Land Use and Transportation Program
Transportation Planning Development Review for
This brochure provides information on the transportation planning review process and the types
of transportation-related requirements for development.
When you submit a land use or building permit application to the County, it will be reviewed by
transportation planning for compliance with Multnomah County Transportation Policies, County
Road Rules and the County’s Design and Construction Manual.
Why is transportation planning review required?
The purpose of transportation planning review is to identify any development-created impacts on
the transportation system and necessary mitigation measures.
What triggers transportation planning review?
Generally, a transportation impact, as defined by the County Road Rules, triggers transportation
planning review. Review may also be triggered when a new or altered access to a road under
County jurisdiction is proposed.
What is a transportation impact?
A transportation impact is defined by the Road Rules as any new construction or alteration which
increases the number of trips generated by a site by more than 20 percent, by more than 100
trips per day or by more than 10 trips in the peak hour. A minimum increase of 10 new trips per
day is required to find a transportation impact.
For example, construction of a new single-family home on a vacant lot will generate 10 new trips
(a single-family home generates 10 trips per day on average) and create a transportation impact.
Construction of a residential addition or a replacement home will not generate any new trips, and
therefore, will not create a transportation impact as defined by the County’s Road Rules.
Will I have to dedicate part of my property?
Dedication of property for public purposes is sometimes required as part of a land division or
development project. As a condition of approval, you may be required to dedicate a portion of
your property for future street improvements, pedestrian or bike facilities, drainage, or other
utilities as part of your project.
If a culvert exists under a County Road adjacent to your property, you may be asked to dedicate
the necessary slope/drainage easement to the County to allow the County to maintain the culvert
and prevent culvert failure and property damage in the future. The standard size for a
slope/drainage easement centered on a culvert is 25 feet by 25 feet; however, this may vary by
property depending on the terrain.
If a right-of-way dedication is required from your property, the amount and type of dedication will
be proportional to the impact of your project.
What improvements will I have to make to the right of way?
Depending on the impact of your project, additional right-of-way improvements may be required.
Improvements may include, but are not limited to, shoulder/pavement widening, traffic control,
landscaping, driveway removal or relocation, and bicycle and pedestrian facilities.
Standard improvements for rural driveways typically include 20-foot paved (asphalt) approach to
the County Road.
In order to determine the impact of your project, you will be required to submit a description of the
proposed use of your property. Additional information may be required such as the number and
location of existing and planned access points, existing roadway conditions in the vicinity of your
site, and/or estimated trip generation. In some instances a traffic impact analysis (TIA) may be
required to determine mitigation measures.
What restrictions are there for access?
One driveway access per property is the standard for approval. Double frontage lots are limited to
access from the lower classification street. Shared access may be required in situations where
spacing standards cannot be met or where there is a benefit to the transportation system.
Driveway placement and design will be determined based on standards in the County’s Design
and Construction Manual and the American Association of State Highway and Transportation
Officials’ A Policy on Geometric Design of Highways and Streets. All new access points to roads
under the County’s jurisdiction must meet minimum sight distance standards. Vegetation
trimming or earth movement may be required to achieve needed sight distance.
Submittal of sight distance certification by a registered traffic engineer may be required as part of
What kinds of permits will be required?
An access/encroachment permit is required for the following: (1) new or altered access to roads
under County jurisdiction, (2) structures in the right-of-way, such as signs, posts, fences, flags,
nonstandard mailboxes, etc., or (3) any other minor physical alteration of the County right-of-way,
including but not limited to any altered landscape design, vegetation planting or placement.
A Construction Permit is required for any activity in the right of way that involves the construction
of a facility, structure or otherwise permanently alters any physical aspect of the right of way,
except for those activities covered under an Access/Encroachment Permit.
Other permits may be required such as a sewer connection permit, utility permit, etc.
I want to build a single-family residence on my property, what will I be required to do?
While it is difficult to say exactly what will be required since each property is different, generally
the following conditions are required for construction of a new home in rural areas:
1. An access/encroachment (driveway) permit.
2. A 20-foot paved approach to the County Road.
3. Sight-distance verification.
4. Slope/drainage easement dedication if a culvert exists adjacent to your property along the
5. Additional right-of-way dedication may be required to meet the current County standard.
County Transportation may require additional measures based on any unique characteristics of
your property. Please contact County Transportation Planning staff to determine requirements.
I live on a Local Access Road, what improvements will I be required to make?
Most new developments that take access from a Local Access Road and are found to have a
transportation impact will require the developer to improve the Local Access Road. The
developer may be required to make appropriate improvements along the frontage of the
developed property or a greater distance if the transportation impact warrants additional road
When and how will I be required to meet the transportation conditions?
Requirements for traffic studies, sight distance certification, or additional property information
may be required prior to the land use decision. Requirements for right-of-way dedication and/or
permits must be completed prior to issuance of a building permit or plat approval.
County Transportation will determine the appropriate method(s) to satisfy the improvement
requirement(s), which may include one or a combination of the following: construction permit or
project agreement, payment in-lieu-of construction, and/or a non-remonstrance agreement
obligating the property owner and any successors in interests to share in the cost of the
What if I can’t meet the standards or requirements?
The County Engineer can allow for a variance from County standards and requirements when
written documentation substantiates that the requested variance is in keeping with the intent and
purpose of County Code and adopted rules, and the requested variance will not adversely affect
the intended function of the County Road system or related facilities. The variance procedure is
described under Multnomah County Road Rules Section 16.000.
Contact Multnomah County Transportation Planning (Development Review) at (503) 988-5050
extension 29637 for more information.