Transportation Engineering

1. All driveways shall meet ADA accessibility requirements if the driveway intersects with a planned or existing sidewalk or other pedestrian facility.
2. Driveways should be designed with a minimum 28-foot wide approach except where the Comprehensive Plan requires narrower driveways.
3. If the design vehicle for the site requires it per Section 250.1.3 or if traffic operations necessitate additional travel lanes, driveways wider than 28 feet may be required to reduce the pedestrian crossing length or implement additional measures to reduce conflicts with pedestrians.
4. Driveways on streets with curb tight sidewalk should be constructed per Standard Drawing D600. 
5. Driveways on streets with curb and sidewalk with a landscape strip should be constructed per Standard Drawing D650. 
6. In rare cases where a development's trip generation is such that higher speed egress maneuvers from the adjacent roadway are desired or is used for a large number of truck deliveries, the County may allow or require driveways to be constructed per Standard Drawing D675.
7. Driveways constructed without curbs should be constructed per Standard Drawing D500.
8. Driveway throats (measured from the back of the public sidewalk in the UGB and from the edge of pavement outside the UGB to the nearest perpendicular drive aisle) shall have a minimum length of 20 feet but should be designed to accommodate the 95th percentile queue.  Driveway throat depths may be required to be based upon a traffic study per Section 295.
9. Driveways accessed by trucks with trailers, should require a minimum throat length of 50 feet.
10. Parking, intersecting drive aisles and designated pedestrian crossings are prohibited within the minimum throat depth.
11. If a gate is proposed on a driveway serving the public, the gate shall be placed a minimum of 20 feet from back of sidewalk or edge of pavement, whichever is greater.  If queues are likely to extend into the travel lane of the nearest roadway, then a queuing analysis shall be provided per Section 295.  Gates may require the approval of the fire district. 
12. Gates are required to have a minimum of a 20' wide unobstructed opening.  The opening width will be required to increase when the length of the anticipated vehicle increases unless the gate is set back far enough for the vehicle to be perpendicular to the gate.

320.1 Maximum Slopes and Grades

1. The plan review, permit and inspections for ADA improvements will be covered under a Development Permit when they are not related to a building permit under review.
2. The ADA facilities should be designed with a 0.5% tolerance from maximum slopes and grades.
3. General parking areas and adjacent drive aisle slopes should not exceed +/-5%.
4. Drive aisles not adjacent to parking spaces should not exceed a longitudinal slope of 10%.  Cross slopes shall not exceed 5%.

320.2 Pedestrian Walkways

1. Walkway connections to the public sidewalk shall meet ADA landing area requirements per PROWAG and be reviewed and permitted by Engineering.
2. Onsite accessible routes, when permitted through a Development Permit, shall meet the requirements of the latest version of the Oregon Structural Specialty Code (OSSC) Chapter 11 and the International Code Council (ICC) A117.1.

320.3 Vehicular Circulation and Maneuvering

All vehicle maneuvering shall be provided on site and should limit backing maneuvers in locations where pedestrians are expected.

1. For dimensions of parking spaces and drive aisles refer to Standard Drawings P100 and P200.
2. To be considered a parking space, adequate maneuvering area shall be provided for each vehicle to enter and exit said parking space.
3. All garbage and recycling facilities shall have adequate access, with onsite maneuvering and circulation for the service provider's vehicle.
4. All movements for non-passenger design vehicles should be shown on an exhibit, showing paths traced by the extremities of the vehicles, including off-tracking.  Adequate turning radii shall be provided for all loading spaces and the largest anticipated vehicles maneuvering on site and at driveway approaches.  At a minimum, the circulation of a fire truck and garbage truck shall be illustrated.

320.4 Parking and Maneuvering Area Surface & Structural Section

1. The parking and maneuvering surface (gravel or paving) shall comply with ZDO Section 1015 or with Standard Drawing R100 if not related to development. 
2. The structural section of parking and drive aisle areas shall meet or exceed Standard Drawing R100.
    

320.5 Parking Stalls

1. All automobile off-street parking quantity and dimensions shall meet the ZDO and Roadway Standard Drawing P100 or P200
2. Dimensions for on-street parking spaces shall meet or exceed the requirements of Roadway Standard Drawing P100 or P200.  The on-street parking shall utilize the street for the drive aisle.  The parking spaces shall not diminish or obstruct the required travel lanes or bike lanes.
3. All compact, carpool, disabled, and loading berth spaces shall be labeled on the plans. 
4. Accessible parking spaces shall meet the requirements of the Oregon Transportation Commission's Standards for Accessible Parking Places, latest edition.

320.6 Curbs and Wheel Stops

1. If parking lot curbs carry, direct or channel surface water, the curb should be structural curb. 
2. Alternative curbs will be considered when it is determined by Engineering that structural curb is not the most appropriate.
3. Extruded curbs shall not be used for carrying, directing or channeling surface water, or as a vehicle wheel stop.

320.7 Signage and Pavement Markings

1. All traffic control devices on private property shall be installed and maintained by the property owner.  Traffic control devices that are located where private driveways intersect a road right-of-way shall be kept in good condition. 
2. The applicant shall provide a signing and pavement marking plan to Engineering for onsite parking and circulation.  This plan shall be reviewed and approved by Engineering and the local fire service provider prior to the applicant being issued a Development Permit.
3. All compact, carpool, disabled parking spaces shall be clearly marked on the site.

320.8 Reciprocal Access Easements

Comply with Section 220.

Chapter 3 establishes the technical requirements associated with on site design of commercial, industrial and multifamily developments  

Site improvements for commercial, industrial, and multifamily developments are reviewed through the land use approval process, described and administered pursuant to the ZDO. 

This chapter supplements the requirements of the ZDO, which contain greater detail in relation to onsite design of commercial, industrial and multifamily developments.

295.1 General

The objective of a transportation impact study (TIS) is to assess the impacts of a proposed project or land use action on the transportation system and identify mitigation for any capacity or safety deficiencies.  These requirements are intended to provide standards for generation of a TIS for land development applications that are consistent with land use regulations and guidelines for traffic analysis that is prepared for County capital projects.   

295.2 Requirement for a Traffic Impact Study

1. A TIS shall be required based upon an assessment of Engineering regarding the anticipated relative impact of a proposed development on the existing or planned transportation system. 
2. A TIS to address traffic capacity is not required where the proposed development will generate less than twenty vehicles trips in any peak hour unless to address specific safety issues identified by the County.  The need for a TIS is at the discretion of the Road Official.

295.3 Traffic Study Scope and Coordination

1. Engineering and the applicant should coordinate to develop a written TIS scope that will guide the work of the TIS and define the study requirements based upon the anticipated influence area of the proposed development.
2. The influence area of a proposed development establishes the requirements of analysis for the TIS and is defined on a case by case basis, but is typically based upon the trip generation of the proposed development in relation to the proximity of congested roadways and intersections or the proposed development's potential impact on safety issues.

295.4 Traffic Engineering Expertise

All traffic impact studies shall be conducted under the direction of and stamped by an Engineer with expertise in traffic engineering. 

295.5 Coordination with Other Agencies

As applicable, the applicant is expected to coordinate with ODOT and affected local jurisdictions in the scoping, development, and review of a TIS regarding intersections or roadways that are not under the County's jurisdiction.  In some cases, the County has adopted adjacent agency standards as part of the ZDO.

295.6 Zone Changes and Comprehensive Plan Amendments

Zone changes and Comprehensive Plan amendments require analysis compliant with OAR 660-012-0060, the Transportation Planning Rule.  

295.7 Clackamas Regional Center (CRC) Area Analysis Period

1. The ZDO and Comprehensive Plan Chapter 10 require special analysis periods within the Clackamas Regional Center Area. 
2. Within the CRC area, a weekday PM peak two hour analysis is required.  The first hour of analysis shall be based upon the peak hour of the subject intersections.  If the mobility standard is met for the first hour, no further analysis is required.  If the mobility standard is not met in the first hour, a second hour of analysis is required.  The second hour of analysis shall be based upon the "shoulder" ½ hours before and after the peak hour, which may require additional traffic counts.
3. Within the CRC area, a weekday midday hour analysis is required.

295.8 Analysis Methodology

1. All analyses shall be conducted in compliance with the most recent versions of the following:
2. Highway Capacity Manual (HCM) with the exception of signalized intersections, which shall be based upon the HCM 2000
3. ITE Trip Generation Manual
4. ITE Trip Generation Handbook
5. MUTCD
6. AASHTO - A Policy on the Geometric Design of Highways and Streets
7. AASHTO - Guidelines for Geometric Design of Very Low-Volume Local Roads
8. AASHTO - Highway Safety Manual
9. It is recognized that in many instances, the HCM's methodology is limited especially in highly congested conditions.  In instances where the HCM is incapable of providing accurate analysis, the County and applicant shall coordinate on an appropriate analysis method.
10. The following establish the County's LOS and v/c determination method and other analysis parameters required to evaluate the requirements of the Comprehensive Plan and ZDO. 

295.8.1 Two-Way Stop Controlled (TWSC) Intersections

At two-way stop controlled intersections, including driveways, the weighted average methodology of the critical approach of the HCM shall determine the LOS and v/c of the intersection. 

295.8.2 All-Way Stop Controlled (AWSC) Intersections

At all-way stop controlled intersections, the intersection average methodology of the HCM shall determine the LOS and v/c of the intersection. 

295.8.3 Signalized Intersections

At signalized intersections, the intersection average methodology of the HCM shall determine the LOS and v/c of the intersection.

295.8.4 Roundabout Intersections

At roundabouts, the critical approach shall determine the LOS and v/c of the intersection.

295.9 Signalized Intersection Analysis Parameters

1. The TIS shall analyze traffic signals in the following manner with regard to traffic signal timing:
2. The existing, background and total traffic analysis shall be consistent with the existing signal timing. 
3. Analysis of isolated intersections shall optimize the existing splits within the maximum cycle length.
4. Signals that operate in a coordinated timing plan shall be analyzed without adjustments.
5. If modifications to the signal timing are proposed or shown in the analysis, the total traffic analysis shall contain two scenarios:  total traffic with existing signal timing and total traffic with proposed signal timing.  However, signal timing modifications are typically not acceptable as mitigation to a project's impacts.
6. Additional analysis requirements may apply in the case of coordinated signal systems as changes at one intersection may affect other intersections not included in the study area of the project.
7. The Engineer shall request County, ODOT and local jurisdiction signal timing for use in their analysis.  The Engineer is responsible for ensuring that the appropriate signal timing is used in the analysis.
8. If signal timing changes are recommended by the applicant and approved by Engineering as acceptable mitigation to a project's impacts, funds will be required to design and implement new signal timing plans suggested as mitigation by the applicant.
9. Where adaptive signal timing exists, the applicant and County will work together to determine the appropriate signal timing parameters.

295.10 Peak Hour Factor ("PHF")

1. The peak 15 minutes of the peak hour shall be the basis for determining intersection operations except as noted in the ZDO and Comprehensive Plan, which allows a one hour peak period in some situations.  In those instances, the peak hour factor shall be set to 1.0 and the entire peak hour traffic volume shall be evaluated. 
2. The PHF shall be derived from the existing raw manual turning movement counts and be applied uniformly over each scenario except as provided below in 3).
3. In the case of zone change or comprehensive plan amendment analysis, the peak hour factors presented in ODOT's Development Review Guidelines or existing PHF shall be used in analysis.  

295.11 Microsimulation Models

1. Congested conditions will require the use of microsimulation models.
2. The use of microsimulation shall require compliance with the ODOT Analysis Procedures Manual (APM)

295.12 Growth Rates and In Process Traffic

1. For short term analysis of five years or less, linear growth rates shall not be less than 2% per year unless verifiable evidence is submitted or known which indicates that the local growth rate is less than 2% per year.
2. For long term analysis of six years or more, linear growth rates should not be used if regional travel demand volumes are available.  In that case, the analysis should rely upon regional travel demand volumes and post process those volumes per the APM.  If no regional travel demand volumes are available, the historical trends methodology of the APM or other approved methodology may be acceptable.
3. In process traffic, or developments that have been approved and have current land use approval yet are not occupied or fully built-out, shall be included in addition to growth projections.  That information may be omitted for zone changes and comprehensive plan amendments.

295.13 Turning Movement Counts

Turning movement counts shall be conducted as follows:

295.13.1 Count Hours

The count hours stated in Table 2-19 shall be collected in analysis unless the TIS scope specifies otherwise.

295.13.2 Day of Week

Turning movement counts shall be conducted on Tuesdays, Wednesdays and Thursdays unless otherwise directed.

295.13.3 Holidays

Turning movement counts shall not be conducted within one week of a federal holiday.

295.13.4 Current Counts

Traffic counts should be based upon counts collected within 24 months of the completed land use application.  Counts older than 24 months may not be accepted or may require adjustment to current traffic conditions with Engineering approval.

295.13.5 Vehicle Classification, Bicycles and Pedestrian Data

Turning movement counts shall separately include vehicular (truck vs. non-truck), bicycle and pedestrian traffic volumes.

295.14 Trip Generation

1. Trip generation shall be based upon the latest edition of ITE's Trip Generation Manual and Trip Generation Handbook. 
2. The traffic impact study shall include an estimate of site generated trips, pass-by trips, diverted linked trips, and internal capture trips during each study period.
3. If a trip generation rate similar to the proposed use is not available within Trip Generation Manual, then the procedures of the Trip Generation Handbook regarding obtaining local trip rates should be used unless otherwise approved by Engineering.  Engineering may require evidence that the use's trip generation is similar to the use described in the Trip Generation Manual.
4. Trip generation shall be based upon an average weekday unless otherwise specified by Engineering.

295.15 Trip Distribution

Trip distribution shall be approved by Engineering.

295.16 Queuing Analysis

1. All development may be required to provide a queuing analysis that evaluates the impact of queues onto public roadways.  Developments that are anticipated to back traffic onto public roadways are considered to be a safety issue. 
2. Development that proposes a drive-thru service shall provide a queuing analysis that evaluates the impact of drive-thru queues onto public roadways.
3. As required by Engineering, the TIS shall provide 95th percentile queue estimates for each movement at each study intersection.  The TIS shall identify the existing available queue storage, anticipated 95th percentile queue and indicate if that storage is or will be exceeded.
4. In cases where the anticipated 95th percentile queue exceeds the available storage and the queuing is considered to be a safety issue, the development will be required to mitigate a queue back to the background traffic condition.
5. Microsimulation utilized to substantiate queuing shall comply with Section 295.11.

295.17 Traffic Safety

If required, the TIS shall analyze the safety of the transportation network by addressing the following.  If any of these conditions cannot be met and mitigation does not sufficiently address the deficiencies, Engineering may recommend that a proposed development does not meet safety standards:

1. Sight distance is adequate subject to the standards of Section 240.
2. Crash history is adequate per Section 295.17.1.
3. Queuing is adequate per Section 295.16.
4. Access requirements are adequate per Section 220.
5. A turn lane, if warranted and recommended by Engineering per Section 295.18.1, is provided. 
6. Truck circulation is adequate per Section 295.17.2.
7. Off-site access is adequate per Sections 225.4 and 225.5.

295.17.1 Crash History

1. Crash history shall be analyzed for all study intersections and sections of roadway to which access is proposed.  Crash rates, frequency and severity shall be evaluated.
2. The applicant shall evaluate the existing crash history to determine crash patterns, severity and frequency and make recommendations for safety improvements. 
3. Intersection crash rates in excess of typical crash rates require further safety analysis based upon the Highway Safety Manual the APM to determine the development's impact on safety and may require proportional mitigation. 
4. As required, segment crash rates in excess of typical crash rates require further safety analysis based upon the Highway Safety Manual and the APM to determine the development's impact on safety and may require proportional mitigation. 

295.17.2 Truck Circulation

1. For developments that will generate greater than 50 daily vehicles of a size greater than or equal to WB-50, an analysis of truck turning movements at the intersection of the following will be required:
   1. The nearest collector or arterial roadway (whichever is closer) if within the UGB.
   2. With the nearest arterial roadway if outside the UGB.
2. Mitigation will be required if a safety issue would result.

295.18 Mitigation

1. The traffic study shall include suggested mitigation to comply with ZDO and Comprehensive Plan mobility requirements, to provide a minimum level of safety to support the proposed development and to address other requirements of these Standards as required. 
2. Proposed mitigation may require a safety analysis based upon the Highway Safety Manual and APM.
3. Mitigation that shall be considered in the analysis is described below, as applicable:

295.18.1 Turn Lane Warrants

1. The applicant shall analyze the need for right and left turn lane warrants as required by Engineering. 
2. The County utilizes the current ODOT left turn and right turn siting criteria of the Highway Design Manual when establishing the possible need for left and right turn lanes. 
3. The affirmation of a warrant being met for a turn lane does not dictate its installation.  County staff will make a determination regarding the need for turn lanes.
4. Signalized intersections shall be accompanied by channelized left turn lanes on the major street and minor street and designed per Section 250.8.8 except as approved per Section 170.
5. Signalized intersections may require channelized right turn lanes as warranted above and designed per Section 250.8.8.

295.18.2 Traffic Signal Approval

A traffic signal proposed to address safety or capacity issues shall meet the requirements of Section 260 including evidence to indicate that other alternatives have been considered. 

295.18.3 Analysis of Impacts on Local, Residential Streets

1. Some developments may have a detrimental effect upon existing residential uses.  As applicable, the TIS shall evaluate impacts such as traffic volume increases, potential speed increases, safety impacts and other livability issues on local, residential streets. 
2. Based upon the relative impact of the development upon local, residential streets,  improvements to mitigate a development's impact may be required. 
3. Elements to be considered as potential mitigation include the traffic calming measures of Section 265.

295.18.4 Other Mitigation

Other mitigation, such as the installation of stop signs, warning signs, signal timing modifications, additional lanes, roundabouts, traffic circles, pedestrian and bicycle improvements and other potential improvements, will be evaluated on a case by case basis.  Suggested mitigation shall be accompanied by appropriate engineering analysis to allow for the review of such proposals including a review of the mobility and safety impacts of the proposed mitigation. 

295.19 Traffic Study Components

The following elements typically make up a TIS.

295.19.1 Executive Summary

An executive summary that discusses the proposal and the results of the study and any necessary traffic related mitigation to meet the requirements of the land use application.

295.19.2 Project and Study Area Description

A description of the existing and proposed land uses, site characteristics, surrounding land uses, roadway system characteristics, transit service, pedestrian and bicycle facilities, and any pending transportation system improvements as identified in the Clackamas County Capital Improvement Program, Comprehensive Plan, and ODOT or local jurisdiction plans.

295.19.3 Analysis Periods and Scope

1. Analysis of intersection capacity and/or roadway segment capacity, as required by the Scope, meeting the requirements of these Standards, ZDO and Comprehensive Plan. 
2. The analysis shall include the following study scenarios at a minimum or as directed by staff:
3. Existing Traffic (Analysis based upon "current" traffic counts)
4. Background Traffic at a reasonable full build-out year (Existing Traffic + Growth + In Process Traffic)
5. Total Traffic at a reasonable full build-out year (Background Traffic + Site Generated Traffic)

295.20 Submittal Requirements

1. Completed traffic studies and revisions shall be submitted as a pdf document.
2. All electronic files used in support of a traffic analysis shall be submitted upon request.

290.1 General

1. Traffic control in the public right-of-way is subject to a permit.
2. All traffic control shall comply with the requirements of the MUTCD, Oregon MUTCD supplement, the ODOT Sign Policy and Guidelines, FHWA's Standard Highway Signs, Oregon Standard Specifications for Construction, Oregon Temporary Traffic Control Handbook for Operations of Three Days or Less, and Oregon Traffic Control Plans Design Manual. Oregon Standard Drawings TM800 series should be used with particular reference to TM844 for temporary pedestrian access routes.
3. Traffic control plans need not generally bear the stamp of an Engineer, except as required by Engineering.  If required due to complexity, plans shall be prepared under the direction of and stamped by an Engineer with expertise in traffic engineering.

290.2 Control of Site

1. At no time shall flagging operations delay traffic for a period greater than twenty (20) minutes.
2. Work and activity zones (construction, restoration, erosion control) shall extend no more than 2500 lineal feet at any one time unless otherwise approved.
3. Open trenches shall extend no more than 250 lineal feet at any one time, unless otherwise approved. 
4. No trenches are to be left unprotected between dusk and dawn.
5. Trenches shall conform to the technical requirements of Section 00405 of the Oregon Standard Specifications for Construction.
6. Trench plating shall be positively secured from movement and shall be ramped with anti-skid coated plate ramps.

290.3 Temporary Pedestrian Accessible Route

If existing pedestrian access will be obstructed by construction, alteration, maintenance or other temporary conditions, a continuous temporary pedestrian accessible route (TPAR) shall be provided consistent with the requirements of this section. Temporary pedestrian accessible routes shall conform to the requirements of Part 6 of the MUTCD, and the most recent update of the Oregon Standard Specifications for Construction, Section 00220.02(b). The temporary pedestrian accessible route plan shall be included in the traffic control plans. County inspectors will inspect the TPAR. If deficiencies are identified the inspector will stop work until such deficiencies are corrected.  TPAR requirements include:

1. In work zones pedestrian access shall not be blocked by parking of vehicles or equipment, materials storage or for any other reason except for construction.
2. The TPAR shall parallel the disrupted pedestrian access route, on the same side of the street where possible.
3. Bicyclists should not routed into the TPAR. If it is necessary to divert bicyclists around the work, provision should be made for a separate route for bicyclists.
4. If the work impacts the accessibility of pedestrian routes through or around the work zone, limit impacts to one corner of an intersection at a time.
5. Close sidewalk at a point where there is an alternate way to proceed and provide signing and other traffic control devices directing pedestrians to an alternate pedestrian route. 
6. The TPAR shall be inspected by the applicant on a regular basis to ensure that it is safe and does not have gaps or surface displacements creating a hazard. 
7. The TPAR shall meet the standards of a pedestrian access route as defined in PROWAG:
   1. Minimum width shall be 48 inches. Provide a 60 by-60 inch passing space every 200 feet along the route.
   2. Surface shall be smooth and nonslip.
   3. Vertical clearance shall be at least 8 feet.
   4. Cross slope shall be no more than 2.0% perpendicular to the direction of pedestrian travel.
   5. Grade shall be less than or equal to the grade of the adjacent road.
   6. Minimum turning space of 4 feet by 4 feet shall be provided wherever it is necessary for pedestrians to turn.
   7. If it is necessary to cross a curb, the TPAR shall include a temporary ramp meeting standards for a curb ramp.
   8. If it is necessary for the TPAR to cross a driveway or construction access truncated dome warning shall be provided. If it is not possible to provide truncated dome warning construction staff shall be provided at all times when construction vehicles are crossing the pedestrian access route.
   9. Night time lighting shall be provided.
8. Provide and maintain Pedestrian Channelizing Devices (PCD) through the period in which the permanent pedestrian access route is disrupted. Pedestrian channelizing devices are intended to prevent those with disabilities from straying into the vehicular way or an active construction area. Caution tape is not sufficient to guide those who are blind or low vision. Use only PCDs that are on the approved ODOT Qualified Products List, that are designed to be ADA compliant. Provide pedestrian channelizing devices:
9. Between the TPAR and any adjacent construction site.
10. Between the TPAR and the vehicular way, if the temporary pedestrian access route is diverted into the street.
11. Between the TPAR and any protruding objects, drop-offs, or other hazards to pedestrians.
12. At a curb ramp if the opposite curb ramp is temporarily and completely blocked, and no adjacent alternate circulation path is provided.
13. When work briefly or intermittently blocks or restricts the use of a pedestrian route, and a temporary detour route is not practicable due to the short duration of the restriction, provide a temporary means of allowing pedestrian access through or around the work area. Means of providing temporary pedestrian accessibility may include, but are not limited to temporarily suspending the work and making the pathway passable, or use of construction staff to guide pedestrians through or around the area.  When a TPAR is created in the public right-of-way, both visual and audible warning shall be provided at both ends of the temporary pedestrian access.
14. When direction signage or warnings are provided they should be located to minimize backtracking. Audible warnings shall be provided for those who are blind or low vision and should include specific directions allowing them to find the desired path.

290.4 Impacts to Traffic Signals

1. In no case may flagging operations take place in conflict with the indications of an operating traffic signal.
2. No flagging operations may take place within 200 feet of an operating traffic signal without a custom traffic control plan subject to a permit.
3. Should traffic control requirements dictate the "turn-off" and/or "turn-on" of a traffic signal, the applicant shall coordinate with the County Traffic Signal Shop at least two business days prior to turn-off and/or turn-on.

290.5 Temporary Road Closures

Temporary road closures are not for the purpose of convenience or cost reduction for an applicant.  Proposed closures shall establish that a clear public safety and convenience benefit would result from a closure.

1. The detour route shall be capable of safely and legally accommodating the detoured traffic.
2. With increasing ADT, functional classification and closure duration, the applicant's burden becomes greater in establishing the benefit of a proposed closure.
3. If a road closure is proposed, the following may be required:
4. Evidence that other methods of traffic control and/or that temporary improvements are not feasible in order to keep the road open. 
5. Time of day restrictions or extension of normal working hours and days.
6. Contract requirements of incentives/disincentives for completing/not completing closure on time.
7. A public engagement plan.
8. Off-site improvements to meet minimum safety of the detour route and/or to return the detour route to its original condition prior to the detour per Section 225.6.

280.1 Crosswalk Markings

1. Crosswalk markings shall be "continental" style (CW-SC per Oregon Standard Drawings TM 500 series) with two-foot wide bars and approximately three-foot wide gaps and be oriented in travel lanes to avoid vehicle wheel tracks. 
2. Crosswalks markings shall extend ten feet longitudinally. Curb ramps, when required, shall always be located within the longitudinal borders of the marked crosswalk.
3. Marked crosswalks shall be used at all signalized intersections. Marked crosswalks should be provided across all legs of a signalized intersection unless an engineering study establishes that a crosswalk would create a safety issue or significant operational issue at the intersection.
4. Marked crosswalks may be used in other locations as required by Engineering.
5. Marked crosswalks shall not be provided if there is not a curb ramp provided at ends of the marked crosswalk where it is necessary for pedestrians to cross a curb.

280.2 Left Turn and Right Turn Lanes Markings

1. Turn arrows shall be elongated per Oregon Standard Drawings TM500 series.
2. A minimum of two turn arrows shall be provided within each turn lane at both signalized and unsignalized turn lanes.
3. At signalized intersections, the first set of arrows should be placed a minimum of 40 feet from the crosswalk.
4. Dual turn lanes shall include dotted lane extension lines (WD per Oregon Standard Drawings TM500 series) through the intersection.

280.3 Stop Bars

1. Stop bars, if required, shall be placed behind the location of pedestrian crossings.
2. Stop bars should be used at all intersections with arterial, collector and connector roadways. 
3. Stop bars are not required if crosswalk markings are present except to address unique geometry or as directed by Engineering.

280.4 Transverse Marking Materials

Durable markings (Type B-HS) shall be used for all crosswalks, bike lane symbols, turn lane arrows, stop bars and other pavement legends unless installed for construction activities.

280.5 Longitudinal Markings

1. Durable markings should be used for all major and minor arterials within the urban area. 
2. Durable markings should be used for all lane extension lines and transition areas.
3. Durable markings should be used on all approaches within the queuing and transition areas approaching a signalized intersection or other areas where traffic would be expected to transition or frequently traverse over markings.  
4. High performance markings should be used for all other longitudinal markings.
5. Arterials and collectors should be marked with centerlines unless the requirements of the MUTCD don't call for centerlines. 
6. Arterials and collectors should be marked with edge lines except where the overall road width is less than 20 feet.
7. Paint, as defined by the Oregon Standard Specifications for Construction, may not be used on non-maintained local access roads unless temporary or as part of maintenance activities.

280.6 Reflective Pavement Markers (RPMs)

Centerline recessed reflective pavement markers (RPMs) should be used on the following roadways:

1. Arterial roadways.
2. Collector roadways outside the UGB.
3. Roadways where reflective pavement centerline markers already exist.

280.7 Temporary Markings

1. Foil-back tape of similar width to the permanent line may be used for temporary marking for a period not to exceed one month.  For periods exceeding one month, paint should be utilized.
2. Temporary reflective pavement markers (also known as "stick and stomps") may be used for a period not to exceed two weeks and should be checked frequently to ensure adequate delineation is present. 

280.8 Marking Materials

The materials to be used on the project shall be submitted to Engineering for review and approval prior to marking layout.

280.9 Marking Layout

The applicant should contact the County at least two business days in advance of striping for inspection of an applicant or contractor supplied striping field layout.

270.1 Design and Construction Requirements

1. All proposed signing and pavement markings shall comply with the requirements of the MUTCD, Oregon MUTCD supplement, the ODOT Sign Policy and Guidelines, Standard Highway Signs, the ODOT Qualified Products List, Oregon Standard Drawings, Oregon Standard Details, the ODOT Traffic Line Manual, ODOT Pavement Marking Design Guidelines, and Oregon Standard Specifications for Construction.
2. All plans shall be prepared under the direction of and stamped by an Engineer with expertise in traffic engineering. 

270.2 Street Name Signs

The design and construction of permanent street name signs shall conform to Standard Drawing T100.

270.3 End of Street

The end of streets shall be signed with:

1. Type OM4-2 object markers with a maximum spacing of six feet; or
2. Type III barricades per Standard Drawing T350. 

270.4 End of Sidewalk

The end of sidewalks shall be signed with at least one OM4-2 object marker.  For sidewalks wider than 8 feet, two OM4-2 object markers are required. Signs shall be mounted at approximate eye level (60").

270.5 Sign Mounting

The design and construction of permanent sign mounting shall conform to Standard Drawings T150 to T250.

1. The County has adopted a Clackamas County Local Streets Traffic Calming and Skinny Streets Program. 
2. The use of traffic calming measures shall be considered in cases where a development will have a detrimental effect upon existing residential local streets.  See Section 295 for additional information.
3. Traffic calming devices will only be considered if meeting the criteria of the Clackamas County Local Streets Traffic Calming and Skinny Streets Program or as recommended by Engineering to mitigate the impacts of a proposed development or project.

260.1 Traffic Signal Approval

A traffic signal may be approved if the criteria of this section are met. 

260.1.1 Traffic Analysis

A traffic analysis is required prior to the approval of a traffic signal.  Analysis requirements shall be based upon Section 295 and should include the following:

1. An analysis of other alternatives is required prior to the approval of a traffic signal.  Possible alternatives to traffic signal installation include right and left turn lane additions, other lane additions, alternative routes via planned or existing roadways, roundabout installation as well as modifications to traffic control. 
2. An analysis of capacity, queuing and safety both with and without the proposed traffic signal.  Additional roadway improvements may be required based upon this analysis to ensure safety is maintained with the installation of a traffic signal, notably left turn lanes. 
3. Unless the Comprehensive Plan specifically calls for a traffic signal, an analysis of alternatives shall establish that a roundabout is impractical or unreasonable before a traffic signal will be approved.  The analysis shall include preliminary geometry, a comparative estimate of right-of-way impacts of a traffic signal versus a roundabout, benefit/cost ratio, and a capacity analysis. 
4. Evidence that the criteria of Section 260.1.2 can be met. 
5. In locations with other traffic signals nearby, the proposed traffic signal shall not unacceptably decrease the corridor bandwidth.
6. A consideration of bicycle and pedestrian safety and mobility. 
7. An analysis of traffic signal phasing including:
8. Phasing analysis for different peak periods.
9. Evaluation of warrants for left turn protected, protected/permissive, and permissive/protected signal phasing, and protected right turn signal phasing based upon ODOT's Traffic Signal Policy and Guidelines.

260.1.2 Traffic Signal Warrants

1. New traffic signals at intersections on County roadways shall meet at least one, preferably several, of the traffic signal warrants of the current version of the MUTCD prior to the approval of a traffic signal.
2. Traffic signals meeting only peak hour volume warrants should only be approved if the intersection serves a special trip generator with unique peak traffic characteristics and evidence is provided that the traffic signal is a benefit to the public.

260.1.3 Traffic Signal Spacing

Traffic signals should be separated from existing or planned traffic signals a minimum of ¼ mile apart unless evidence supports adequate long term operations at a lesser spacing.  If an existing comprehensive plan illustrates spacing closer than this spacing, additional long term analysis is not required.   

260.2 Traffic Signal Design

1. Traffic signal design should be based upon the ODOT Traffic Signal Design Manual, Oregon Standard Drawings TM 400 and TM 600 Series, Clackamas County traffic signal drawings and details and the MUTCD.
2. Plans shall be consistent with the results of the traffic analysis performed under Section 260.1.1. 
3. Signalized intersections should be accompanied by channelized left turn lanes on the major street, on minor street arterials and collectors, and designed per Section 250.8.8.
4. Signalized intersections may be accompanied by channelized right turn lanes on the major street and minor street arterials and collectors as warranted by Section 295.19.1 and designed per Section 250.8.8.
5. Signalized intersections with pedestrian access routes shall comply with ADA requirements as described in the most recent version of ODOT's Traffic Signal Policy and Guidelines including accessible pedestrian signals and push buttons complying with the MUTCD, and meeting the provisions of PROWAG.
6. All plans shall be prepared under the direction of and stamped by an Engineer with expertise in traffic engineering.

260.3 Traffic Signal Materials

Materials used in the construction of traffic signals shall be approved by Engineering and comply with the Oregon Standard Specifications for Construction and the Clackamas County traffic signal drawings and details.

260.4 Material Submittals

Prior to signal construction, the materials to be used on the project shall be submitted to Engineering for review and approval in the form of standard Oregon traffic signal blue sheets, green sheets, red sheets and applicable cut sheets.

260.5 Traffic Signal Funding and Agreements

If approved in conjunction with a development, the following shall apply:

1. The applicant shall be required to enter into necessary agreements to fulfill the obligations of this section.
2. The applicant shall provide funds for necessary signal timing synchronization with existing traffic signals systems.
3. If approved at the intersection of a private driveway with a public roadway, the applicant shall be required to provide funds equal to 20 years of the maintenance and power of the traffic signal.
4. The applicant shall provide the necessary right-of-way and/or easements for County maintenance of the traffic signal appurtenances constructed at a development's private driveway or along a development's frontage.
5. The applicant shall maintain on-site pavement markings and signage in such a way that is consistent with the approved design.  Markings and signage shall be maintained in a way that is compliant with the MUTCD. 

260.6 Underground Communication Conduit

As required by Engineering, developments within the UGB shall be required to install fiber optic ready conduit under any of the following conditions:

1. When the development is required to install landscape strip and/or sidewalk along a collector or arterial roadway, the length of the work exceeds 200 feet, and is along a planned fiber optic network.
2. When the development abuts existing fiber optic conduit and extending the fiber optic conduit would extend a planned fiber optic network.
3. When the conditions of Section 260.7 apply.

260.7 Fiber Optic Communication

As required by Engineering, the installation of new traffic signals shall be accompanied by the installation of fiber optic conduit and fiber optic cable, unless existing, between the proposed traffic signal and adjacent traffic signals.

260.8 Flashers in School Zones

New schools or existing schools with an expansion of 20% floor area or greater shall be required to install school zone flashers on roadways that are classified as arterial or collector roadways if the proposed or existing school speed zone signing supports a school speed 20 MPH zone and the County supports a school speed zone installation.  In addition to school zone flashers, radar speed signs may be required along arterial roadways.

The applicant shall be required to provide funds equal to 20 years of the maintenance and power of the school zone flasher and/or radar speed sign. 

Roadway Standards Section 255 - Landscaping

Within the public right-of-way, landscaping and irrigation shall be maintained by adjacent the property owner unless an agreement exists that requires maintenance by others.  Street trees located within landscape strips are required by the ZDO as part of development.  The number of street trees along a property frontage shall be maintained by the property owner unless otherwise approved by the County.  Approved ground cover including shrubs, plants, or grasses should be installed at the time of development within landscape strips and landscaped medians.

If installed as part of development, landscaping and irrigation are subject to a Development Permit.  Otherwise, landscaping installation compliant with Section 130.2 is not subject to a permit.  Street trees that are removed are required to be replaced if required as part of land use approval. 

The County presents guidelines for street tree installation and landscaping not subject to a Development Permit.  It should be noted that regardless of compliance with County standards and guidelines for street tree planting, the adjacent property owner is responsible for the landscaping, and per ORS 368.910 and County Code Section 7.03, is responsible for the maintenance of adjacent sidewalk and curb and any damage that may be caused by landscaping or other activities.

255.1 Topsoil

The top 6" of topsoil in the planter strips shall be a well-draining soil blend suitable for growing.

255.2 Shrubs, Plants and Grasses

1. Shrubs, plants and grasses species should comply with the County's Shrub, Groundcover, Riparian Plant List. 
2. Landscaping should be designed to minimize water consumption and utilize Oregon native plants.
3. In addition to street trees, landscape strips should be planted with a sufficient quantity and density of shrubs, plants and grasses to minimize weed growth. 
4. Irrigation should be provided unless the applicant presents a planting plan that is likely to succeed as recommended by a Landscape Architect and/or Arborist. 

255.3 Street Trees

These standards are intended to ensure that new trees planted within the right-of-way are of the highest quality, require low maintenance, and will not compromise public safety.  Comply with the requirements of Standard Drawings L100 and L200.

255.3.1 Street Tree Selection

Street trees shall comply with the Clackamas County Street Tree List.

255.3.2 Street Tree Quality at Time of Planting

1. The trees shall have a straight trunk perpendicular to the ground with a minimum branching height of four feet above the ground for trees 1 ½" caliper to a minimum of six feet above the ground for trees with 2" caliper.  No trees may be planted with a caliper less than 1 ½" except as noted below.
2. Plant material shall be grown to the current standards and specifications of the American Association of Nurserymen and American Standard for Nursery Stock.  Plant material shall be of standard quality or better, true to name and type of their species or cultivar.
3. Trees shall be provided reasonably free, as defined by nursery industry standards for street trees, from insects, decay, major structural defects and damage to the trunk, branches, and root system.

255.3.3 Street Tree Condition at Time of Planting

1. If balled and burlapped in wire baskets:
2. Trees shall have a sound root ball with a firm attachment of the trunk with the root ball.  The trunk shall not be loose, but firmly held within the root ball.
3. The size and condition of root balls shall conform to the current standards and specifications of American Association of Nurserymen and the American Standard for Nursery Stock.
4. Root balls of trees shall not be allowed to dry out at any time from the nursery to the final planting.
5. Trees shall have a well-developed root system and not be root bound or have circling/girdling roots.
6. If in a container:
7. Trees shall be free of circling/girdling roots.
8. The trees shall have been grown in the container for a maximum period of one year.
9. If bare root:
10. Shall not exceed 1 ½" caliper, measured six feet above mean ground level.
11. The roots shall not be allowed to dry out and shall be kept moist at all times from the nursery to final planting.
12. The roots shall be well established and full of live and vigorous fibrous roots along with the larger structural roots.

255.3.4 Preparation of Tree Planting Holes

1. If balled and burlapped and in wire baskets:
   1. A shallow, broad tree planting hole at least 1 ½ times the diameter of the root ball shall be excavated to a depth that will position the trunk flare level with finish grade.
   2. The inner surfaces of the excavation shall be scored or roughened to the extent necessary to encourage rooting in the native soil.
2. If bare root:
3. Tree planting holes shall be one inch wider than the spread of the roots.
4. Holes shall have sufficient depth to position the trunk flare level with finish grade.
5. A mound of native soil shall be left in the center of the hole to support the roots.  The roots shall be draped and spread in their natural position over the mound.

255.3.5 Seating of Trees

1. Trees shall be set plumb, upright, and faced for best appearance.  Broken branches should be pruned after planting.
2. The hole shall be backfilled one-half with original soil and the hole flooded with water to remove any air pockets.  After backfilling is complete, the entire planting area shall be thoroughly saturated with water to remove any remaining air pockets.
3. Mulch shall be applied to a depth of two to four inches around the tree.  Mulch shall be kept free of an area within two inches of the trunk.
4. A continuous three inches high raised berm shall be constructed around the planting hole to direct water to the roots.  The berm should be removed after one year.

255.3.6 Staking

If an anchor system is not provided per Standard Drawing L200, staking is required:

1. Hardwood stakes shall be driven firmly into the ground outside of the hole.  Care shall be taken to avoid driving the stakes through the root structure.
2. Trees shall be attached to the stakes at a height of two feet using non-binding tree ties or tree ties that are at least one inch wide to prevent damage to the tree trunk.  Ties shall be attached in a manner that will allow the tree to move but still be held firmly in place.

255.3.7 Establishment Period

If installed as part of development, the establishment period for an original tree or replacement tree shall be determined by Section 190.4.

255.3.8 Root Barrier

Any tree planted ten feet or closer to a structure, such as curb or sidewalk, shall have an engineered impenetrable root barrier installed near the structure.  The root barrier shall run the length of the planting area or the structure and reach a depth of at least 18 inches.

255.4 Sight Distance

Proposed landscaping shall comply with the sight distance standards of Section 240.  If in question due to marginally adequate vertical or horizontal curvature, landscaping designers shall be required to provide evidence that proposed landscaping will not grow to become sight hazards.