Precast Concrete Noise Barrier Walls for New Jersey Interstate Route 80

Fuat Guzaltan, P.E. Supervising Structural Engineer Parsons Brinckerhoff-FG, Inc. West Trenton, New Jersey

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An improved design of a precast concrete noise barrier wall, comprised of posts spaced at 15 ft (4.57 m) on centers and drop-in panels, represents a cost effective, long lasting and aesthetically pleasing solution to mitigating the effects of highway noise on adjacent residential communities.

I n the summer of 1987, as part of the ongoing design effort for widening Interstate Route 80, Section 8M,

Morris County, the New Jersey Department of Transportation decided to include noise abatement measures in the project. These measures con­sisted of earth berms and ground mounted noise barrier walls that also extended alongside the existing bridges spanning the local roads.

The project was comprised of 17,000 linear ft (5182 m) of precast concrete noise barrier walls with a total surface area of 345,000 sq ft (32100 m2

). Also included were four special structures to carry the noise barrier walls alongside the existing expressway bridges.

Due to the successful outcome of this project, the same design approach was implemented in an adjacent sec­tion of Interstate Route 80. In this new section, a similar type of construction is being utilized on a much larger scale to include 35,000 linear ft

(1 0,670 m) of noise barrier walls with a total surface area of 752,000 sq ft (70,000 m2

) and six independent noise barrier structures.

Conceptual designs for the noise barrier walls were prepared for two alternative materials, wood and con­crete, as directed by the Department's Bureau of Environmental Analysis and Bureau of Landscape Architec­ture. Our recommendation was for the concrete alternative on the basis of durability, cost effectiveness, aesthet­ics and conservation of forests . How­ever, both concepts were presented to the residents of Morris County at a public meeting in December 1987.

At this meeting, the area residents overwhelmingly opted for the concrete noise barrier walls. The durability and aesthetics of concrete were the reasons cited by the public. In compliance with public opinion, we proceeded with the noise barrier wall design using concrete as the primary material.

The extensive use of precast con-

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Photo 1. Precast concrete posts and panels provide a durable and aesthetically pleasing appearance.

Photo 2. Overview of precast concrete noise barrier wall.

July-August 1992 57

Photo 3. Independent steel frame structure alongside bridge awaits installation of lightweight concrete noise barrier panels.

crete components in the noise barrier walls provided a cost effective, long lasting and aesth~tically pleasing solution to an environmental prob­lem. Several events during the 'pro­ject development confirmed the superiority of precast concrete over other materials and construction methods:

• Communities situated along the pro­ject site overwhelmingly preferred precast concrete walls over the tim­ber walls.

• When an alternate design using steel posts was included in the contract documents of the adjacent section,

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none of the 11 contractors bid on the steel alternate.

• After experimenting with the cais­son foundations and cast-in-place spread footings, which was given as a design alternative, the contractor decided to use precast concrete spread footings in order to lower the cost and to meet the tight project deadlines. Two challenges were encountered

during the course of design: The first challenge was the develop­

ment of design criteria for application of the wind forces on noise barrier walls. When we initiated the design in

1987, there were no established design criteria for noise barriers as they exist today (i.e., AASHTO Guide Specifications for Structural Design of Sound Barriers). Using ASCE Paper No. 3269, Final Report on "Wind Forces on Structures," and "AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Sig­nals," we developed criteria encom­passing the dynamic and static aspects of the design.

The second challenge was the development of a structural system that would carry the noise barrier walls alongside the existing bridges. A detailed analysis determined that the existing bridges could not carry the noise barrier walls without replacement of one or two lines of existing beams. The cost and the time involved, plus the potential for traffic disruptions, ruled out this option.

After a detailed comparison of sev­eral structural systems, a steel and concrete support system emerged as the most practical and economical solution. This system supported the lightweight precast concrete panels on a steel Vierendeel shaped double truss on steel towers (see Fig. 1). For the sake of economy and aesthetics, the steel towers were terminated at the level of existing bridge substructures. At this level, the towers were sup­ported on reinforced concrete ped­estals founded either on spread foot­ings or pile foundations.

The reinforced concrete pedestals were carefully detailed to blend in with the existing piers, abutments and wingwalls. There were four such structures along the length of the pro­ject, with spans varying from 75 to 175ft (22.9 to 53.3 m).

A typical ground mounted noise barrier wall (Fig. 2) is comprised of reinforced precast concrete posts spaced at 15 ft ( 4.57 m) on centers with 5 in. (127 mm) thick drop-in reinforced concrete panels each, 2 or 4 ft (0.61 or 1.22 m) high and 14 ft 2 in. (4.31 m) long. Wall heights var­ied from 8 to 30ft (2.44 to 9.14 m). Changes in ground elevations were accommodated by 2 to 4 ft (0.61 to 1.22 m) drops or rises in wall heights.

Fig. 3 provides typical foundation

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Photo 4. A three-span independent noise barrier structure supports lightweight concrete panels alongside an existing bridge.

Photo 5. Precast concrete spread footings for noise barrier walls await installation.

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TWIN VIER ENDEEL TR USS

STEEL TOWER --- +-t-- --1

REINFORCED

CONC RETE PEDESTA l

I I

-----PRECAS T LIG HTWEIGHT CONCR ETE NOISE BARRIER PANE L

PAINTED MET A L CLOSU RE DEVIC E BE TWEE N PANEL AND BARRIE R CU RB

2'·10" BARRIER CURB

BRIDGE DECK SLAB

EXIST ING PIER / AB UTMENT

REIN FORCED r __ L ____ ___ j CONCR E TE FOOTING'i--- 1- - --- ---------•u ; --., I

1 I L _____ _ ____ .J _______________ _

Fig. 1. Typical section of an independent noise barrier structure.

and post detai ls of the noise barrier wall system. Table I gives the number and dimensions of the precast concrete components.

A total volume of 15,000 c u yds (1 1545 m3

) of concrete was used to

complete the entire length of the noise barrier wall s. Out of this total , 7800 cu yds (5964 m3

) of concrete were used to manufacture the precast concrete posts and panels. Approxi­mately two-thirds of the spread foot-

Table 1. Number and dimensions of precast concrete components.

1152 Precast Concrete Posts - I-shaped sections with 18 x 21 in. and 21 x 24 in. d.imen-sions, and lengths varying from 13 to 35 ft

6347 Precast Concrete Panels -5 in. thick and 14 ft 2 in. in length, 2 or 4 ft in height

760 Precast Concrete Spread Footings - Footing sizes range from 4 ft x 6 ft 9 in. to 8ft 6 in. x 17ft, and the weight varies from 6 to 35 tons

Note: I ft = 0.3048 m; I in. = 25.4 mm; I ton = 0.907 t.

ing foundations were built as precast units.

A detailed subsurface soils explo­ration program revealed the presence of glacial deposits, mostly boulders. This discovery led to the design of two foundation types, providing the con­tractor with fle xibil ity in his opera­tions. An augered caisson foundation was proposed for the areas where no boulders would be encountered, and a spread footing option was given as an alternate for areas where boulders would be present.

HORIZONTA PAN E LS TO !"VER T. TO

L JOINTS I N I 1s '- o " 't_ PRECAST CONCRE T E POST ( T YP. ) LINE UP WIT HI N

_I L ERANCE ITY P.)~

, .,,,,,.~ ;\:"'""'' INSERT I TYP )

I N MIN. 0 " MAX 1" ITYP l 1-~ROP IN WALL HE IGHT I USE 0', 2' OR 4 '

I II~ I

I

!~ ~ r I I I

5 INCH THICK PRECAST I II

CON CRETE PANEL

I ! j l

~ II I J 6 " MIN SOIL COV ER I I II ITYP.l I I ~ - EXISTING AND PROPOS

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/ I I II ~

I I 11 l! i " ~

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ED GROUND

ER IC BEARING PAD_j ~ · ·V ' 1· ·. ~ ~ :· lifT ...,__

TYPICAL STEP IN FOOTING~ < 1~1 i · :lfl· :lt· · TO ACCOMMODAT E CHANG ES I TYP J . · r · 'I·~ IN GROUND ELEVAT ION

<~i~~: (USE 0 ', 2 ' OR 4 ' l ~: " li'l 'f l : ~ . . . . ' II ~ . ~ ;. ll l l ' l["

:.;.: ~~ l :l~ ~~)---POST FOUN DAT IO N

~ :k!J:.u::

EL ASTOM

•.• .:t :•.:

Fig. 2. Typical elevation of ground mounted noise barrier wall.

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~ PRE CAST CONCRETE POST

6" MIN SOIL COVER ITYR I

VARIESISTEPAT LOCATIONS tt-:1===t------t OF DROP IN WALL I

3000PSI CONC RET E

~5 .. I

N

18"

8 " WEB

CA I SSON

WALL HEIGHT ~ 2 4F T.

5'·0 " EMBEDMENT (ROUGHEN PERIPHERY OF PRECAST POSTl

;TYP.)

FOOTING REBARS

NOlO BAR ITYR I

26F T . ~ WALL H E I GHT~ 32 FT.

Fig. 3. Typical foundation and post details of a ground mounted noise barrier wall .

A 5000 psi (34.5 MPa) concrete was used in the fabrication of the precast posts and panels. The posts were 1-beam shaped and reinforced with Grade 60 reinforcing bars. The panels were 5 in. (127 mm) thick and reinforced with wire mesh and Grade 60 reinforcing bars. Special cast-in­place lifting inserts were used in all precast units to minimize damage during handling and installation of the units.

Aesthetics was a primary concern in the detailing of the noise barrier walls. To enhance the appearance of

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the barrier walls, the posts and road­way side of the wall panel s were finished smooth, while a textured fin­ish was applied on the residential side of the panels to accentuate the contrast between posts and panels . Furthermore, an adobe colored stain was applied to all precast concrete elements to achieve harmony with the existing suburban landscape.

To ensure proper fit and harmony between panels and posts, the precast elements were constructed to PCI tol­erances. Panel joints and panel-to­post connections were detailed to

SPREAD FOOTING

NO 4 AT 12 " (TY RI

34FT . ~ WALL HEIG H T ~ 38FT.

ensure proper fit, ease of construction and long lasting performance.

The precast concrete components were transported by truck from the precasting plant to the site where they were easily installed with a minimal disruption to traffic and other con­struction activities.

Photos 1 through 7 show noise barrier walls in various stages of construction.

The project was finished in October 1991. The total cost of the noise bar­rier wall project was $5 million. The approximate cost for the ground mounted noise barrier walls was $18

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3-NO.G BARS

( TYf' EA. FAClE_:_I ~\ (-,;i;=p~;p;;;;;-+:t;;i::t

"' w a: <[ >

VERTICAL RE BARS

CROSS SECTION

Fig. 4. Typical anchored foundation detail.

STEP TO ACCOMMODATE 1'- 9" ft. PRECAST CONCRETE POST CHANGES IN GROUND \1----'--"--f-'::..._:=:..:..:..::...:_===c--=--c---'-''-' ELEVATION EXISTING AND

TO BE FILLED WITH NON-SHRINK CEMENT GROUT

.... z w

x ::!' <[ a

w "' ::!' CD

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;<:: 0 "-

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\ PROPOSED GROUND

II ,, I I II I I II I I u

3"MIN . ib DRILLED HOLE

1 I TO BE GROUTED ( TYP. I II :

1 EPOXY COATED ROCK : 1 ANCHOR ( TYP. I u

Photo 6. Raked finish on the residential side of the noise barrier wall creates a contrast with the smooth finish of the precast concrete posts.

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Photo 7. Overall view of the noise barrier wall shows its successful integration with the existing suburban landscape.

per sq ft ($194/m2) including panels,

posts and foundations. The cost for the independent noise barrier structures was $88 per sq ft ($945/m2

) including panels, steel superstructures and con­crete substructures.

The noise barrier wall adjacent to the Section 8M project is currently under construction. The total cost of the noise barrier walls will be $15 million. This latter project is scheduled for comple­tion in 1993.

A unique feature of the project is the use of anchored foundations at locations

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where rock layer is close to the surface.

A typical anchored foundation (see Fig. 4) is comprised of a cast-in­place reinforced concrete footing and four Grade 150 post-tensioned rock anchors.

The rock anchors have lengths varying from 20 to 27 ft (6 to 8 m) and are installed in 3 in. (75 mm) diameter holes filled with non-shrink cement grout. Approximately 105 anchored foundations are scheduled to support the noise barriers in the rocky areas.

Credits

Owner: New Jersey Department of Transportation, Trenton, New Jersey

Design Engineer: Parsons Brincker­hoff-FG, Inc., West Trenton, New Jersey

General Contractor: Bellezza Com­P!lJlY, Inc., South Kearny, New Jersey

Precast Concrete Manufacturers: -Concrete Safety Company,

Bethel, Pennsylvania (Posts and Panels)

- J. DiSanti Concrete Corp., How­ell, New Jersey (Spread Footings)

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