HOW PIR HANDLES SOUND LEVELS:
In a 1989 agreement with North Portland neighborhood groups, Portland City Council recognized the importance of the track as a recreation and tourism site, while also acknowledging the negative sound impact on nearby neighborhoods from some events.
At that time, council:
Established the current sound limits which are still in place today (see below for limits and what they mean and what they equate to
Restricted normal track operations to levels consistent with City of Portland Code, meaning sound levels in the neighborhood meet code of 65 dB
Allowed for four “varianced” events per year that allowed race promoters to exceed the sound limits above for spectator events.
Set up a neighborhood trust fund whereby PIR agreed to contribute cash to a trust managed by North Portland Neighborhood Services for mitigation of those four louder events. These funds have been made available to the public via North Portland Neighborhood Services' annual grant cycle for community projects and events.
Daily Operation of the Track on Non-Varianced Days:
Except for four events, the track operates with the same noise restrictions as any industrial site in the city in relation to residences.
The maximum decibel level at trackside is 105 dBA, which in theory should translate to no more than 65 dB at the property line of the closest residence to the track. However, PIR governs participants to 103dBA.
In other words, except for four events, the track operates with the same noise restrictions as any industrial site in the city in relation to residences.
The four varianced events include one event at 110 dB, two at 112 dB and one at 115 dB. At a 115 dB level trackside:
Sound levels at the closest residence to PIR should be 70-75 dB
This equals normal traffic noise levels measured for homes along Columbia Boulevard
It is 10 dB higher than basic City Code allows for commercial/industrial noise to a residence.
There are two variance events approved for the 2017 season
115db: Portland Vintage Racing Festival weekend of July 27-30
112db: Columbia River Classic/All British Field Meet, weekend of September 2-3
Using all four varianced events, including test days, means fewer than 20 event days during the season where levels are above 105 dBA (2017 uses two of the four racing variances)
More than 500 event days per year run at or lower than 105 dBA. (Each particular event on a given day counts as an event day, i.e. a motorcycle track event during the day and a bicycle race at night would mean 2 event days.)
A great majority of event days operate at 90 dBA or less, meaning they aren’t audible at any point in the neighborhood, and if measurable would be 50 dBA or less in the neighborhood.
PIR Sound Levels in perspective with measurements in any given neighborhood:
Normal human conversation ranges between 44 and 65 dBA when people are about 3 to 6 feet apart
The smallest change in noise level that a human ear can perceive is about 3 dBA
For most people, a 10 dBA increase in noise levels is judged as a doubling of sound level, while a 10 dBA decrease in noise levels is perceived to be half as loud.
To put PIR sound levels in perspective with other common measurements:
100 dBA - Train warning horns at residences along Columbia Blvd.
90 dBA - Truck or motorcycle traffic in street outside residences
80 dBA - Heavy truck traffic noise at residences along Columbia Blvd.
80 dBA - Garbage disposal in a kitchen
75 dBA - Loudest variance (115dB variance) noise levels at closest residence
70 dBA - Average daytime noise levels residences along Columbia Blvd
70 dBA - Vacuum cleaner at 10 feet
60 dBA - Average nighttime noise levels along Columbia Blvd.
60 dBA - Normal PIR operations (105 limit) measured at closest residence
HOW PIR MONITORS SOUND LEVELS:
PIR operates a fixed microphone, 50 feet from the track, just past the “B” bleacher on the front straight. This spot was chosen by an independent noise consultant to best capture highest sound levels from the various kinds of events held at PIR.
The microphone is attached to a digital sound monitor. The data is then captured on a computer. All the noise files are held, and given to the City’s Noise Control Officer on request.
In addition to the fixed monitor, user groups are required to have a person in charge of events to monitor sound levels and remove vehicles from the track that exceed the limit (actually they use 103 dBA, rather than the code 105 dBA). Typically a vehicle that exceeds the limit is black flagged (taken off the track) and given a chance to make modifications or repairs to be below the limit. A second violation will mean a car will be removed from the competition or event for the rest of the day.
Should you have an issue with noise levels from the track, please call the track manager at 503.823.5899. You can also register a complaint with the City’s Noise Control Hotline at 503.823.7350.
User groups apply for one of the four noise variances through the City’s Noise Officer and the Noise Review Board, a citizen panel. Typically requests are made for one to three-year variances for the specific events in the winter and spring before the summer racing season. To find out about upcoming meetings call the Noise Control Hotline at 503.823.7350.
In 2006 Sam Adams, when he was a City Commissioner, asked for a study of both neighborhood opinions and a technical study of noise in North Portland as it relates to all noise generators, including train and truck traffic, airport noise and PIR operations. The technical study was managed by the Noise Control Officer.
The attitude study, done in 2006, with two phone surveys of North Portland residences, found:
10% of residents surveyed considered noise in the neighborhoods a significant issue saying it affected them a great deal.
The biggest issues for residents were loud music from cars or neighbors.
75% of residents said none of the local noise sources tested is a serious concern for them.
A majority of residents surveyed indicated that they are unaffected by noise from Portland International Raceway.
Downloadable Noise Survey report: