended Prevention Methods

Rip Rap (Piers and Bank)

A-Jacks (Piers only)

Further detail in the next phase

Placement

Size

Amount

Scour Prevention

Design for Scour Prevention Round piers were chosen

Round piers allow a smoother transition of flow around pier

Creates less backwater elevation

Bridge Requirements

Any other structures located within the Downstream

and Upstream survey limits should be surveyed like

the project structure

Any sharp bends, head cut, or significant changes in

the stream channel or floodplain within the survey

limits should also be surveyed.

Channels that are flatter than 0.0004 ft/ft requires an

additional cross section at 4000 ft. downstream of the

Bridge.

Allowable Backwater

• In general, the bridge should be designed to clear thedesign frequency flood

• Meet NFIP (National Flood Insurance Program)requirements

• Limited to 1-foot raise in 100-year backwater

• Backwater should not be allowed to flood “Unreasonably large areas of usable land”

• Backwater should not be increased in urban areas

BRIDGE DESIGN CRITERIA:

Bridge was design to pass the 100 year

storm with 2 feet of freeboard.

There should be no impact to the

upstream water surface elevation or

floodway.

Preliminary estimates:

New Vehicular Bridge Construction OverFrench Broad: $5,068,000

Removal of Existing Bridge: $483,000

New Pedestrian Bridge: $1,350,000

Roundabout Construction: $1,750,000

Total Construction Cost of $8,651,000