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Noise measurements at Hillside Place Housing Project, Westmount,
Quebec
NATIONAL RESEARCH COUNCIL OF CANADA DIVISION OF BUILDING RESEARCH
NOISE MEASUREMENTS AT HILLSIDE PLACE HOUSING PROJECT
WESTMOUNT, QUEBEC
by
T.D. Northwood and J . D . Q u i r t
P r e p a r e d f o r
C e n t r a l Mortgage and Housing C o r p o r a t i o n
I n t e r n a l Report No. 421 o f t h e
D i v i s i o n o f B u i l d i n g Research
O'ITAWA September 1975
PREFACE
An i n c r e a s i n g l y i m p o r t a n t n o i s e problem i s t h e d e s i g n o f b u i l d i n g s t o p r o v i d e a d e q u a t e sound i n s u l a t i o n from o u t - door n o i s e s , such a s a i r c r a f t , r a i l , and road v e h i c l e s . A s p a r t o f i t s work i n t h i s f i e l d , t h e D i v i s i o n h a s been
a s s i s t i n g C e n t r a l Mortgage and Housing C o r p o r a t i o n i n t h e development o f g u i d e l i n e s f o r s i t e p l a n n i n g and h o u s i n g
c o n s t r u c t i o n i n t h e v i c i n i t y o f a i r p o r t s , r a i l w a y s , and major roadways.
T h i s r e p o r t , i n a d d i t i o n t o d e a l i n g w i t h a s p e c i f i c problem o f road and r a i l n o i s e , forms a v a l u a b l e and t i m e l y example a g a i n s t which t h e g e n e r a l g u i d e l i n e s c u r r e n t l y u n d e r development can be a s s e s s e d . C . B. Crawford Ottawa September 1975 I l i r e c t o r D i v i s i o n o f B u i l d i n g R e s e a r c h , N a t i o n a l Research Council o f Canada.
1. INTRODUCTION
H i l l s i d e P l a c e i s a p u b l i c h o u s i n g p r o j e c t b u i l t by t h e C i t y o f Westmount t o accommodate f a m i l i e s d i s p l a c e d by t h e TransCanada Highway l i n k a t t h e s o u t h edge o f Westmount. The p r o j e c t c o n s i s t s o f s e v e n row- d w e l l i n g s t r u c t u r e s on a s m a l l p r o p e r t y a d j a c e n t t o t h e CPR main l i n e i n t o M o n t r e a l . Immediately s o u t h o f t h e r a i l w a y and on about t h e same l e v e l a s t h e r a i l w a y and t h e h o u s i n g p r o j e c t a r e t h e t h r e e westbound l a n e s o f t h e new s e c t i o n o f t h e TransCanada Highway. F u r t h e r s o u t h , down t h e h i l l , a r e t h e e a s t b o u n d l a n e s o f t h e highway, b u t t h e s e a r e n o t r e l e v a n t t o t h i s s t u d y . A s i t e p l a n o f t h e p r o j e c t i s shown i n F i g . 1. The s p a c e s between b u i l d i n g s a r e a l t e r n a t e l y p a r k i n g l o t s ( l a b e l l e d P i n F i g . 1 ) and g a r d e n a r e a s .
The p r o x i m i t y o f t h e highway and r a i l w a y t o t h e p r o j e c t
--
c l o s e r t h a n p e r m i t t e d by CMHC s e t b a c k r e q u i r e m e n t s - - r e s u l t s i n a v e r y n o i s y environment. The purpose o f t h i s s t u d y was t o measure t h e n o i s e a n d t o a s s e s s i t s a c c e p t a b i l i t y f o r r e s i d e n t i a l p u r p o s e s . A s t h e o b s e r v e d l e v e l s were s u b s t a n t i a l l y h i g h e r t h a n would n o r m a l l y b e a c c e p t e d , con- s i d e r a t i o n was a l s o g i v e n t o ways o f r e d u c i n g t h e n o i s e .2. NOISE CRITERIA
The f o l l o w i n g remarks a r e b a s e d on g u i d e l i n e s now b e i n g develop- ed f o r r e s i d e n t i a l c o n s t r u c t i o n n e a r m a j o r roadways and r a i l w a y s . They a g r e e c l o s e l y w i t h s i m i l a r g u i d e l i n e s i n u s e o r proposed e l s e w h e r e . Three c r i t e r i a , b a s e d on t h r e e k i n d s o f r e s i d e n t i a l a c t i v i t y , a r e c o n s i d e r e d :
( I ) i n bedrooms a t n i g h t , maximum l e v e l s s h o u l d n o t be s o h i g h a s t o i n t e r f e r e w i t h s l e e p ; (2) i n o t h e r f r e q u e n t l y o c c u p i e d s p a c e s , such a s l i v i n g and d i n i n g rooms, t h e g e n e r a l n o i s e l e v e l s h o u l d b e low enough t o p e r m i t e a s y c o n v e r s a t i o n , l i s t e n i n g t o r a d i o o r t e l e v i s i o n and s i m i l a r q u i e t o c c u p a t i o n s ; ( 3 ) t h e r e s h o u l d b e a s h e l t e r e d o u t d o o r s p a c e ( p a t i o o r b a l c o n y ) where a t l e a s t i n t e r m i t t e n t c o n v e r s a t i o n i s p o s s i b l e .
For complex n o i s e s p e c t r a c o n t a i n i n g a wide r a n g e o f f r e q u e n c i e s it i s u s u a l t o u s e a f r e q u e n c y - s e l e c t i v e c i r c u i t known a s "A-weighting," which emphasizcs t h e middle- and h i g h - p i t c h e d components i n t h e complex sounds i n v o l v e d . These a r e t h e components t h a t i n t e r f e r e most w i t h s p e e c h and t h a t g e n e r a l l y c o r r e l a t e w i t h annoyance. A-weighted l e v e l s a r e u s e d t h r o u g h o u t t h i s r e p o r t . For f l u c t u a t i n g sounds such a s t r a f f i c n o i s e it i s a l s o n e c e s s a r y t o d e c i d e on some measure o f t h e t t a v e r a g e " e f f e c t o f t h e n o i s e . One o f t h e most s u c c e s s f u l measures i s t h e " e q u i v a l e n t l e v e l , "
(Le4), which i s t h e l e v e l o f a s t e a d y n o i s e t h a t would c a r r y t h e same t o t a l (A-weighted) sound e n e r g y . For problems such a s s l e e p a r o u s a l , how- e v e r , i t i s p r e f e r a b l e t o employ some measure o f s h o r t - t e r m - p e a k l e v e l ,
cLmax) '
I n t h e s e t e r m s t h e l e v e l s i n d i c a t e d i n T a b l e I a r e c o n s i d e r e d a p p r o p r i a t e maximum v a l u e s .
3. NOISE MEASUREMENTS ATHILLSIDE PLACE
The random f l u c t u a t i n g n a t u r e o f t h e n o i s e , c o n s i s t i n g o f high- way n o i s e w i t h r a i l w a y peaks superimposed, r e q u i r e s a r a t h e r complex measuring procedure. To compare l e v e l s a t two p o i n t s , f o r example, it i s n e c e s s a r y t o make simultaneous o b s e r v a t i o n s , averaged o v e r t h e same time i n t e r v a l . The complete n o i s e survey i n v o l v e d a s e r i e s o f such comparisons t i e d t o g e t h e r w i t h common r e f e r e n c e p o i n t s . The d e t a i l s o f t h i s p r o c e s s a r e g i v e n i n Appendix A .
A s t u d y of t h e temporal v a r i a t i o n i n n o i s e l e v e l was made by c o n t i n u o u s l y m o n i t o r i n g a t one p o i n t ( P o s i t i o n A , Fig. 1 ) . V a r i a t i o n s o f n o i s e l e v e l w i t h h e i g h t were a l s o examined a t t h i s p o s i t i o n . Varia- t i o n s w i t h d i s t a n c e from t h e n o i s y boundary ( t h e r a i l w a y f e n c e l i n e ) were examined mainly i n t h e garden a r e a between B u i l d i n g s 4 and 5 (comparing l e v e l s a t B , C , D i n F i g . 1 ) . Comparisons were a t t e m p t e d between t h e s e outdoor p o s i t i o n s and i n d o o r l e v e l s i n t h e bedrooms o p p o s i t e them ( i n U n i t s 106, 104, 102 o f B u i l d i n g 5 ) .
Comments on R e s u l t s
(1) The temporal s t u d y showed a marked d i f f e r e n c e i n c h a r a c t e r between daytime and n i g h t t i m e c o n d i t i o n s . T h i s i s mainly because o f t h e peaks i n t r o d u c e d by t r a i n s , which a r e v e r y i n f r e q u e n t d u r i n g t h e n i g h t . For t h i s r e a s o n t h e r e s u l t s a r e broken down i n t o daytime and n i g h t t i m e v a l u e s .
(2) S i n c e t h e r e i s a v a r i a t i o n i n n o i s e l e v e l w i t h h e i g h t , two h e i g h t s were used: f o r c o n s i d e r a t i o n o f n o i s e o u t d o o r s and i n g r o u n d - f l o o r rooms, t h e l e v e l a t 5 f t i s c o n s i d e r e d a p p r o p r i a t e ; i n d o o r measurements were made i n t h e s e c o n d - f l o o r bedrooms and compared w i t h o u t d o o r l e v e l s a t 1 5 - f t h e i g h t . L a t e r , i n t h e d i s c u s s i o n o f b a r r i e r s , a 2 3 - f t h e i g h t c o r r e s p o n d i n g t o t h i r d - f l o o r a p a r t m e n t s was c o n s i d e r e d .
(3) The e s s e n t i a l r e s u l t s , compiled a s d e s c r i b e d i n Appendix A, a r e given i n T a b l c 1 1 . Daytime v a l u e s a r e f o r t h e 16-h i n t e r v a l from 0700 t o 2300 h; n i g h t t i m e v a l u e s a r c f o r t h c remaining e i g h t hours.
4. DISCIISSION
I t i s o f i n t e r e s t t o compare t h c r e s u l t s shown i n l'ablc I1 with t h e recommended l e v c l s given i n Table I .
Because o f t h e d a y / n i g h t n o i s c v a r i a t i o n it i s c o n s i d e r e d t h a t daytime v a l u e s o f L
and Lmax a r e t h e b c s t i n d i c e s f o r t h e outdoor eq
p a t i o s and f o r t h e g r o u n d - f l o o r rooms ( l i v i n g , d i n i n g rooms). For bed- rooms, however, t h e n i g h t t i m e v a l u e s o f L
and Lmax w i l l be used. e q
( a ) Outdoor p a t i o a r e a s
T y p i c a l l e v e l s i n t h e s e a r e a s w i l l b e t h e r e a d i n g s a t 5 - f t h e i g h t a t P o s i t i o n s B , C and D. I t w i l l be s e e n t h a t L i s 10 t o 15 dB
eq t o o h i g h , and t h e daytime Lmax i s about 25 dB t o o h i g h .
(b) I n d o o r l e v e l s
Because o f t h e v a r i a t i o n w i t h h e i g h t i t i s e s t i m a t e d t h a t g r o u n d - f l o o r l i v i n g room/dining room l e v e l s w i l l b e 3 dB lower t h a n t h e bedroom v a l u e s . Hence i t a p p e a r s t h a t , w i t h t h e windows wide open, t h e i n d o o r L ' s a r e 12 t o 15 dB t o o h i g h . The v a l u e s o f daytime L a r e eq max a b o u t 30
d~
t o o h i g h . With windows t i g h t l y c l o s e d , v a l u e s o f L a r e e q s l i g h t l y bclow t h e r e q u i r e m e n t s g i v e n i n T a b l e I , b u t v a l u e s o f 'L (day- max time) a r e s t i l l 5 t o 10 dB h i g h e r t h a n recommended. I n bedrooms, c o n s i d c r i n g t h e n i g h t t i m e c o n d i t i o n , v a l u e s o f L e q w i t h open windows a r e a b o u t 15 dB t o o h i g h , and v a l u e s o f L a r e a b o u tmax
25 dB t o o h i g h . With windows c l o s e d t h e L i s s l i g h t l y below t h e r e q u i r e - e q
ment and L i s 5 t o 10 dB h i g h e r t h a n recommended. ma x
Summarv o f T e s t R e s u l t s
I t i s c o n c l u d e d t h a t t o make t h e H i l l s i d e P l a c e p r o j e c t a c c e p t a b l e from t h e viewpoint o f n o i s e , b o t h o u t d o o r and i n d o o r l e v e l s s h o u l d be reduced by a t l e a s t 10 dB, p r e f e r a b l y 15 dB. I n most r e s p e c t s t h e l e v e l s would t h e n approach t h e c r i t e r i a o f T a b l e I , a l t h o u g h some peak l e v e l s would s t i l l b e e x c e s s i v e .
5. REDUCTION OF NOISE BY MEANS OF A BARRIER
Ways o f a l l c v i a t i n g t h e n o i s c problem, now t h a t t h e p r o j e c t i s complctcd, ; l r c n o t c n s y t o f i n d . 'rhc most p r ; i c t i c a b l c method a p p c a r s t o bc n b a r r i c r Ijetwccn n o i s c s o u r c e s and t h c c r i t i c a l p o r t i o n s of t h e b u i l d -
i n g s . Thrcc p o s s i b l e b a r r i c r arrangcrncnts might be c o n s i d c r e d f o r r c d u c - t i o n o f n o i s c from highway and r a i l w a y .
To rcducc highway n o i s e one p o s s i b i l i t y would be a s o l i d w a l l o r f e n c e a t t h c edge o f t h e highway i t s c l f . A b a r r i e r o f moderate h e i g h t
would b e q u i t e e f f e c t i v e i n r e d u c i n g highway n o i s e r e a c h i n g t h e p r o j e c t , b o t h :it t h c ground l e v e l and a t t h e second- and even t h i r d - f l o o r l e v e l s . I t would n o t , however, r e d u c e t r a i n n o i s e ; i n f a c t i t might c a u s e a s l i g h t i n c r c a s e i n n o i s e due t o r e f l e c t i o n s back toward t h e p r o j e c t . Although o c c u p a n t s c u r r e n t l y a p p e a r t o b e morc d i s t u r b e d by t h c highway n o i s e it i s p r o b a b l e t h a t r e d u c i n g i t would a c c e n t u a t e t h e i r awareness o f t r a i n n o i s e .
Hence t h i s s o l u t i o n i s n o t pursued.
A b a r r i e r a t t h e f e n c e l i n e could a c h i e v e a s i m i l a r e f f e c t b o t h f o r highway and r a i l w a y n o i s e , b u t q u i t e a h i g h b a r r i e r would b e r e q u i r e d t o p r o t e c t t h e u p s t a i r s bedrooms and a p a r t m e n t s .
The t h i r d p o s s i b i l i t y i s t o p r o v i d e a s e r i e s o f b a r r i e r s l i n k - i n g t h e ends o f t h e b u i l d i n g s . S t r u c t u r a l l y , and perhaps a e s t h e t i c a l l y , t h i s p o s s i b i l i t y seems b e s t , - s i n c e t h e b a r r i e r could c o n v e n i e n t l y b e b u i l t t o any h e i g h t up t o t h e r o o f l i n e o f t h e t w o - s t o r e y s e c t i o n s . C a l c u l a t i o n s f o r a s e r i e s o f b a r r i e r s a t two l o c a t i o n s ( f e n c e l i n e o r l i n k i n g t h e b u i l d i n g s ) a r e g i v e n i n Appendix B. The r e s u l t s a r e summarized a s f o l l o w s : 1. A 1 2 - f t b a r r i e r a t e i t h e r l o c a t i o n p r o v i d e s adequate p r o t e c t i o n t o t h e outdoor garden a r e a s and t o g r o u n d - f l o o r rooms, b u t i n s u f f i c i e n t f o r t h e second- and t h i r d - f l o o r rooms.
2. A 1 6 - f t b a r r i e r a t t h e f e n c e l i n e p r o v i d e s m a r g i n a l l y s a t i s f a c t o r y p r o t e c t i o n a t s e c o n d - f l o o r h e i g h t s , b u t no improvement f o r t h e t h i r d
f l o o r . The same b a r r i e r h e i g h t a t t h e b u i l d i n g - l i n k l o c a t i o n would be s l i g h t l y l e s s e f f e c t i v e a t t h e second f l o o r .
3. A 2 0 - f t b a r r i e r a t e i t h e r l o c a t i o n would provide e f f e c t i v e p r o t e c t i o n a t t h e second f l o o r . Even a t t h e t h i r d f l o o r t h e r e would be a s i g n i f i c a n t improvement r e l a t i v e t o t r a i n n o i s e ; a s a consequence t h e daytime v a l u e s o f L and Lmax would be somewhat reduced.
eq
4. Roughly speaking, a 1 6 - f t b a r r i e r a t t h e fence l i n e p r o v i d e s n e a r l y a s much p r o t e c t i o n f o r t h e upper f l o o r s a s a 2 0 - f t b a r r i e r l i n k i n g t h e b u i l d i n g s .
Performance o f a 2 0 - f t Building-Link B a r r i e r
The e f f e c t o f a p a r t i c u l a r b a r r i e r can b e s t b e a p p r e c i a t e d by a p p l y i n g t h e i n s e r t i o n l o s s e s of Table B-I t o t h e observed l e v e l s g i v e n i n Table 11. Consider, f o r example, a 2 0 - f t b a r r i e r l i n k i n g t h e ends o f B u i l d i n g s 4 and 5,and examine t h e e f f e c t s i n t h e middle of t h e p r o j e c t , a t Unit 104 and P o s i t i o n C . In doing s o , i t should be noted t h a t daytime L a n d L m a x a r e l a r g e l y governed by r a i l w a y n o i s e ; on t h e o t h e r hand, t h e
c
n i g h t t i m c l c v c l s a r c govcrncd by highway n o i s e .
A t U n i t 104 t h c daytimc v n l u c s o u t d o o r s would b c reduced t o L = 49 and Lnlax = 71 dB A . Indoors a t ground l c v c l w i t h windows opcn
eq
t h e l e v c l s would be 36 and 59 dB A, r e s p c c t i v c l y . In t h e s e c o n d - f l o o r bedrooms w i t h windows open t h c nighttirnc l e v c l s would be L = 36 and
= 59 dB A. I n t h i r d - f l o o r a p a r t m e n t s c o r r e s p o n d i n g t o P o s i t i o n C , Lmax
w i t h windows open, daytime l e v e l s would be L = 40 and Lmax = 62 d ~ A
eq
r e l a t i v e t o t r a i n n o i s e ; however, highway n o i s e would be reduced l e s s and i n t h i s c a s e would p r o b a b l y govern, and t h e e f f e c t i v e l e v e l s might be a b o u t 45 and 67 dB A , r e s p e c t i v e l y . Nighttime l e v e l s i n t h e t h i r d f l o o r a p a r t m e n t would be L = 45 and Lmax = 61 dB A .
e q
I n sum, t h e r e s u l t s i n t h e middle o f t h e p r o j e c t would be t o b r i n g L e s s e n t i a l l y w i t h i n t h e c r i t e r i a o f T a b l e I up t o and i n c l u d i n g
e q
s e c o n d - f l o o r rooms. Values o f Lmax would s t i l l e x c e e d t h e c r i t e r i a . Some improvement would be g a i n e d f o r t h e t h i r d - f l o o r u n i t s , a l t h o u g h t h e l e v e l s would be s u b s t a n t i a l l y above t h e c r i t e r i a . S i m i l a r c o n c l u s i o n s can be r e a c h e d f o r a 1 6 - f t b a r r i e r a t t h e f e n c e l i n e . S p e c i a l C a s e s 1 . A p a r t i c u l a r l y s e v e r c problem e x i s t s a t t h e ends o f t h e b u i l d i n g s n e a r e s t t h e n o i s e . Here t h e n o i s e i s l o u d e s t and f o r t h e u p p e r f l o o r s t h e b a r r i e r s a r e l e a s t e f f e c t i v e . I f a b a r r i e r l i n k i n g t h e ends o f b u i l d i n g s i s i n s t a l l e d i t would b e h e l p f u l t o add t o i t a h i g h e r s e c t i o n where i t a d j o i n s t h i r d - f l o o r b a l c o n i e s . E s s e n t i a l l y t h i s would mean
e x t e n d i n g t h e e x i s t i n g p a r t i a l w a l l s forming t h e b a l c o n y . To a v o i d d a r k e n - i n g t h e b a l c o n y windows, a g l a z e d s e c t i o n , s a y one l a y e r o f 3/16 i n . g l a s s might b e i n c o r p o r a t e d . 2. P r o t e c t i o n o f t h e end b u i l d i n g s o f t h e p r o j e c t ( B u i l d i n g s 1 and 7) r e q u i r e s s p e c i a l a t t e n t i o n . B u i l d i n g 1 i s f a i r l y c l o s e t o a n o t h e r b u i l d - i n g , which would p r o v i d e p r o t c c t i o n a t l e a s t e q u i v a l e n t t o t h a t p r o v i d e d between a d j a c e n t u n i t s i n t h e p r o j e c t . Ilere i t would s u f f i c e t o e x t e n d t h e b a r r i e r t o t h e p r o p c r t y l i n e , w i t h a r c t u r n a l o n g t h e l i n e t o b l o c k t h e s i g h t l i n e s o u t h o f t h e a d j a c c n t b u i l d i n g . B u i l d i n g 7 i s exposed t o highway and r a i l w a y n o i s e o v e r i t s whole e a s t e r n f q a d e , and i t i s a m a t t e r o f judgemcnt whcrc t h c b a r r i e r s h o u l d end. I t i s s u g g e s t e d t h a t
;i f c n c e - l i n e b a r r i e r , i f uscd, s h o u l d f o l l o w t h c c a s t p r o p c r t y l i n c f o r
a b o u t 60 f t from t h e r a i l w a y f c n c c . A l t e r n a t i v e l y , a h a r r i c r from t h c b u i l d i n g cnd might s k i r t t h c c x i s t i n g p a r k i n g l o t and r c t u r n a l o n g t h e c a s t p r o p e r t y l i n e i n t h c same manner.
TABLE I . C r i t e r i a f o r r o a d and r a i l n o i s e i n and around d w e l l i n g s , dB Indoors :
-
bedrooms ( n i g h t t i m e )-
l i v i n g , d i n i n g , f a m i l y , r e c r e a t i o n rooms-
k i t c h e n s , bathrooms, a n c i l l a r y s p a c e s Outdoor p a t i o , balcony L max-
TABLE 11. Noise l e v e l s i n d o o r s and o u t d o o r s around Block 5 o f H i l l s i d e P l a c e dB
I
Locat i o n P o s i t i o n B ( s o u t h e n d , 22 f t from C P R f e n c e )-
1 5 - f t h e i g h t-
5 - f t h e i g h tI
P o s i t i o n C (67 f t from f e n c e ) - 1 5 - f t h e i g h t-
5 - f t h e i g h t P o s i t i o n D (112 f t from f e n c e ) - 1 5 - f t h e i g h t - 5 - f t h e i g h t I n d o o r s (bedrooms, f u r n i s h e d c o n d i t i o n ) U n i t 106, windows opcn U n i t 106, windows c l o s e d Unit 104, windows open Unit 104, windows c l o s e d U n i t 101, windows opcn Unit 101, windows c l o s e d(Note: L e v e l s i n l i v i n g and d i n i n g rooms w i l l bc a p p r o x i ~ n a t c l y 3 dB lower t h a n i n bcdrooms.)
APPENDIX A
DETAILS OF NO1 SE MEASUREMENTS
The mcasurcment program was o r g a n i z e d i n t h r e e segments:
(1) t e m p o r a l v a r i a t i o n i n o u t d o o r l e v e l ; ( 2 ) s p a t i a l v a r i a t i o n s i n o u t - door l e v e l ; and ( 3 ) l e v e l d i f f e r e n c e s o u t d o o r s t o i n d o o r s . The r e s u l t s w i l l b e d e s c r i b e d u n d e r t h e s e t h r e e h e a d i n g s .
Temporal v a r i a t i o n s
A c o n t i n u o u s g r a p h i c l e v e l r e c o r d and a c u m u l a t i v e s t a t i s t i c a l d i s t r i b u t i o n r e c o r d were made a t one p o i n t , a t t h e s o u t h end o f t h e p a r k - i n g l o t between U n i t s 5 and 6 ( P o s i t i o n A i n F i g s . 1 and 2 ) . The measur- i n g p o i n t was about 15 f t above t h e ground s o a s t o minimize l o c a l
s h i e l d i n g e f f e c t s . These d a t a i n d i c a t e t h e v a r i a t i o n i n n o i s e l e v e l w i t h t i m e , o v e r a b o u t a 21-h i n t e r v a l . To complete t h e 24-h p e r i o d an e s t i m a t e was made f o r t h e r e m a i n i n g t h r e e h o u r s .
Three t y p i c a l segments o f t h e l e v e l r e c o r d a r e shown i n F i g . A - 1 ; t h e d i u r n a l v a r i a t i o n o f L i s shown i n F i g . A - 2 .
e 'l
S h o r t - t c r m maximum l e v c l s wcre found by i n s p c c t i o n o f t h e g r a p h i c l c v c l r c c o r d . The r e s u l t s a r c summarized i n T a b l c A-I. Most o f t h c v a l u c s abovc 85 dB A a r c a t t r i b u t a h l c t o t r a i n s . Only one o f t h e s e
(86 dB A a t 11:20 p.m.) was o b s c r v e d d u r i n g t h e n i g h t t i m c p c r i o d . The r a n g e 80 t o 84 dB A i n c l u d e s b o t h r a i l t r a f f i c ( r a i l d i e s e l c o a c h e s ) and t r u c k p a s s h y s . Because t h e r a i l t r a f f i c o c c u r s a l m o s t e n t i r e l y d u r i n g daytime h o u r s , t h e r e i s a mark d i f f e r e n c c i n t h e d i s t r i b u t i o n o f peak l e v e l s hctwcen daytime and n i g h t t i m e . I t w i l l t h e r e f o r e b e a p p r o p r i a t e t o t r e a t t h e two p e r i o d s s e p a r a t e l y .
The v a l u e s o f L a r e b a s e d on o b s e r v a t i o n s o f t h e major peaks max
i n t h e daytime and n i g h t t i m e p e r i o d s . I n e a c h c a s e t h e t o p p e a k s , a t an a v e r a g e r a t e o f one peak p e r h o u r , were c o n s i d e r e d , i . e . t h e t o p 16 p e a k s f o r t h e 16-h daytime p e r i o d and e i g h t p e a k s f o r t h e n i g h t t i m e p e r i o d . An e n e r g y a v e r a g e o f t h e s e l e c t e d peaks was made t o d e r i v e an a v e r a g e v a l u e
Lmax i n each c a s e .
Thc r e s u l t s a t P o s i t i o n A ( 1 5 - f t h e i g h t ) , which c o r r e s p o n d a l s o t o P o s i t i o n 13 ( 1 5 - f t h c i g h t ) a r c summarized i n T a b l c A-I.
2. S p a t i a l v a r i a t i o n s i n n o i s c l c v c l
Dccausc o f t h c wide f l u c t u a t i o n s i n t h c n o i s c l c v c l i t i s n e c c s s a r y f o r comparison t o make s i m u l t a n e o u s measurcmcnts o v c r t h c samc t i m e i n t c r v a l . T h i s was done by t a p e r e c o r d i n g t h e s i g n a l s a t a s c r i e s o f p o s i t i o n s f o r l a t e r a n a l y s i s . The t o t a l s u r v e y was t h u s done i n a s e r i e s o f s t e p s , a s d e s c r i b e d below.
( a ) V a r i a t i o n w i t h Height. - A t P o s i t i o n A, measurements were made a t t h r e e h e i g h t s above t h e ground, i n c l u d i n g t h e 1 5 - f t h e i g h t used f o r t h e temporal s t u d y . T h i s h e i g h t i s a p p r o p r i a t e f o r comparison w i t h bed- room l e v e l s . For c o n s i d e r a t i o n o f l e v e l s i n t h e o u t s i d e p a t i o s a v a l u e c o r r e s p o n d i n g t o a h e i g h t o f 5 f t i s d e r i v e d . R e s u l t s a r e shown i n T a b l e A - 1 1 1 . These v a r i a t i o n s w i t h h e i g h t , d e r i v e d a t o n l y one p o i n t , a r e used i n e s t i m a t i n g l e v e l s a t o t h e r p o s i t i o n s ; it i s b e l i e v e d t h a t t h i s does n o t i n t r o d u c e s i g n i f i c a n t e r r o r . ( I n b a r r i e r c a l c u l a t i o n s it seemed a p p r o p r i a t e t o c o n s i d e r a l s o a h e i g h t o f 23 f t ; i t i s assumed t h a t n o i s e l e v e l s a t 1 5 - f t h e i g h t would be a p p l i c a b l e t o 23 f t . )
(b) V a r i a t i o n w i t h D i s t a n c e from Fence Line. - Measurements were made a t t h r e e p o s i t i o n s i n t h e s p a c e between Blocks 4 and 5 (B, C, D on Fig. 2 ) . For most o f t h e measurements t h e microphones were a t a h e i g h t o f approximately 5 f t . P o s i t i o n B i s s i m i l a r t o P o s i t i o n A r e l a t i v e t o t h e n o i s e s o u r c e s and i s t a k e n t o correspond i n a b s o l u t e l e v e l s t o P o s i t i o n A. Simultaneous measurements a t P o s i t i o n s B, C and D a r e t h u s r e l a t e d t o temporal measurements a t P o s i t i o n A . ( I t i s p o s s i b l e t h a t t h e p r o p a g a t i o n r u l e s a r e s l i g h t l y d i f f e r e n t f o r p a s s e n g e r c a r s , t r u c k s and r a i l w a y t r a i n s , b u t t h i s c o u l d n o t be i n v e s t i g a t e d h e r e ; t h e o b s e r v a - t i o n s a r e a n a v e r a g e f o r t h e t h r e e t y p e s o f s o u r c e . ) Levels a t P o s i t i o n s C and D , r e l a t i v e t o P o s i t i o n B, a t 5 - f t h e i g h t , were a s f o l l o w s : P o s i t i o n C , -2.7 dB P o s i t i o n D, -3.6 dB 3. Outdoor v s i n d o o r l e v e l s . Unit 104
Indoor l e v e l s i n t h e southwest bedroom o f Unit 104 were com- p a r e d w i t h o u t d o o r l e v e l s a t P o s i t i o n C (5 f t ) . Indoor l e v e l s were measured a t two p o s i t i o n s and f o r two t i m e i n t e r v a l s .in each c a s e . The mean l e v e l d i f f e r e n c e s were 3 . 8 dB f o r windows open and 24.1 dB f o r
windows c l o s e d . These r e s u l t s must be c o r r e c t e d by 3 dB t o c o r r e s p o n d t o t h e o u t s i d e l e v e l a t 1 5 - f t h e i g h t ( o u t s i d e bedroom windows). In a d d i t i o n , s i n c e t h e room i n 104 was u n f u r n i s h e d , a f u r t h e r c o r r e c t i o n o f 6 dB i s allowed f o r t h e a b s o r p t i o n provided by f u r n i s h i n g s . F i n a l l y , t h e d e r i v e d l e v e l d i f f e r e n c e s o u t s i d e (15 f t ) t o i n s i d e ( f u r n i s h e d bedroom) a r e a s f o l l o w s :
Level d i f f e r e n c e w i t h window open = 1 3 dB Level d i f f e r e n c e w i t h window c l o s e d = 33 dB. 4 . Indoor l e v e l s i n U n i t s 106 and 101
From r e l a t i v e o u t d o o r measurements a t p o i n t s B , C , and D, t o g e t h e r w i t h o u t d o o r / i n d o o r measurements a t Unit 104, one can e s t i m a t e t h e i n d o o r l e v e l s o v e r t h e l e n g t h of Block 5 . Some i n d o o r comparisons were a t t e m p t e d d i r e c t l y , b u t t h e s e were n o t e n t i r e l y s u c c e s s f u l because o f ambient n o i s e problems. One s u c c e s s f u l comparison, between 104 and
t h i s can be compared with t h e measured d i f f e r e n c e o f 2 . 7 dB between out- door P o s i t i o n s B and
C.
(A s i m i l a r comparison was attempted f o r t h e bed-room o f Unit 102, which was a v a i l a b l e i n l i e u o f 101, b u t t h e r e s u l t was low and t h e r e f o r e r e j e c t e d . )
5 , compilation of Table I 1 (Main Report1
The values o f
L
and Lmx a r e c o l l e c t e d i n Table 11as
follows.eq
The values f o r P o s i t i o n B ( 1 5 - f t h e i g h t ) a r e taken d i r e c t l y from t h e temporal s t u d y ( a t P o s i t i o n A ) . Data f o r t h e 5 - f t h e i g h t a r e d e r i v e d from t h e h e i g h t v a r i a t i o n r e s u l t s , which showed a decrease o f 3 dB from 1 s - f t d a t a . Data f o r P o s i t i o n s C and D a r e derived from P o s i t i o n B using t h e s p a t i a l v a r i a t i o n measurements. Indoor l e v e l s i n Unit 104 a r e d e r i v e d f r o m indoor/outdoor comparisions. Indoor l e v e l s from end t o end o f t h e b u i l d i n g ( U n i t s 106 and 101) a r e d e r i v e d from o u t s i d e measurements, supported by a d i r e c t comparison between 106 and 104 f o r t h e open-window condition.
TABLE A-I. Temporal d i s t r i b u t i o n o f peak l e v e l s , dB
Level a t Number o f Events
P o s i t i o n A Daytime Nighttime
-
24-hTABLE A-IT. Values o f L and L f o r
eq max P o s i t i o n A ( 1 5 - f t h e i g h t ) and P o s i t i o n B ( 1 5 - f t h e i g h t ) L ( 2 4 h ) = 71 dB A eq L (daytime) = 73 dB A (0600
-
2200 h ) eq Leq ( n i g h t t i m e ) = 66 dB A (2200-
0600 h ) Lmax (daytime) = 95 dB A Lmax ( n i g h t t i m e ) = 82 dB A TABLE A-111. V a r i a t i o n i n n o i s e l e v e l w i t h h e i g h t , dB Lcvcl d i f f e r e n c e r e Hcight r e f e r e n c e h e i g h t( a ) L e v e l r e c o r d , 4 : 3 0 - 5 : 0 0 p . m . , 2 7 M a y 1 9 7 5 ( b ) L e v e l r e c o r d , 7 : 3 0
-
8 : 0 0 p . m ., 2 7 M a y 1 9 7 5 ( c ) L e v e l r e c o r d , 2 : 3 0-
3 : 0 0 a . m ., 2 8 M a y 1 9 7 5 F I G U R E A - 1 S A M P L E R E C O R D S S H O W I N G T E M P O R A L V A R I A T I O N S I N N O I S E L E V E L A T P O S I T I O N A , 2 7-
2 8 M A Y 1 9 7 5( 2 7 M A Y ) ( 2 8 M A Y ) 8 0 I I I I 1 1 1 1 1 1 1 1 1 1 1 ~ ~ 1 1 1 1 ~ ~
-
-
-
-
-
-
-
-
-
7 5-
-
-
,
L q (DAY) = 72.9 -I L (24 HRS) = 71.3-
a
.-.
--
.
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. eq . ..-.-
m-
-0 F I G U R E A - 2 7 0 I 0- al A 6 5 6 0 V A R I A T I O N I N L FOR V A R I O U S I N T E R V A L S O V E R 2 4 H O U R S = q S O L I D A N D D A S H E D L I N E S ARE D E R I V E D F R O M S T A T I S T I C A L A N A L Y S E R D A T A . D O T T E D P O R T I O N I S D E R I V E D F R O M G R A P H I C L E V E L R E C O R D .-
Jx
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-
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-
L?
i
-
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L (NIGHT)=66.1-
-
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eqi,
-
-
-
-
...".
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-
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D A Y T I M E L N I G H T T I M E.
D A Y T I M E P l 1 1 1 l l 1 I I I I I I I I I I I I I I 1 5 1 8 2 1 2 4 0 3 0 6 0 9 1 2 1 5APPENDIX B
INSERTION LOSS OF VARIOUS BARRIERS
I n s e r t i o n l o s s e s f o r v a r i o u s b a r r i e r s a r e c a l c u l a t e d f o r
p o s i t i o n s B, C , D and f o r o b s e r v e r h e i g h t s o f 5 , 15 and 23 f t , correspon- ding t o g r o u n d - f l o o r , s e c o n d - f l o o r and t h i r d - f l o o r windows.
C a l c u l a t i o n s f o r r a i l w a y n o i s e a r e based on t h e assumption t h a t t h e main s o u r c e i s n e a r t h e ground. T h i s i s a p p r o p r i a t e most o f t h e time, although locomotive engine n o i s e would o r i g i n a t e a few f e e t above t h e ground.
Three b a r r i e r h e i g h t s a r e c o n s i d e r e d : 12, 16 and 20 f t . For a f e n c e - l i n e b a r r i e r t h e s t r u c t u r a l s t a b i l i t y o f t h e 16- and 2 0 - f t h e i g h t s may b e q u e s t i o n a b l e , b u t t h e a c o u s t i c a l consequences a r e i n c l u d e d h e r e
f o r comparison w i t h t h e b u i l d i n g l i n k b a r r i e r s . For a given b a r r i e r h e i g h t t h e f e n c e - l i n e b a r r i e r i s s l i g h t l y s u p e r i o r t o t h e b u i l d i n g - l i n k b a r r i e r f o r t h e h i g h e r o b s e r v a t i o n p o i n t s , and s l i g h t l y i n f e r i o r f o r t h e
g r o u n d - f l o o r p o s i t i o n s . Otherwise t h e two b a r r i e r s a r e s i m i l a r . The g e o m e t r i c a l d e t a i l s f o r t h e two b a r r i e r p o s i t i o n s a r e shown i n F i g s . B - 1 and B-2, r e s p e c t i v e l y . C a l c u l a t e d i n s e r t i o n l o s s e s f o r t h e two p o s i t i o n s and f o r r a i l w a y and highway n o i s e a r e given i n Table B-I.
TABLE B-I. I n s e r t i o n l o s s o f v a r i o u s b a r r i e r s r e l a t i v e t o highway n o i s e dB
B a r r i e r
Highway Noise
(a) Fence Line: 1 2 - f t
(b) Building Link: 1 2 - f t
Railway Noise
(a) Fence Line: 1 2 - f t 1 6 - f t 2 0 - f t (b) Building Link: 1 2 - f t 1 6 - f t 2 0 - f t Observation Point I I I 1
L I S T E N I N G P O I N T S B T 2 0 ' * 2 3 ' - .- -. . t 1 6 '
