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CONDITIONS, TRENDS & ISSUES Environmental Quality: Noise


Summary An environment relatively free from the intrusion of noise pollution is a basic right of all citizens. Unfortunately, an industrialized/urbanized society utilizes equipment that generates objectionable noise either from explosive combustion of fuels for propulsion or from mechanical linkage of equipment components. Engineering design can minimize noise to some extent, but often not to acceptable levels, particularly if large numbers of individual sources combine to create a cumulative impact. A Noise Element is one of the seven required General Plan elements in California. The purpose of the Noise Element is to establish standards that characterize an acceptable noise environment, and to develop an implementation program through which maximum attainment of acceptable noise levels can be achieved. This section of the Conditions, Trends and Issues Report reviews the 1977 Master Plan noise standards against existing noise levels in order to help establish an updated set of standards and an appropriate implementation program. The first section, definition of terms, provides an explanation of the technical terms and concepts used to measure noise levels; the second section, the impact of noise, describes the physical, psychological and economic impact of noise on the community. The following section, Berkeley's noise environment, reviews noise conditions and standards as described in the 1977 Master Plan and the Berkeley noise ordinance and compares these to existing noise conditions. Finally, in the issues for discussion section, noise issues and implementation alternatives are discussed.


Definition of Terms


In order to understand noise, one must first have a clear understanding of the nature ofsound. Sound is defined as pressure variations in air or water which can be perceived by human hearing. Sound moves through the air somewhat like waves in the ocean. The waves are alternate rings of compressed and then rarefied air moving away from a central source at a constant speed. As each wave--first a compression, then a rarefaction- -encounters an object, it exerts a force--a push, then a pull--on the object. This is why sound can break a glass or cause a window screen to vibrate. Noise may be defined as sound which is objectionable and disturbing to some individual. The objectionable nature of sound could be caused by its pitch or its loudness. Pitch is the height or depth of a tone or sound, depending on the relative rapidity of the vibrations by which it is produced. Higher pitched sounds are usually more annoying to humans than sounds with a lower frequency. Loudness is the intensity of sound waves combined with the reception characteristics of the ear. Intensity may be compared with the height of an ocean wave in that it is a measure of the amplitude of the sound wave. In addition to the concepts of pitch and loudness, there are several noise measurement scales which are used to describe the noise in a particular location. A decibel (dB) is a unit of measurement which indicates the relative intensity of a sound. The zero on the decibel scale is based on the lowest sound level that the healthy, unimpaired human ear can detect. Sound levels in decibels are calculated on a logarithmic basis. An increase of 10 decibels represents a ten-fold increase in acoustic energy, while 20 decibels is 100 times more intense (10 X 10), 30 decibels is 1,000 times more intense (10 X 10 X 10), etc. Therefore, one hundred decibels is 10 billion times as intense as one decibel. The human ear also responds logarithmically. Each 10-decibel increase in sound level is perceived as approximately a doubling of loudness. Human ears also do not respond equally to sounds of all frequencies. Very low frequencies or ultra-high frequencies are not detectable by humans. Sensitivity to sound peaks at the frequencies of typical human conversation, and drops off in either direction higher or lower. There are several methods of characterizing sound. The most common in California are the A weighted sound level or dBA. This scale gives greater weight to the frequencies of sound to which the human ear is most sensitive. Representative outdoor and indoor noise levels in units of dBA are shown in Table IV-E-1. Because sound levels can vary markedly in intensity over a short period of time, some method for describing either the average character of the sound or the statistical behavior of the variations must be utilized. Most commonly, one describes ambient sounds in terms of an average level that has the same acoustical energy as the summation of all the time-varying events. This energy-equivalent sound/noise descriptor is called LEQ. The most common averaging period is hourly, but LEQ can describe any series of noise events of arbitrary duration. Since the sensitivity to noise increases during the evening and at night--because excessive noise interferes with the ability to sleep--a 24-hour descriptor has been developed that incorporates an artificial noise penalty added to quiet-time noise events. The Community Noise Equivalent Level, CNEL, is a measure of the cumulative noise exposure in a community, with a 5 dB penalty added to evening (7 - 10 p.m.) and a 10 dB addition to nocturnal (10 p.m. - 7 a.m.) noise levels. The Day-Night Average Sound Level, Ldn, is essentially the same as CNEL, with the exception that the evening time period is dropped and all occurrences during this 3-hour period are grouped into the day-time period.


The Impact Of Noise


Sound is of great value to humankind. It warns us of danger and appropriately arousesand activates us. Sound gives us the advantage of speech and language which can calm, excite, or elicit joy or sorrow. But not all sound is desirable. Sounds that are valuable in one location may travel to places where they may not only serve no desirable purpose, but may interfere with and disrupt useful activities. Other sounds are noise only at certain times, in certain places, or to certain people. Obviously, there is a value judgment involved among people about what sound is unwanted. There is, therefore, no clear definition of "good" or "bad" noise levels in any attempt to generalize the potential effects of noise on people.

Ear Damage Exposure to intense noise can produce detrimental changes in the inner ear and seriously decrease the ability to hear. Some decreases are temporary, lasting for a few minutes or days after the termination of the noise, while others may be permanent or chronic whenever the noise exposure occurs. Ear damage is not normally associated with community noise exposure because the levels that are needed to actually damage the auditory receptors of the inner ear are well above those experienced at any reasonable separation between the source and the receiver. Mufflers are required on mobile equipment by the vehicle code, and stationary sources must be muffled to meet the requirements of the City Noise Ordinance. Levels that can actually cause ear damage simply do not occur in a community noise exposure setting.

Hearing Loss While physical damage to the ear from an intense noise impulse is rare, a degradation of auditory acuity can occur even within a community noise environment. Hearing loss occurs mainly due to chronic exposure to excessive noise, but may be due to a single event such as an explosion. Natural hearing loss associated with aging may also be accelerated from chronic exposure to loud noise. The Occupational Safety and Health Administration (OSHA) has a noise exposure standard which is set at just below the noise threshold where hearing loss may occur from long-term exposure. The safe maximum level is 90 dB averaged over 8 hours. If the noise is above 90 dB, the safe exposure dose is correspondingly shorter. Safe doses as a function of exposure level are as follows: As previously shown in Table IV-E-1, the noise level at a rock concert is 110+dB. A safe daily dose at 110 dB is 0.08 hours (5 minutes). Frequent attendance at rock concerts, or playing in a rock band, is a ready invitation to partial deafness. Maximum public exposure to loud community noise sources, such as the I-880 Freeway, is in the low 80 dB range. While such a level is highly intrusive into anyone's activities, it is not sufficient to result in hearing loss. The damage created by excessive community noise is therefore more psychological than physical. Psychological impacts may have subsequent physical manifestations, particularly from stress-related disorders, but such reactions occur outside the auditory tract. Many of the psychological and sociological effects of noise, such as sleep disturbance, stress and general annoyance, can be traced to the role of hearing in humankind's evolutionary development.

Sleep Disturbance Noise can interfere with sleep by either awakening a person or causing a shift from a deep sleep level to a shallower level. Brief sounds of sufficient intensity and fluctuating noise levels above 35-45 decibels have been shown to alter sleep patterns. Research indicates that when people are exposed to a great deal of noise they will complain of sleep loss and suffer a reduction of their feeling of well being. The potential for sleep disturbance (full wakening or a shift in the type of sleep) varies by time of night. It takes a much higher noise threshold to disturb a person in deep sleep early in the sleep cycle than it does closer to morning. Noise sensitivity also varies among individuals, with women being somewhat more noise sensitive than men with regard to sleep disturbance. Some selective "tuning" of noise sensitivity may also occur where there is subconscious processing of the noise signal. A person living near an airport may waken from a dripping faucet or a child's cough in another room but sleep through 747s passing overhead. In addition to sleep cycle interference, noise contributes to an inability to fall asleep. This delay of sleep onset shortens the hours of available sleep for persons having to rise at a fixed time. Whether sleep disturbance constitutes a health hazard is debatable. While good sleep is necessary for physical and mental health, normal persons who lose sleep compensate by spending more time in deep sleep, and by napping. It may be very difficult to deprive a normal person of sufficient sleep to produce adverse health effects. While there is limited physiological effect from sleep disturbance, adverse psychological reaction to sleep deprivation is common. Irritability from lack of sleep leads to interpersonal conflicts, reduces job performance, increases judgment reaction time and decreases attentiveness while driving a car. Excessively noisy environments are often populated by lower-income individuals with different group ethics than higher-income individuals who have moved to a quieter environment, making it impossible to distinguish behavior that may be resulting from disturbed sleep patterns from numerous other income and environment-related factors. However, in a laboratory setting where variables are better controlled, adverse psychological reactions to lack of sleep have been clearly documented. Interior residential standards for multi-family dwellings are set by the State of California at 45 dB CNEL. The standard is designed for sleep protection and most jurisdictions apply the same criterion for all residential uses. Typical structural attenuation is 10-15 dB with open windows. With closed windows in good condition, the noise attenuation factor is around 20 dB for an older structure and perhaps 25 dB for a newer dwelling. Sleep disturbance is therefore likely when exterior noise levels are 55- 60 dB CNEL with open windows and 65-70 dB CNEL if the windows are closed. Levels of 55-60 dB are common along collector streets and secondary arterials, while 65-70 dB is a typical value for a primary/major arterial. Levels of 75-80 dB are normal noise levels at the first row of development outside a freeway right-of-way. In order to achieve an acceptable interior noise environment, bedrooms facing secondary roadways need to be able to have their windows closed, those facing major roadways typically need a greater thickness of glass than a standard 1/8-inch pane, and those facing freeways need to be dual-glazed and not operable in order to achieve a sleep disturbance-free interior level.

Stress Physical stress reactions can be observed when people are exposed to noise levels of 85 dB or more. Dilated pupils, elevated blood pressure and increased stomach acid leading to a nauseous feeling are typical reactions when the noise environment is increased above those levels normally found in a community noise environment. While 85 dB is within OSHA's acceptable occupational exposure, chronic exposure to such levels by employees without hearing protection may lead to increased gastro-intestinal problems, even if the noise level marginally meets workplace standards. As with sleep disturbance impacts, adverse stress-type reaction to excessive noise is a two step process. Noise above 65 dB makes it difficult to have a normal conversation without raising one's voice. The constant intrusion of outside noise makes people irritable. Irritability creates interpersonal conflict. Conflict puts a strain on personal relationships that may then produce stress-related behavior among people affected by the noise. Not only is there a measurable effect of the noise (e.g., inability to clearly hear conversations, the television, music or to concentrate on reading or other work), but there is also an impact due to community perception. Exposure to excessive noise is perceived to be a price of lack of material success. People feel trapped if they can not open their windows without hearing truck noise rumbling through their house. Their quality of life is perceived by themselves (and others) to be degraded because they can not escape the ubiquitous noise. People on the "wrong side of the tracks" are mainly those who have to put up with such noise because those that can move to a quieter environment likely will have done so. The link between noise and socio-economic conditions may further lead to undesirable stress-related behavior or physical response among many people who are exposed to chronically excessive noise.

Economic Impact of Noise Since, all other things being equal, it is more desirable to live in a house that is quieter than in a noisy one, there must be an economic penalty associated with noise exposure. Noise alone, however, is not the only factor that may influence this decision. People living along a heavily traveled arterial may have greater problems with traffic safety, crime, air pollution, exhaust odor, dust deposition on their cars or furniture, excessive levels of lighting, or loss of privacy. All of these factors combined tend to depress property values. Pride of ownership may also not be as high along a busy street, such that homes may not be as well maintained, which may further depress property values. Commercial uses may be mixed in with residential use and may further reduce the desirability of living along a busy street. When all of these factors are considered, there is no way to isolate any economic impact that is directly attributable to noise alone. As noted above, the economic penalty of an undesirable noise environment may be linked more to the perception that noise degrades property and the quality of life than to an actual decline in property values. Noise tends to annoy people most after they have been exposed for some length of time. New purchasers or renters may be less aware of how intrusive the noise can be, so that the undesirability of living in a noisy environment may grow with time. Property values may therefore not necessarily be markedly affected by noise levels, especially considering all of the other variables, even though there may be a significant future negative reaction to the noise levels encountered.


Berkeley's Noise Environment


1977 Master Plan Several of the 1977 Master Plan policies found in the Noise Element are still relevant today, including the following:

  • Establish noise/land use compatibility standards (Policy 6.00);

  • Include these standards in land use decision making (Policy 6.00).

  • Encourage construction of noise walls along I-80 (Policy 6.02).

  • Enforce vehicle code noise limits (Policy 6.05).

Noise Ordinance The City's Noise Ordinance, last amended in 1982, was adopted in accordance with the 1977 Master Plan. The Noise Ordinance sets limits for permissible noise levels during the day and night according to the zoning of the area. Residential zones have quieter standards than industrial or commercial zones. One problem is that the Noise Ordinance does not recognize residents living in non-residential zones, such as in West Berkeley. In addition, if ambient noise (the general level of noise in the area) exceeds the standard, that ambient noise level becomes the allowable noise level. These provisions of the Noise Ordinance mean that there may be several areas--especially in West Berkeley--that are not noise compatible with existing residential uses. The Noise Ordinance is widely viewed as being both inadequate and hard to enforce. Consequently, the City Health Department is in the process of documenting the current state of Berkeley noise problems as a prelude to revising the Noise Ordinance. Enforcement of the Berkeley Noise Ordinance (Chapter 13.40 of the Municipal Code) is often related to commercial or industrial mechanical equipment that is sited nearby residential uses. The source of complaint is often as much from the duration of the noise (24 hours per day) as from the loudness itself. The equipment may be in compliance with all exterior noise standards as stated in the Ordinance and still the source is perceived to be a nuisance. The Ordinance does allow for abatement of a noise nuisance as defined as "loud, unnecessary or unusual noiseÉwhich causes any discomfort or annoyance to any reasonable person of normal sensitiveness." However, the subjective interpretation of this section is always a possible point of contention between the public and City staff charged with Ordinance enforcement. Ideally, a piece of equipment that is the source of conflict will be baffled, relocated or modified to solve the problem. Because noise conflict potential increases in areas where mixed uses are located in close proximity, such as West Berkeley, consideration of equipment siting is an appropriate part of any environmental review. Conflict resolution between industrial, commercial and residential uses is obviously also a relevant goal of the Noise Element.

Noise Sources Typical major noise sources in a community include: 1) aircraft near an airport; 2) trains near railroad tracks; 3) industrial plant equipment noise; 4) routine activities of daily life; and 5) cars, trucks and buses. The most important difference between transportation and non-transportation noise sources is that a municipality generally can exercise control on the level and duration of noise at the property line of any non- transportation source of noise. A city can only adopt noise exposure standards for noise levels resulting from trucks, trains or planes and then not permit land uses to be developed in areas with excessive noise for an intended use. Actual noise level generation from mobile sources is pre-empted by other agencies. However, a city does play some role in enforcing the requirement in the state vehicle code regarding properly operating mufflers and may set speed limits or weight restrictions on many streets that affect noise generation. In general terms, however, a city's actions are primarily pro- active with respect to non-transportation sources versus reactive for those sources beyond city control.

Bus Noise: While Berkeley has only a moderate number of trucks on its major streets, as sources of vehicular noise, there are a number of bus routes that have frequent service. Bus service is provided on all levels of the Berkeley circulation system including: major streets, collectors and locals. AC Transit restructured its routes about four years ago in order to put bus service within 1/4 mile of every resident and consequently, the noise environment on several of the new routes degraded. For purposes of assessing vehicular noise, three generic weight classifications are considered, i.e., less than 10,000 pounds, from 10,000 to 26,000 pounds, and vehicles over 26,000 pounds with three or more axles. Buses do not fit exactly into either the medium truck or the heavy truck category, and their measured noise emission characteristics are equally intermediate. At 35 mph, one medium duty truck is as loud as ten cars. One heavy truck is as loud as 30 cars. A bus is probably equivalent to 20 cars. In addition, bus noise may be worsened by grade or by pavement condition. Whether additions or changes in bus service have a detrimental noise impact depends somewhat on the baseline noise level that exists without the buses. Measurements have shown that background noise levels on "quieter" major streets in Berkeley are near 60 dB while the "noisier" streets are near 65 dB at the nearest residences. An increase of 3 dB is generally considered the threshold level at which people complain that their noise quality has become noticeably degraded. Assuming that buses are equivalent to heavy duty trucks in terms of noise generation (a conservative over-assumption), the following increases in noise level would be perceived at the nearest homes as a function of buses per hour: For a street with a low baseline noise level, the addition of six buses each way in one hour, equivalent of one bus every 10 minutes in each direction, would noticeably impact adjacent residents. For noisier streets, even ten buses each direction (one every 6 minutes) does not significantly worsen the noise level. Given that most major streets in Berkeley have baselines above 60 dB, the bus noise generation estimate is over- predictive, and that few routes run more than six buses each direction per hour except on already heavily traveled roadways, Berkeley bus routes are not a major source of impact with respect to average noise perception thresholds. However, people do not typically hear average noise--they hear peaks. They hear bus brakes, shifting gears and acceleration from the bus stop. Thus, while measured noise impacts are within acceptable levels, it is the nuisance element of bus operations that causes problems for some people. Another aspect of human nature is that once a certain type of noise is perceived to be offensive, conscious awareness of repetition of that nuisance is much higher. Thus, while it is difficult to ascribe an adverse impact to bus noise based on numbers alone, some residents, particularly older people who can remember a quieter time, may nevertheless feel significantly intruded upon by existing bus routes in the City. In the 1977 Master Plan the City adopted a policy of bus service within 1Ú4 mile of each resident. AC transit cooperated and implemented route changes to fulfill that policy. Noise issues in this General Plan process will need to be judged in the context of such goals. Reduction in bus service to eliminate noise would lead to increased automobile noise and to an increase in other environmental impacts like air pollution.

Other non-Stationary Sources: There are no airports in Berkeley and thus aircraft noise is not typically a problem in the City. The railroad tracks create a linear noise corridor that is shielded to the east by a considerable number of substantial structures that reduce the noise envelope from trains. Most of the BART trackage is below grade which again limits the noise impact potential. Transportation noise in Berkeley is dominated by the automobile and by noisy trucks.

Stationary Noise Sources: Noise sources related to heavy manufacturing and located mainly in industrialized West Berkeley, were once a more dominant contributor to the noise environment. In the past, noise-related land use conflicts were at a minimum between West Berkeley and other sectors of the City, given the buffer distance. However, in those areas zoned for manufacturing a wide range of uses are permitted, including residential. The presumption has been, as in most traditionally zoned industrial areas, that noise generated through an industrial use was an acceptable part of the manufacturing process. More recently, however, increased residential and commercial uses in West Berkeley have begun to threaten industrial uses, in part, through a changing perception of environmental standards as they relate to the manufacturing process. The Concept Plan for West Berkeley, was adopted in 1991 to address these type of conflicts in order to maintain the historic mix of land uses in an environmentally responsible manner. The Draft West Berkeley Plan, currently under review, calls for more stringent environmental review and regulation, including the mitigation of noise both through industrial and residential measures. Routine activities that generate noise and may create conflict include a wide variety of sources. Barking dogs, loud music, horns and sirens, shouting children, construction equipment, burglar alarms, etc. are all potential noise irritants. The City Noise Ordinance has a number of prohibitions in addition to a general prohibition against creating a nuisance or disturbing the peace. In many cases the impacts are highly localized. Activities at one location often affect only a few noise-sensitive receivers nearby. A barking dog, a teenager's stereo or somebody operating a power tool at night may affect only one or two neighbors. Enforcement of the Ordinance occurs primarily in response to a complaint to the police or to a code enforcement officer. Making a complaint may pit one neighbor against another, so that there may be a natural reluctance in many instances to cause trouble for a neighbor. As housing has become denser in Berkeley, the distance benefit that formerly reduced conflict has diminished. This reduction in sense of community makes some people less careful if they annoy their neighbors through loud music or late-night activities. It may perhaps be only a perception by an older generation that some younger people are less considerate in respecting the privacy of others, including auditory privacy. It is, however, a widely held perception whether it is justified or not.

Noise Abatement There are three basic mechanisms for reducing excessive noise exposure. One is to reduce the strength of the noise at the source, another is to increase the distance between the source and the receiver, and the third is to place an obstruction between the noise source and the receiver. Given that vehicular noise is exempt from local control and relocation of sensitive land uses away from freeways or major streets is not practical, a noise wall is often the remaining practical solution. Noise walls have their positive and negative aspects. They reduce the noise exposure to affected residents, students or other sensitive uses if they can effectively block the line of sight between source and receiver. A properly sited wall can reduce noise levels by almost 10 dB. A decrease of 10 dB is perceived by people to be about one-half as loud as before. Unfortunately, the social, economic and aesthetic costs of noise walls are high. Proposed noise walls along I-80, for example, would screen the traffic from West Berkeley receivers, but also the view of the water from Aquatic Park. Graffiti is a notorious maintenance problem, as is the feeling to drivers that they are stuck in a tunnel or a prison surrounded by massive walls. Construction costs of noise walls is $100-200 per foot. Each mile of wall thus costs from 0.5 to one million dollars. Finally, a freeway that is one-half as loud as before is still very loud. Many people express great disappointment after completion of a sound wall because the noise problem only diminished slightly, and did not disappear as had been their expectation. Caltrans has several noise abatement programs in place which focus on walls or berms as the mechanism to reduce noise intrusion from State and/or Federal highways. If new through lanes are added to such roadways, and there are existing park or residential uses that currently or in the future will exceed the Federal noise abatement criterion (called NAC - a 67 dB exterior for any one hour), a noise impact mitigation feasibility study is required, and barriers must be made part of the project where feasible and desirable. On the other hand, sound walls constructed as part of retroactive noise remediation must compete with all other wall needs throughout the State and needs far outstrip current funding. Because of the competing impact of sound wall costs versus benefits, Caltrans is sensitive to the wishes of the affected community regarding wall construction. Caltrans will generally support design features that minimize local objections as long as their own design standards are met. Those standards include the following:

  • Walls must reduce noise levels by a minimum of 5 dB.

  • Walls must be able to block truck exhaust stacks that are located at 11.5 feet abovethe pavement.

  • Walls within 15 feet of the outside of the nearest travel lane must be built uponsafety-shaped concrete barriers.

The preferred wall material is concrete or masonry. The effectiveness of a material instopping sound transmission is called the transmission loss (TL). Some TL values for materials that have been used for sound walls are as follows: Materials other than a heavy metal or concrete masonry unit are more typically used on a single unique project basis rather than along several miles of freeway.

Measurements Methodology: In order to obtain a current noise "snapshot" of Berkeley, approximately 20 representative locations throughout the City were monitored for current noise exposure. Measurement sites were chosen to provide a representative spectrum of the community's existing noise environment. The focus was on locations where there might be a reasonable expectation of quiet, such as parks, medical facilities, schools and residences. A few of the sites were selected because they were known to be noisy and thus provide some basis for comparison with some of the less noisy locations.

Measurements were made using two LDL Model 700 noise monitors during a two-day period on March 4-5, 1993. Each site was monitored for approximately 30 minutes. Although noise/land use compatibility standards are typically expressed as CNEL or Ldn, monitoring experience in traffic-dominated environments has shown short-term, mid-day LEQ and weighted 24-hour CNEL to be quite similar. Along commuter routes where there is heavy pre-7 a.m. traffic, the nocturnal penalty assigned to noise events before 7 a.m. in the CNEL or Ldn descriptor creates 24-hour weighted readings that tend to be 2-3 dB higher than average daytime levels.

Results: Results of the community noise monitoring are summarized in Table IV-E-2. Monitoring locations are shown in Figure IV-E-1 keyed to the site numbers in Table IV- E-2. The quietest locations were parks or schools on low traffic streets or places where traffic was screened by topography or distance.

The noisiest locations were along Ashby Avenue, combined street and traffic activity along Telegraph Avenue, and a high activity center on the U campus. Noise levels along a number of secondary arterials on the front porches of homes along these streets were in the mid-60 dB range. Traffic noise begins to intrude into normal conversation at a noise level of approximately 65 dB. Assuming that the mid-day, short-term readings in the mid-60 dB range are close to the weighted 24-hour noise exposure, the noise level at a considerable number of residences in Berkeley marginally meets or slightly exceeds established standards for noise- sensitive land uses.

With normal structural attenuation of 10-15 dB with open windows, interior noise levels along most Berkeley roadways of 50-55-dB are well above the recommended 45 dB interior level. Interference with activities requiring quiet, such as sleeping, reading, etc. can be expected at any residence, rest home, classroom or similar quiet-oriented use facing any roadway with moderate traffic volumes in Berkeley. Those locations away from traffic influence were well within normally acceptable levels, reflecting a considerable homogeneity of noise exposure across the city. Forty-two sites were monitored around the City in 1975 during development of the Noise Element for the 1977 Master Plan. These sites were heavily street noise-oriented and many readings were taken at corners where traffic noise from two roadways was combined. Because the emphasis of the current measurements was to focus on the receiver and less on the source, the two data sets cannot readily be compared.

The average reading of 68 dB in 1975 was higher than the 62 dB average of the 1993 measurements. However, since the 1975 data was not very specific in terms of location and roadway setback, the previous work cannot be readily duplicated to determine the degree of change since 1975. Since most people can not detect ambient noise differences of less than 3 dB, and it takes a doubling of traffic volumes to increase noise levels by 3 dB, very few Berkeley receiver sites have likely experienced a perceptible change in noise levels since 1975. Long-time residents probably sincerely feel that noise levels have become significantly degraded within the last two decades. However, it was noisy in 1975 and it is slightly noisier in 1993. Some locations such as the West Berkeley industrial sites that had Ldns in the low 80's in 1975 are probably less noisy now. Those roadways that have maintained a reasonable travel speed despite moderate volume increases are probably slightly noisier. Clearly, traffic noise is a pervasive problem in an urbanized environment that will not change much in Berkeley until some quieter mode of transportation replaces the combustion engine vehicle in use throughout most of the last century. Because a brief noise measurement is only representative of one instant in time at one location, the process of calculating community traffic noise exposure is generally performed using a computerized noise model based on average conditions (volumes, speeds, truck mixes, etc.), rather than on those monitored at one fixed point in time.

Traffic noise exposure was calculated along a number of Berkeley area roadways at a distance designed to duplicate the approximate nearest sensitive receiver location relative to the roadway centerline. The results of the model analysis are shown in Table IV-E-3. Of the 29 streets analyzed, only 3 had noise levels at the nearest receiver location that did not exceed the 65 dB CNEL goal for noise-sensitive land uses. Six roadways had noise levels of 70 dB CNEL or more at the face of the nearest noise-sensitive structure. University and Ashby Avenues are the noisiest streets in the city. Small decreases in noise levels have occurred along much of San Pablo Avenue and along portions of Ashby Avenue. Noticeable noise increases (3 dB or more) have been observed along a considerable number of roadways, including portions of Sixth Street, Martin Luther King Jr. Way, Milvia Street, Shattuck Avenue, Oxford Street, Claremont Avenue, Grizzly Peak Boulevard, Gilman Street, Hopkins Street, Delaware Street, Hearst Avenue, and Dwight Street.

Changes Since 1977 The Noise Element of the 1977 Master Plan, first prepared in 1975, concluded that the existing City noise environment was dominated by traffic noise. This is the same conclusion in 1993. Since 1975, several factors have changed somewhat, but not enough to substantially change the overall role of traffic's noise domination. Factors that have reduced noise since 1975 include the following:

  • Overall traffic speeds are less. Slower traffic is often less noisy than free-flowmovement.

  • Truck noise standards from the 1970-80's have created a quieter truck fleet.

  • Truck volumes on many streets in the West Berkeley area are lower, as heavymanufacturing has decreased or has been converted to uses that involve quieter medium-duty vehicles rather than diesel-fueled 18-wheelers hauling heavy loads.

  • A noticeable increase in the number of alternative means of transportation besidesthe single occupant automobile.

  • Reduction in employee commuting in former job-rich areas, such as West Berkeley,in response to decreases in industrial activity has reduced volumes on some area streets despite overall average city-wide traffic growth.

Factors that have increased noise since 1975 include the following:

  • Traffic volumes on many streets have increased.

  • Much more traffic occurs before 7 a.m. than two decades ago. According to thecommunity noise metrics of CNEL or Ldn, any car traveling before 7 a.m. counts as ten cars in the noise equation.

  • Pass-through traffic seeking alternatives to crowded freeways often use City streets.

  • Closure of residential side streets formerly used as alternative routes has funneledmore traffic onto already noisy arterials.

  • There has been a marked increase in the use of noisy motorcycles and scooters by Ustudents because parking and traffic near campus make use of a car impractical.

Locations of ConcernThe noise monitoring and modeling conducted for this study reveal the following areas of particular concern:

  • Noise levels along many roadways north of University Avenue are excessive forolder residences with minimum setbacks and inadequate noise insulation.

  • Noise levels along University and Ashby Avenues in homes, schools, libraries andother noise-sensitive uses are at unacceptable levels.

  • Noise levels along historically quieter streets, such as Grizzly Peak Boulevard arebeginning to reach undesirable levels.

  • Residential conversion (whether by demolition/construction or live/worksituations) in West Berkeley may create more residences within freeway and train noise impact zones.


Issues For Discussion


The noise conflicts resulting from the existing patterns of land use and transportationwithin the City of Berkeley cannot be expected to substantially diminish of their own accord, particularly in a time of limited resources. Beyond a complete re-evaluation of these basic land use and transportation patterns, implementation actions to ameliorate these conflicts must be considered. Further constraints are posed by the limited jurisdiction that City's have in controlling the major noise generators of trucks, automobiles, and motorcycles. An additional concern in Berkeley is the inadequacy of the Noise Ordinance in protecting noise-sensitive uses in areas with high ambient noise levels.

Specific questions to be resolved include the following:

  • What noise standards (interior/exterior) should be most appropriately applied to theland use decision-making processes?

  • Can the Noise Element include the adoption of effective noise level/land usecompatibility criteria?

  • How can the existing Noise Ordinance best be modified to further protect residentialand other noise-sensitive uses in high ambient noise level areas, such as West Berkeley?

  • What actions can be initiated by City government and Berkeley citizens to maximizenoise reduction within the context of limited resources and limited expectations of dramatic land use and transportation changes?

  • What noise abatement technology can be most effectively applied to reduce existingexcessive noise exposure?

  • How can the University and other higher education institutions in Berkeley help toencourage less noisy behavior by students living in close proximity to noise-sensitive uses?

  • Can the level of enforcement for permitted noise levels be increased for motorcycleand scooter traffic?

  • Are there engineering or right-of-way improvement solutions that can beimplemented to reduce noise levels along Ashby and University Avenues?

  • How can the updated Noise Element and revised Noise Ordinance best worktogether to improve the noise environment of Berkeley?


Conclusions


Although traffic noise changes in Berkeley have not been uniform in the last twodecades, the factors that serve to increase traffic noise are slightly more dominant now and most areas of the City are somewhat noisier now than in 1975. The 1977 Noise Element concluded that: "most of Berkeley is impacted by noise." This basic conclusion remains applicable today. However, with the concurrent revision of the Noise Ordinance and update of the Noise Element, the City does now have an opportunity to set forth clearer land use/noise compatibility criteria, and mitigation and enforcement mechanisms to improve the noise environment of the City.

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