College Avenue Safeway rebuild

Invitation for Rockridge Soundwall Meeting:

Final project link with text

Final City of Oakland Caldecott Settlement Project List:

Final project link with text

Oakland's final project list with linked project fact sheets


SR-24 Noise Barrier Scope
Summary Reports fact sheet

Additional Materials

Noise Study Executive Summary

Hwy. 24 Noise Study

Want to know about soundwalls?

Sound Facts About Soundwalls Series

News in reverse chronological order

October 6, 2012: City Discusses Study Process, Soundwall Technology With Residents

More than 80 Rockridge residents crowded into the Rockridge Library meeting room on September 27 to hear about soundwalls and the process that might lead to their construction in the Rockridge area.

Organized by the city of Oakland, the meeting presented a wealth of technical information on sound wall functionality, the sound wall study process, landscaping considerations and the preliminary technical report evaluating noise levels in Rockridge.

Following overviews by Zac Wald, chief of staff for Councilmember Jane Brunner, and Victoria Eisen, consultant to the city for the settlement project process, Wlad Wlassowsky, head of Oakland's transportation services division, talked about funding and the projects. He explained that the decision facing the city and the neighborhood was not about building soundwalls, but whether to do the additional studies known as Noise Barrier Scope Survey Reports (NBSSR) needed prior to construction decisions.

Studies for two sections of SR 24 in Rockridge – eastbound from Vicente Way to Broadway and westbound between Ross Street and Telegraph Avenue – could proceed if supported by a two-thirds majority of affected property owners (generally the first two rows of residences along the freeway). This is the same level required for other transportation projects on residential blocks, such as permit parking and speed humps. Caltrans engineer Glenn Kinoshita said soundwalls could be most effective for residents whose line-of-sight to freeway traffic would be blocked by a soundwall 10-14 feet high. For other residents, a change in sound volume is possible, but likely not noticeable. Kinoshita said various soundwall designs are approved by Caltrans. More expensive than masonry walls, transparent soundwalls were justified on I-580 in San Leandro because their lighter weight did not require retrofitting the elevated superstructures. In Rockridge, there is too little space bordering the freeway to use trees or other vegetation as natural sound barriers.

Invited to comment or ask questions, two residents said the study money, drawn from the $8 million Caltrans settlement with the city, would be better spent on others. projects. Most other comments were either neutral or supportive of the study process. Several speakers urged consideration of more aesthetically pleasing transparent soundwalls such as found in Europe and Asia.

Before year's end, the city will identify relevant property owners and distribute official petitions. Soundwall studies may proceed if sufficient support is shown by the end of the petition period, probably next September.

September 6, 2012: Soundwalls in Rockridge? City Hosts Public Meeting on Caldecott Settlement Studies Sept. 27

The next chapter in the process of determining the future of soundwalls at three State Route (SR) 24 locations in Rockridge and Temescal will unfold starting at 7 p.m. Thursday, September 27, at the Rockridge Branch Library.

At this informational meeting, sponsored by the city of Oakland, city and Caltrans staff and their consultants will:
1. Provide a history of the Caldecott Tunnel Settlement Agreement funding and why soundwall studies are eligible
2. Explain the dynamics of freeway noise and how soundwalls work
3. Go over the visual aspect of soundwalls
4. Present the findings of a 2009 study of potential soundwall locations in the area, and
5. Discuss next steps in the process of gauging community sentiment for soundwalls at particular locations.

Fourth Bore Settlement Agreement
As readers of The Rockridge News may recall, in 2008 the city received an $8 million settlement from Caltrans over the environmental assessment of the fourth bore of the Caldecott Tunnel. According to the terms of the settlement, this funding was to be used for projects that "have as their primary purpose the improvement of pedestrian, bicycle, transit and local street improvements, noise barriers, including projects that support the use of transit (and the reduction of single-occupant motorized vehicles, such as transit signal coordination and amenities), to the greater community in the Highway 24 corridor between I-580 and the Caldecott Tunnel."

In 2010, the city initiated a community process to determine how to spend the settlement. Walking tours were held in the neighborhoods covered by the agreement: North Hills nearest the tunnel, Rockridge and Temescal. Based on a preliminary project list that was part of the settlement agreement and conversations on the walking tours, a new draft list was developed, and was presented and discussed at a public meeting last year. The city received over 250 comments on the projects on this list. This input informed the final project list, which includes "noise barrier" or soundwall studies at the following three locations:
■ Eastbound between Vicente Way and Broadway
■ Westbound between Ross Street and Telegraph Avenue
■ Westbound between Patton Street and Ross Street.
Although the settlement fund is not nearly sufficient to cover the cost of constructing even one of these soundwalls, the city would need to study further one or more of these projects in order to apply for state construction funding.

Soundwall Studies

In 2009, Caltrans commissioned a noise study of SR 24 between SR 13 and I-580 to determine the feasibility of soundwalls along the corridor. The study – known as a "pre- NBSSR" (Noise Barrier Scope Summary Report) – looked at nine potential locations along the Rockridge/Temescal corridor (five eastbound and four westbound). It measured current noise levels near the freeway, predicted the effectiveness of soundwalls at each location, and compared this data with Alameda County Transportation Commission (Alameda CTC) soundwall construction funding criteria. The study concluded that four of the nine locations would meet the criteria Alameda CTC uses to assess applications for state soundwall construction funding. These four segments include the first two in the bulleted list above (Eastbound between Vicente Way and Broadway, and Westbound between Ross Street and Telegraph Avenue), but not the third (Westbound between Patton Street and Ross Street), which the study concludes is "estimated to provide no benefit to affected residences."

Alameda CTC's criteria for funding the construction of soundwalls at a particular location are:
■ The existing or future predicted exterior noise level is 65 decibels (dB)
■ A reduction of at least 5 dB resulting from the installation of a soundwall can be achieved
■ The projected cost will not exceed $45,000 per dwelling unit affected by the soundwall (based on year 2002 costs)
■ The residences were developed prior to opening the freeway to traffic.

Now that the city knows which soundwall segments on the funding list satisfy Alameda CTC's criteria, if it chooses to pursue one or both of these projects, it will need to conduct a full NBSSR. NBSSRs differ from pre-NBSSRs in their depth and breadth. An NBSSR is a full Project Study Report, an engineering report that documents agreement on the scope, schedule, and estimated cost of a project so it can be considered for future state construction funding. Given the expense of an NBSSR, jurisdictions undertake them only when they have the intent to build the studied project(s).

More: September 27 Meeting

Beyond discussing in more detail the historic and technical issues raised in this article, Oakland staff will present a process for determining whether settlement funds should be spent for further study of the potential for soundwalls at various locations in Rockridge and Temescal and how that process compares to existing similar city procedures and those used by other public agencies.

Meeting participants will have the opportunity to ask questions of any of the presenters, and to comment on staff's proposed decision-making process.

For more information about the September 27 meeting or the Settlement Agreement process and projects, please contact the city of Oakland's Caldecott project consultant, Victoria Eisen, at 510/525-0220, or e-mail

July 6, 2012: Soundwalls: Process, Benefits and Drawbacks to be Topics of a September Community Meeting

above line soundwall map During 2010 and 2011, the city of Oakland developed a ranked list of projects funded with the $8 million Caltrans paid Oakland in a settlement reached over the adequacy of environmental reports which studied effects on the neighborhood of the Caldecott Tunnel's fourth bore construction.

The final list of 37 projects is available online at Twenty-one projects totaling $8 million are "above the line," meaning they receive first consideration for the money. The line was established during several community meetings when participants ranked suggested projects in terms of their importance to community safety and improvement.

Soundwall studies were placed on the city's list due to the higher freeway noise levels anticipated after the Fourth Bore is opened and to current noise levels measured in the December 2009 pre-NBSSR study. The three "above the line" Rockridge soundwall segments are indicated on the above graphic. Note their location in terms of schools, the park, and other public uses. All segments can be found here:

The next step in evaluating support in the neighborhood for soundwalls is through property owners' petitions for the NBSSR studies. Information on the petition process, the overall soundwall approval and construction process, and on properties of soundwalls will be presented at a public meeting scheduled Thursday, September 27, 7-9 p.m. at the Rockridge Library. Your participation is important to the process.


May 5, 2012: On the Nature and Likelihood of Soundwalls Coming to Rockridge

The possibility of the construction of soundwalls along Highway 24 through parts of the Rockridge-Temescal area has raised many questions. This fourth article on soundwalls (following up on those in the May, June and July 2011 issues of The Rockridge News) will consider the nuts-and bolts of soundwalls, some "urban legends" surrounding them, and the processes by which they are or are not constructed. San Leandro lightweight transparent soundwall

Sources of Freeway Noise

Freeway noise comes from many sources: tires on pavement, including noise as they hit bumps, potholes, and cracks; engine noise, which varies with the type of engine— cars make some noise, diesel trucks and motorcycles make much more. While the noise originates in the engine, most of it comes out from the exhaust pipe, reduced somewhat by the muffler; and the noise of air displaced by cars and trucks as they travel. Trucks create a distinctive and particular sound when the driver applies engine braking or Jake's Brakes, a compression release mechanism that releases a mechanical gargling sound.

All of this noise increases with the number of cars and their speed. However, as the number of vehicles nears the freeway's capacity, speed diminishes, as does noise. Thus, a traffic jam produces far less noise than free-flowing traffic. Weather also affects noise levels, with perhaps the biggest effect being increased noise from tires moving on wet pavement.

What Can Soundwalls Do?

A soundwall's basic act is to block or deflect freeway traffic sound. Sound travels as waves, but often behaves as if it were a series of little balls. When the soundwave balls hit a soundwall barrier, they bounce off the wall in an organized manner (reflection); they bounce off the wall in random directions (diffusion); or they stick to the wall (absorption). A small amount of sound will pass through the wall.

Because sound generally travels in straight lines, placement of a soundwall blocking the straight-line path between the noise source and the listener serves to deaden the noise. Conversely, if the lineof- sight isn't blocked, neither is the sound. Soundwalls usually don't help people living on the upper stories of buildings.

People often worry whether the sound reflected off lightweight soundwall ground viewa soundwall will increase noise on the opposite side of the freeway. The answer is: generally, no.

First, sound dissipates over distance. A truck's diesel exhaust noise, for example, drops by five decibels (dB) with each doubling of the distance from the truck. [A decibel is a unit of "loudness." A 10 dB noise difference will make a noise sound half as loud.] The truck noise that travels across the freeway, hits a soundwall and bounces back, will be five dB softer when it gets back to where it started.

The second factor is diffusion. If the soundwall has a rough surface (as do most, by design), a lot of the sound will bounce back in random directions, spreading out and dissipating its energy and noise level. Even when sound bounces back the way it came in, it is reflected back, like light hitting a mirror, at the same angle that it came in. Most freeway noise starts near the roadway surface. When it hits the sound wall, it's going up. When it bounces off the soundwall, it keeps going up. By the time it gets to the other side of the freeway, it's many feet above the freeway. That reflected sound generally dissipates harmlessly.

A Legacy of the Past

If Highway 24 were built today, soundwalls would most likely be installed. Federal and California regulations mandate sound protection when new freeways are constructed. However, Highway 24 was built before these regulations were in effect. Therefore, soundwalls, if built, would be a retrofit. That complicates matters. Not only was the roadway not designed to accommodate soundwalls, but the surrounding area comes very close to the freeway, leaving little room to put them up.

The Good, the Bad, the Ugly

A plus for soundwalls is the protection they can offer to people living next to the freeway. This is important in Rockridge where the homes and the freeway are old. Most Rockridge homes are not equipped with double-paned windows and newer insulating materials that could reduce noise in the home. It is possible that soundwalls could reduce freeway noise by 5 to 10 dB for homes near the freeway.

However, the esthetics of Caltrans' concrete block soundwalls are stark, at best. Happily, that type of soundwall is not likely to be built in Rockridge since Highway 24's elevated structures weren't built for the extra weight of heavy concrete walls. Caltrans has recently installed transparent soundwalls on some nearby overpasses, as shown in the accompanying photos. While somewhat less effective in blocking noise, they preserve views and a sense of the roadway's openness.

Building Soundwalls, or Not

The Alameda County Congestion Management Agency (ACCMA*) Freeway Soundwall Policy adopted in 2002 and later revised, defined a review and ranking system for retrofit soundwall projects. The policy defines four criteria for determining if a soundwall is warranted:
■ The existing or future predicted exterior noise level is 65 dB.
■ A reduction of at least 5 dB resulting from the installation of a soundwall can be achieved.
■ The projected cost will not exceed $45,000 per dwelling unit (based on year 2002 costs) affected by the soundwall.
■ The residences were developed prior to opening the freeway to traffic.

The process for implementing sound walls is twofold: 1. the initial screening process; and, 2. the Noise Barrier Scope Summary Report (NBSSR) process, a detailed noise study analysizing the four criteria above.

The screening process starts with a request for a soundwall. The jurisdiction, in this case the city of Oakland, agrees to sponsor the request and take responsibility for coordinating public input. As one element of the city's settlement agreement with Caltrans, an initial screening, or pre-NBSSR study, was conducted by Caltrans' consultant along Highway 24 between Highway 13 and I-580 to determine whether soundwalls were warranted. The pre-NBSSR study identified four areas along SR 24 that meet the criteria of the ACCMA soundwall policy and are considered cost-effective.The study, accepted by the ACCMA, is available at

The next step is evaluating support in the neighborhood for soundwalls through property owners' petitions. A petition favoring construction of a soundwall must be signed by a property owner from 100 percent of the households with a property line immediately facing the proposed soundwall and 75 percent of the households with a property line not immediately facing the proposed soundwall, but experiencing a minimum 5 dB in noise reduction (typically 200-300 feet from the roadway). If the required quotas of petition signatures aren't submitted, the city can appeal to the ACTC, if it feels public support is nonetheless strong.

If enough qualifying signatures are gathered and the city of Oakland supports moving forward, a Noise Barrier Scope Summary Report (NBSSR) process is initiated. It must include:
■ A detailed cost estimate.
■ Life cycle of the soundwall.
■ Consideration of the environmental impacts such as blocking residents' views or scenic vistas.
■ Engineering feasibility.

Upon completion of the report, the city of Oakland must hold a public meeting and adopt a City Council resolution in support of the proposed soundwall. The final step is funding the actual soundwall construction.

The Oakland Settlement Agreement provides Caltrans funding for Highway 24 NBSSRstudies, should they progress to this stage, significantly shortening the development process. Two soundwall sections, eastbound from Vicente Way to Broadway and westbound from Ross Street to Telegraph Avenue, would receive $554,000 and $628,000 respectively for the studies.

If the NBSSR studies will not be pursued, the agreement's $8 million funding line will be moved down to projects lower on the final list (see

An informational meeting on soundwalls and the process of having them studied, approved, funded and constructed will be held in the near future. Check the RCPC website at for more information or contact

* The ACCMA has since been replaced by the Alameda County Transportation Commission (ACTC). Same job, different name

July 2, 2011: Freeway Sound: Pervasive, Possibly Harmful If Unmanaged

Noise is one of the most pervasive pollutants in our environment, and, in Rockridge as in many communities, much of it originates from surface transportation: cars, trucks, trains, and motorcycles. This noise can be difficult or expensive to block in older homes, and nearly impossible to block in yards outside the homes.

Noise is unwanted sound and can be harmful at certain levels. The most obvious problems involve hearing loss from exposure to loud noise. The World Health Organization (WHO) recommends a limit of 70 dB (decibels) to avoid the risk of hearing loss with long-term exposure. But persistent noise pollution at lower levels can have less obvious health effects on our nervous systems, often causing a general decrease in a sense of well-being and interference with communication, relaxation, and recreation.

Levels as low as 30 dB can interfere with sleep, and can impair the ability to concentrate in classrooms. Research suggests that learning is affected starting at background sounds levels as low as 35 dB. Above about 50 dB, people express moderate annoyance in outdoor settings, such as when talking with a neighbor, playing with a child, or trying to enjoy a barbecue. At about 55 dB, people begin to express serious annoyance in outdoor living areas, and also moderate annoyance indoors or on school playgrounds.

The ambient levels of around 60-70 dB, regularly measured near Rockridge homes fronting the freeway, are significantly higher than any of these thresholds.

Until the late 1960s — after SR 24 (State Route 24, the freeway through Rockridge) was planned and mostly constructed— there was little awareness that people should be protected from the adverse effects of environmental sound. This changed in 1969 with passage of the National Environmental Policy act (NEPA); creation of the Environmental Protection Agency (EPA) in 1970; passage of the California Environmental Quality Act (CEQA) in 1970; passage of the Noise Control Act (NCA) of 1972; and publication of the WHO Guidelines for Community Noise released in 1980 (and most recently updated in 2000). These regulatory acts began to inform traffic noise regulations adopted by the Federal Highway Administration (FWHA), and now must generally be considered by agencies eligible for federal transportation funding, such as the California Department of Transportation (Caltrans) and the Alameda County Transit Commission (ACTC).

Given what we know about the present noise levels from SR 24, the freeway could not have been built in its current configuration, at least not without noise barriers or other mitigating measures.

Today, sections of SR 24 may be eligible for noise barriers if the sound level at nearby households reaches, or is predicted to reach, 65 dB or higher without a barrier, and a feasible sound wall is predicted to lower the noise level by at least 5 dB at a sufficient number of residences to make its construction cost effective.

June 4, 2011: On Soundwalls and Rockridge: Sound

Since the 1970s, the transportation system comprised of Highway 24 and BART that bisects Rockridge has been both a boon and a bane to the neighborhood: It's convenient for getting around but often a negative in terms of both air pollution and noise pollution. Could the latter problem be addressed with the construction of noise barriers, or soundwalls?As noted in the May issue of The Rockridge News, the settlement with CalTrans providing for mitigations of the construction effects of the 4th Bore of the Caldecott Tunnel includes funds to study the need for soundwalls at points along Highway 24. Soundwalls can be controversial for their esthetics, and often generate debate over their effectiveness and their potential to affect scenic views.decisions to place soundwalls along a roadway involve the wishes of people living near the road. RCPC and The Rockridge News present this and subsequent articles in the newsletter that will attempt to clarify the issues for those who may ultimately be affected by soundwall construction. Because of the topic's complexity, this month's article is presented in Q&A format.

Q: What is the difference between "sound" and "noise," and how are they measured? A: Sound is vibrations in the air, and, basically, noise is any unwanted sound, obviously a subjective distinction. Sound vibrations move in waves through air and other materials. Sound is measured in decibels (dB), a logarithmic unit. Here are the measures of some common sounds: Pin dropping, 15 dB; normal conversation, 60 dB; hairdryer, 80 dB; a car passing at 10 feet, 80 dB; front seat at a rock concert, 130 dB. Government health guidelines suggest ear damage can occur at as low as 85 dB.The decibel scale differs from the more familiar numerical scale used in weights and measures. For example, if a 100-pound person gains 10 pounds, his or her weight has gone up 10 per cent. By contrast, when a 100 dB sound increases to 110 dB, its intensity has gone up ten-fold. On the other hand, your ear will hear it as being twice as loud.

Q: How do we characterize sound? A: Sounds have direction, intensity (loudness), and frequency. Sound waves typically travel in many different direc-tions simultaneously, as does light from a light bulb. A sound's intensity is a measure of how much air pressure changes as the sound passes. Frequency measures how fast the variation in air pressure occurs, corresponding to what musicians call pitch.

Q: What sounds make up freeway noise, and how does it change with distance from the source? A: The hum of tires, the growl of engines and transmissions, the hiss of air moving past vehicles, and the vibration of the roadway make up the cacophony. Sound traveling in open air from a single car drops by about 6 dB, a noticeable difference, when the car doubles its distance from the listener. A decrease of 10 dB makes a sound seem about half as loud. However, factors other than distance also have effects.

Q: How can weather affect perception of freeway noise? A: Weather conditions, such as wind, can shift noise upwards or downwards.

Q: How do surfaces affect perception freeway noise? A: Like light, sound can be absorbed by some solid materials but bounce off and be redirected by other materials. Sound can also "bend" as it passes through holes or around obstacles. These and many other factors help determine the usefulness and construction of a soundwall.

Q: Are soundwalls the solution to freeway noise? A: Not always. Besides technical factors, other considerations arise, such as costs and visual impacts. These and additional issues will be addressed in articles to come.

May 5, 2011: Introducing the Sound Facts About Soundwalls series

Engineering studies for possible soundwalls along parts of SR-24 in the Rockridge area have been included on the final list of the Caldecott Fourth Bore Settlement projects. The subject of soundwalls in Rockridge has a long history, and has generated much discussion and many questions over the years. To determine whether these sound wall projects will continue to move forward, residents of affected parts of Rockridge will be polled for their opinions.

To help inform community discussion, the Rockridge Community Planning Council (RCPC) board is starting an outreach and educational initiative centered around a series of articles in The Rockridge News. The group will also organize community meetings for further discussion. RCPC seeks to provide a context for — and accurate information about — the characteristics, performance, and costs and benefits of soundwalls, before any residents are asked to make binding decisions about whether the walls should or should not be installed.

These articles will explore topics relevant to noise pollution and its mitigation including: tutorials on sound and hearing; noise and its measurement; socioeconomic, psychological, and physiological effects of noise; surface traffic and traffic noise; local, state, federal, and international guidelines for regulating noise; noise control, suppression, and mitigation; what soundwalls do and do not do, and how they do it; what soundwalls might look like, and what they might cost; a brief history of soundwall issues in Rockridge; and a description of the soundwall public process moving forward.

The articles will be edited and abridged for publication in The Rockridge News in subsequent months. Fuller and somewhat more technical versions will be posted as fact sheets on the RCPC website for readers' further review.

We will try to address your concerns in this series. If you have any specific questions or comments about soundwalls or noise pollution, please contact the RCPC board via or The Rockridge News via