Chapter 17.156
TRAFFIC IMPACT ANALYSIS (TIA)
Sections:
17.156.020 Typical average daily trips and level-of-service standards.
17.156.040 Traffic impact analysis requirements.
17.156.070 Peak hour analysis.
17.156.090 Conditions of approval.
17.156.010 Purpose.
The purpose of this chapter is to implement OAR 660-012-0045(2)(e) of the State Transportation Planning Rule that requires the city to adopt a process to apply conditions to development proposals in order to protect and minimize adverse impacts to transportation facilities. This chapter establishes the standards for when a proposal must be reviewed for potential traffic impacts; when a traffic impact analysis must be submitted with a development application in order to determine whether conditions are needed to minimize impacts to and protect transportation facilities; what must be in a traffic impact analysis; and who is qualified to prepare the analysis. (Ord. 3150 § 3 (Att. B), 2011)
17.156.020 Typical average daily trips and level-of-service standards.
(1) The latest edition of the trip generation manual published by the Institute of Transportation Engineers (ITE) shall be used as standards by which to gauge average daily vehicle trips.
(2) Pursuant to the transportation systems plan (TSP) (see TSP Section 4), the following minimum operating standards apply to city-maintained intersections. As measured using the Highway Capacity Manual, latest edition, Level of Service “D” is considered acceptable at signalized and all-way stop controlled intersections if the intersection volume-to-capacity ratio is not higher than 1.0 for the sum of critical movements. Level of Service “E” is considered acceptable for the poorest operating approach at two-way stop intersections. Level of Service “F” is allowed in situations where a traffic signal is not warranted. (Ord. 3150 § 3 (Att. B), 2011)
17.156.030 Applicability.
A traffic impact analysis shall be required to be submitted to the city with a land use application when the application involves one or more of the following actions:
(1) A change in zoning or a comprehensive plan amendment designation, except when the change will result in a zone or plan designation that will result in less vehicle trips based on permitted uses (e.g., from a high density residential district to a lower density residential district or from a commercial district to a residential district);
(2) The site proposes to take access on Highway 30 or on an approach to Highway 30; or
(3) The development shall cause one or more of the following effects, which can be determined by field counts, site observation, traffic impact analysis or study, field measurements, crash history, Institute of Transportation Engineers Trip Generation, and information and studies provided by the local reviewing jurisdiction(s) and/or ODOT:
(a) The proposed action is estimated to generate 2501 average daily trips (ADT) or more or 25 or more weekday a.m. or p.m. peak hour trips (or as required by the city engineer);
(b) The proposed action is projected to further degrade mobility at the Deer Island Road/Highway 30, Pittsburg Road/Highway 30, Wyeth Street/Highway 30, Gable Road/Highway 30, or Millard Road/Highway 30 intersections;
(c) An increase in use of adjacent streets by vehicles exceeding the 20,000 pound gross vehicle weights by 10 vehicles or more per day;
(d) The location of the access driveway does not meet minimum intersection sight distance requirements, or is located where vehicles entering or leaving the property are restricted, or such vehicles queue or hesitate, creating a safety hazard;
(e) The location of the access driveway does not meet the access spacing standard of the roadway on which the driveway is located; or
(f) A change in internal traffic patterns that may cause safety problems, such as backup onto the highway or traffic crashes in the approach area. (Ord. 3150 § 3 (Att. B), 2011)
17.156.040 Traffic impact analysis requirements.
(1) Preparation. A traffic impact analysis shall be prepared by an Oregon registered professional engineer who is qualified to perform traffic engineering analysis and will be paid for by the applicant.
(2) Transportation Planning Rule Compliance. See SHMC 17.08.060, Transportation planning rule compliance.
(3) Pre-application Conference. The applicant will meet with the city engineer prior to submitting an application that requires a traffic impact analysis. The city has the discretion to determine the required elements of the TIA and the level of analysis expected. (Ord. 3150 § 3 (Att. B), 2011)
17.156.050 Study area.
The following facilities shall be included in the study area for all traffic impact analyses (unless modified by the city engineer):
(1) All site access points and intersections (signalized and unsignalized) adjacent to the proposed site. In particular, if the proposed site fronts an arterial or collector street, the analysis shall address all intersections and driveways along the site frontage, including those serving parcels on the opposite side of the street(s).
(2) Roads through and adjacent to site.
(3) Any intersection of two streets, each with a classification of collector or arterial, where site traffic will exceed 20 vehicles during a peak hour or, in the case of a rezone, if the trip differential resulting from the rezone will exceed 20 vehicles during a peak hour.
(4) All intersections needed for signal progression analysis.
(5) In addition to these requirements, the city engineer may determine any additional intersections or roadway links that may be adversely affected as a result of the proposed development. (Ord. 3150 § 3 (Att. B), 2011)
17.156.060 Analysis periods.
To adequately assess the impacts of a proposed land use action, the following study periods, or horizon years, should be addressed in the transportation impact analysis where applicable:
(1) Existing Year.
(2) Background Conditions, Future Year. The conditions in the year in which the proposed land use action will be completed and occupied, but without the expected traffic from the proposed land use action. This analysis should include all in-process developments, or city approved developments that are expected to be fully built out in the proposed land use action horizon year. It should also account for all in-process/planned transportation system improvements.
(a) Depending on funding or project development issues, it may not be appropriate to assume that certain planned transportation system improvements will be in place on opening day. Applicants should contact the city engineer to confirm appropriate assumptions.
(3) Full Buildout. The background condition plus traffic from the proposed land use action assuming full buildout and occupancy.
(4) Phased Years of Completion. If the project involves construction or occupancy in phases or for master plans, the applicant shall assess the expected roadway, intersection, and land use conditions resulting from major development phases. Phased years of analysis will be determined in coordination with city staff.
(5) Twenty-Year or TSP Horizon Year. For master plans, zone changes, and conditional uses, the applicant shall assess the expected future roadway, intersection, and land use conditions resulting from deviations from approved comprehensive planning documents. A 20-year or TSP horizon year analysis will not be required for outright permitted uses under the current zoning. (Ord. 3150 § 3 (Att. B), 2011)
17.156.070 Peak hour analysis.
(1) The traffic impact analysis shall address the weekday a.m. and p.m. peak hours when the proposed land use action is expected to generate 25 trips or more during the peak time periods. If the applicant can demonstrate that the peak hour trip generation of the proposed land use action is fewer than 25 trips during one of the two peak study periods and the peak trip generation of the land use action corresponds to the roadway system peak, then only the worse of the two peak periods must be analyzed.
This does not mean, however, that all aspects of the other peak period can be ignored. The applicant should consider, for example, the possibility that inbound and outbound trips at the site driveway have specific operational issues that may need to be addressed for both peak hours.
(2) Depending upon the proposed land use action and the expected trip generating characteristics of that development, other time periods may be specified, either as a substitute for or in addition to the a.m. and p.m. peak hours. Examples of land uses that have nontypical trip generating characteristics include schools, movie theaters, and churches. Applicants should assume that the city will require additional analysis periods for certain uses as summarized below:
(a) Schools: End of the school day (early afternoon) peak hour.
(b) Churches and worship facilities: Peak period prior to and after worship services.
(c) Restaurants: Midday weekday peak hour.
(d) Theaters: Friday theater peak hour.
The above list is not necessarily an all-inclusive list of uses for which additional analysis periods is required. The city engineer and applicant should discuss the potential for additional study periods prior to the start of the traffic impact analysis. (Ord. 3150 § 3 (Att. B), 2011)
17.156.080 Approval criteria.
When a traffic impact analysis is required, approval of the development proposal requires satisfaction of the following criteria:
(1) The traffic impact analysis was prepared by an Oregon registered professional engineer using the analysis procedures of the Highway Capacity Manual, latest edition;
(2) If the proposed development shall cause one or more of the effects per SHMC 17.156.030 or other traffic hazard or negative impact to a transportation facility, the traffic impact analysis shall include mitigation measures that meet the city’s adopted level-of-service standards (per the transportation systems plan and noted under SHMC 17.156.020) and are satisfactory to the city engineer and ODOT, when applicable; and
(3) The proposed site design and traffic and circulation design and facilities for all transportation modes, including any mitigation measures, are designed to:
(a) Have the least negative impact on all applicable transportation facilities;
(b) Accommodate and encourage non-motor vehicular modes of transportation to the extent practicable;
(c) Make the most efficient use of land and public facilities as practicable;
(d) Provide the most direct, safe and convenient routes practicable between on-site destinations, and between on-site and off-site destinations; and
(e) Otherwise comply with applicable requirements of the SHMC. (Ord. 3150 § 3 (Att. B), 2011)
17.156.090 Conditions of approval.
The city may deny, approve, or approve a development proposal with appropriate conditions needed to meet operations and safety standards and provide the necessary right-of-way and improvements to develop the future planned transportation system. Conditions of approval that should be evaluated as part of land divisions, conditional use permits, and site development reviews include:
(1) Crossover or reciprocal easement agreements for all adjoining parcels to facilitate future access between parcels.
(2) Access for new developments that have proposed access points that do not meet the designated access spacing policy and/or have the ability to align with opposing access driveways.
(3) Right-of-way dedications for future planned roadway improvements.
(4) Half-street improvements along site frontages that do not have full-buildout improvements in place at the time of development. (Ord. 3150 § 3 (Att. B), 2011)
As an example, 250 ADT is roughly equivalent to 25 single-family homes, 37 apartments, 22,000 square feet of office space, or a 2,300 square foot supermarket. This example is not a substitute for determination of vehicle trips per SHMC 17.156.020.