Frequently Asked Questions - Public Works
Speed Zones

Q: How are speed zones determined?

A: Your own neighborhood, or work area, you want people to travel at a slow-to-moderate speed. If you're driving through someone else's neighborhood or work area, you want to travel quickly and smoothly.

A solution to the problem of local resident versus driver has been sought for years. Our speed zone laws are based upon logic, human tendencies, engineering studies, and the belief that most people are reasonable. The speed limits we post follow this idea.

Lower posted speeds do not result in lower traveled speeds. Setting unrealistically low speeds frustrates drivers, resulting in more violations and causing more accidents. It also encourages disrespect for the law in general.

The "Basic Rule"
In Oregon, there are five designated speed zone standards set by state law:
15 mph - alleys
20 mph - business districts, and school zones when children are present
25 mph - residential districts, public parks, and ocean shores
55 mph - open and rural highways, urban interstate highways, and trucks on rural interstate highways
65 mph - autos on rural interstate highways

These standards are overruled by posted speed zones, but the final word for all travel on public roads is the Basic Rule, which states that a motorist must drive at a speed that is reasonable and prudent, at all times, by considering traffic, road, weather and other conditions that affect safety and speed. The Basic Rule does not allow motorists to drive faster than posted or designated speed, nor does it set speed zones.

Establishing a Speed Zone
The Oregon State Department of Transportation  (ODOT) has the responsibility to investigate roads at the request of the County for speed zones changes, and to make recommendations following established standards. These recommendations are reviewed by the County.

If the County agrees with the recommendations, the speed zone is established. If not, ODOT reviews the County's objections and any additional information. ODOT may then revise its recommendation.

If no agreement can be reached, the speed zone decision is referred to a five-member hearings panel that reviews the information and receives testimony from interested parties. The panel makes the final decision. It includes representatives from the Oregon Transportation Safety Committee, Oregon State Police, Association of Oregon Counties, League of Oregon Cities, and ODOT.

Speed zones may be established only on county-maintained roads. ODOT does not normally conduct speed zone investigations on lightly-traveled roads or unsurfaced roads.

Criteria for posting speeds
When ODOT considers a request from the County to establish or change speed zones, an engineering study is done on the road in question. Traffic information is collected on factors such as the number and type of vehicles that use the road during different periods of time.

Radar may be used for spot speed tests to determine the prevailing speed drivers are traveling on the road. Studies have shown that most drivers are careful and prudent, and engineers often will choose a limit at, or below, the speed traveled by 85 percent of all drivers. Studies across the country have shown that this speed, which engineers call the "85th percentile", is a fair and objective indication of a safe and reasonable speed.

ODOT's engineering report also will include roadway measurements and features, photos, and a history of traffic accidents. When all the studies are completed, ODOT weighs all the factors and decides whether to establish a posted zone. Their objective is to set reasonable speeds using impartial judgment.

Speed zones can help traffic move more safety and efficiently, but speed zones should not be regarded as a quick fix. Speed zones are a reasonable compromise between the needs of drivers and those who live along the roadways.

How does the petition process work?
A resident interested in a speed zone contacts a representative from Public Works. Topics for discussion include the specific portion of road to be studied, the existing speed limit, and the "functional classification" of the road.

The functional classification of a road is a measure of the level of service the road is expected to provide to the community. There are three road classifications: residential, collector and arterial. An arterial or collector may provide direct access to a limited number of residences but this does not alter its classifications.

A petition will be generated when the resident and the Public Works representative agree that a speed zone study is appropriate, and agree on a proposed speed. The resident will be responsible for circulating the petition and collecting signatures from at least one-third of the owners of property that abuts the road or section of road to be studied.

What happens next?
The Board of County Commissioners will consider the petition, and at their discretion, may submit a request to the Oregon Department of Transportation to determine the designated speed that is reasonable and safe under the conditions of the area. In their request to ODOT, the Commissioners may request a speed greater or less than the petitioners' request.

After ODOT delivers its report on the petition to the County Commissioners, ODOT may then proceed officially to adopt an order establishing the new designated speed zone.

Who posts new speed limit signs?
If ODOT establishes a new speed limit, the County may then post appropriate signs designating the new speed limit on the road, and drivers would be subject to the new speed limit.

For more information, contact  or call 541-474-5460.

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