Noise Barrier Graphs

NACs

Average Noise Reduction by Decade and Surface Texture
Surface Texture	1960-1969	1970-1979	1980-1989	1990-1999	2000-2009	2010-2019	2020-2023	Average
Absorptive	-	8.0	-	8.4	7.7	7.4	7.3	5.25
Reflective	-	8.2	7.3	7.9	6.8	7.1	6.9	6.22
Both	-	-	-	-	-	9.2	7.6	1.53
Not Reported	-	-	9.5	7.0	6.4	6.6	7.1	4.92

Pre-2013 data is low quality due to how few values are reported compared to how many barrier/rows there are
For barriers without a year or surface texture, the average noise reduction was 10.5 dB

Average Noise Reduction by Surface Texture
Surface Texture	2013	2014	2015	2016	2017	2018	2019	2020	2021	2022	Average
Absorptive	6.9	7.3	7.9	7.4	6.6	7.7	7.9	7.0	7.2	7.8	7.4
Both	No data	8.0	6.0	8.6	No data	8.3	No data	5.0	8.4	7.5	7.4
Reflective	7.3	6.8	7.3	6.8	7.0	7.4	7.2	6.8	6.8	7.1	7.1
Not Reported	6.4	5.1	5.3	5.3	6.2	8.0	7.8	7.3	6.7	7.2	6.5
Average by Year	6.9	6.8	6.6	7.0	6.6	7.9	7.6	6.5	7.3	7.4	7.1

Data for 'Both' is very sparse and sometimes based on a single value
Does not include any barriers that reported a Surface Texture without a Year.
For barriers without a year or a surface texture the average noise reduction was 10.5 dB

Square Footage of Barrier by Activity Category and Year Built
NAC Category	2013	2014	2015	2016	2017	2018	2019	2020	2021	2022	Total
B	6,708,433	6,120,180	6,416,285	10,456,906	3,442,504	6,618,568	9,843,810	8,780,319	4,666,969	8,148,619	71,202,593
C	489,301	1,170,648	482,494	802,654	351,228	592,678	3,237,739	585,457	1,034,361	1,521,195	10,267,755
D	5,936	171,526	86,900	64,284	4,696	87,955	117,370	-	-	-	538,667
E	317,032	141,176	64,262	315,583	66,730	909,025	389,612	175,792	135,830	804,887	3,319,929
No criteria selected		428,269	201,822	187,668	63,318	608,449	177,727	203,542	132,540	292,812	2,296,147
Total	7,520,702	8,031,799	7,251,763	11,827,095	3,928,476	8,816,675	13,766,258	9,745,110	5,969,700	10,767,513	87,625,091

Totals columns under the years do not add up to be the same as the Master Table because some barriers are listed as protecting multiple NACs
Total NAC B without year is 498,442 sq ft
Total NAC C without year is 78,790 sq ft
Total without NAC or Year is 8,180,990 sq ft

Average Noise Reduction by Material
Primary Construction Material	Reduction
Berm	6.4
Block	6.1
Brick	6.0
Cast-in-Place Concrete	7.0
Metal	7.5
Precast Concrete	7.3
Wood	8.1
Combination	7.9
Other	6.9
Unspecified Concrete	7.5
Unreported	7.8
Average	7.1

Other = Single-material barriers listing a 'Primary Const. Material' of Acrylic, Acrylite, Carsonite, Composite, Durisol, Fiberglass, Glass, Other, Plastic Opaque, Plastic Other, Plastic Transparent, PVC, Rubber
Unreported includes barriers that only reported a 'Secondary Construction Material', and those that reported no materials at all. Also includes a barrier that reported 'N/A' for the material, and another that said 'Not Masonry Block'; both in the 2020-2022 collection.
Combination includes all barriers listed as 'Combination', include 'Combination' in the material type name, or that list both a Primary and a Secondary Construction Material.
* Berm, Brick, Wood, Unreported have very few data points; the rest are missing half or more of their entries

*Other Materials:
Primary Construction Material	Reduction
Acrylic/Acrylite	6.8
Carsonite	8.3
Composite	8.4
Durisol	8.9
Fiberglass	6.3
Glass	6.4
Plastic Opaque	7.0
Plastic Transparent	7.2
PVC	No data
Rubber	6.5
Undefined 'Other'	5.0
Average	7.1