Ultimate Capacity
Roads Proposed for Ultimate Capacity
Airport Road / 128th Street SW
SCC 30.66B.110 provides that “when the county council determines that excessive expenditure of public funds is not warranted for the purpose of making further improvements on certain arterial units, the county council may designate, by motion, following a public hearing, such arterial unit as being at ultimate capacity”.
SCC 30.66B.110(1)(a) provides that “designation of ultimate capacity shall include a commitment by the county to complete an access management and circulation plan for the arterial unit and a commitment by the county for specific, additional road improvements, transportation system management (TSM) actions, access management improvements, and/or transportation demand management (TDM) actions for the purpose of improving efficiency, preserving roadway capacity, and improving operations. In addition, any known improvements needed to address safety issues must be identified in conjunction with such ultimate capacity designation.”
“Ultimate Capacity” is a growth management tool that attempts to provide an answer to the following question: How do communities facilitate enough high-density development to support transit without triggering concurrency restrictions on development? Snohomish County has adopted rules and regulations that essentially allow a lower level of service on roads designated as ultimate capacity.
One of the main objectives of GMA is to create more compact, viable, livable urban areas utilizing increased densities, especially within urban centers. This creates challenges for the transportation systems because increased densities create increased traffic congestion. Concurrency is the GMA tool that places a limit on the amount of congestion that communities will tolerate in certain areas before stopping further development. The long-term ‘solution’ to the traffic congestion in the most urbanized areas is good local transit service which is only ‘economically viable’ when high density residential and commercial development are in place. Thus there is a challenge. How do communities facilitate high-density development, to the point where transit becomes viable, without triggering concurrency restrictions on development? The following table shows the GMA objectives addressed by Snohomish County’s rules and regulations for ultimate capacity.
| GMA Objective in RCW 36.70A.020 |
How the use of ultimate capacity relates to the GMA objective |
| (1) Urban growth. Encourage development in urban areas where adequate public facilities and services exist or can be provided in an efficient manner. |
Designation of certain arterial as ultimate capacity will enable increased density of both residential and commercial development in the surrounding (and immediate) areas served by the arterial to increase the viability of more efficient modes of transportation including transit, vanpools and carpools. |
| (2) Reduce sprawl. Reduce the inappropriate conversion of undeveloped land into sprawling, low-density development. |
Snohomish County’s adopted GMA Comprehensive Plan identifies the areas suitable for higher density urban development. Without designations of ultimate capacity on arterials in these areas (once they have been improved to a certain level), concurrency restrictions can prevent the increased densities of development necessary to fully achieve these higher densities, forcing growth into lower density areas or even outside the urban growth area. |
| (3) Transportation. Encourage efficient multimodal transportation systems that are based on regional priorities and coordinated with county and city comprehensive plans. |
Efficient multi-modal systems depend upon high density residential and commercial development. Ultimate capacity is a tool to help achieve that density. |
| (7) Permits. Applications for both state and local government permits should be processed in a timely and fair manner to ensure predictability. |
Determination of ultimate capacity streamlines concurrency determinations for developments impacting such arterials. |
| (12) Public facilities and services. Ensure that those public facilities and services necessary to support development shall be adequate to serve the development at the time the development is available for occupancy and use without decreasing current service levels below locally established minimum standards. |
All developments impacting arterials designated as ultimate capacity would still be subject to concurrency, but the determination of ultimate capacity would effectively establish a lower level of service standard and shift the focus to multimodal transportation. Development impacting ultimate capacity facilities are required to meet new Transportation System Management (TSM) requirements (e.g. access control) and either meet revised (more intensive) Transportation Demand Management (TDM) requirements, or meet criteria for transit compatibility. Determinations of ultimate capacity also include commitments to additional road improvements, TSM actions, and/or TDM actions by the County. Examples might include access control, periodic signal coordination, signal upgrades, and support for corridor-level employer commute trip reduction programs. |
Level of Service Standards
- The minimum level-of-service standards for county arterials are established in the transportation element of the county comprehensive plan and are set forth in SCC 30.66B.101 and SCC 30.66B.102 (see below). The determination of whether or not an arterial unit meets the adopted level-of-service standards is as follows:
- First, if the average daily trips (ADT) on an arterial does not exceed the threshold identified in SCC 30.66B.101, the arterial unit meets the county s standard.
- As shown below in italic font, once a road is designated as ultimate capacity a higher ADT threshold is established.
- For roads not designated as ultimate capacity the ADT thresholds are low, and only arterials with relatively low volumes will meet the standard.
- For roads designated as ultimate capacity the thresholds are high, and are intended to be difficult, but not impossible, to exceed.
30.66B.101: Transportation Level of Service Standard: Average Daily Trip (ADT) Thresholds
|
Thresholds Measured as Number of Average Daily Trips (ADT) |
Road Not Designated as Ultimate Capacity
|
-
Road Designated as Ultimate Capacity
-
|
Number
of
Lanes |
Rural Arterial Unit |
Urban Arterial Unit |
Rural
Arterial Unit |
Urban
Arterial Unit |
| 2 |
4,000 |
7,000 |
18,000 |
22,000 |
| 3 |
5,000 |
9,000 |
27,000 |
33,000 |
| 4 |
7,000 |
12,000 |
36,000 |
44,000 |
| 5 |
n/a |
15,000 |
45,000 |
55,000 |
| 6 |
n/a |
16,000 |
54,000 |
66,000 |
| 7 |
n/a |
21,000 |
63,000 |
77,000 |
- If the ADT on an arterial unit exceeds the threshold identified in SCC 30.66B.101, the average travel speed is evaluated. If the average travel speed on the arterial unit falls below the appropriate threshold identified in SCC 30.66B.102, then the level of service on the arterial unit does not meet the county s standard.
- It is expected that for roads designated as ultimate capacity, once the ADT thresholds are exceeded, they will almost certainly fail the average travel speed test.
30.66B.102: Transportation Level-of Service Standards: Average Travel Speed
| Rural / Urban Arterial Unit Classification |
Transit Compatibility(1) and Qualifying Public Services(2) |
Average Travel Speed Standard |
| Rural |
No |
C(3) |
| Yes |
D(3) |
| Urban |
No |
E(4) |
| Yes |
Five (5) miles per hour less than E(5) |
Ultimate Capacity Provisions of Ordinance 05-092
The 2005 amendments to Chapter 30.66B SCC adopted criteria that Public Works uses to make recommendations to the county council for whether or not certain arterials should be designated as “ultimate capacity.”
Initiated by a recommendation from the Public Works Director,
- upon completion of an engineer’s report, and
- based on criteria in code and DPW rules.
Ultimate capacity is a County Council determination,
- by motion following a public hearing,
- when excessive expenditure of public funds would not be warranted for making further improvements.
- When arterial is designated ultimate capacity, a different LOS standard would apply, which would effectively allow much reduced travel speeds.
Criteria for DPW Recommendation and Council Designation
- Either road is totally improved consistent with long-range plan, or
- road is partially improved but certain constraints preclude additional cost effective improvements.
If road is only partially improved, then
- number of general-purpose travel lanes (excluding turn lanes) is consistent with the adopted transportation element,
- adequate provisions are made to accommodate pedestrian and bicycle demand, and
- If the source of delay is another agency’s facility, then the approach to that facility is totally improved consistent with long-range plan.
Developments impacting ultimate-capacity arterials would be required to:
- provide access management and circulation provisions, and either
- provide transportation demand management (TDM),
- or meet the criteria for transit compatibility.
Designation by Council to include a commitment by the County to
- complete any known improvements needed to address safety issues,
- complete an access management and circulation plan, and
- transportation system management (TSM) actions, access management improvements, and/or transportation demand management (TDM) actions for the purpose of improving efficiency, preserving roadway capacity, and improving operations.
“TSM” is the acronym for “transportation systems management” and includes the “high tech” signal timing, coordination, and monitoring that we have in these corridors and continue to improve.
Access Management can increase roadway capacity by 20 to 40 percent through limiting vehicle conflicts at driveways and other points of access. Access Management may include both land-use actions (e.g., requirements for shared driveways and parking) and minor capital improvements (e.g., center curbing).
“TDM” is the acronym for “transportation demand management. TDM responds to the long-term need to maintain mobility while reducing vehicle trips and includes programs that provide incentives for sharing rides and using transit (e.g., “developer TDM” and “commute trip reduction”).
- 1990-1995. Origins of Concept of Ultimate Capacity. Concept dates to 1990 amendments to Title 26B, 1992 Countywide Planning Policies, 1995 GPP and Transportation Element, and 1995 amendments to Title 26B.
- 1996. The 1996 GMHB “Sky Valley” decision stated that “a development is subject to concurrency requirements even in the case where the service or facility affected by the development is found to be at its ultimate capacity.” The County rewrote TR 5.A.1 as a result of Sky Valley.
- 1997. Sno-Wood Road Designation. Sno-Wood Road was designated as Ultimate Capacity by Council in 1997. Motion of adoption called for “operational improvements.”
- 2005. Ordinance 05-092 County Council adopted revisions to Chapter 30.66B SCC establishing LOS standards for arterials designated as ultimate capacity. This ordinance also established a process and criteria for ultimate capacity designations.
- 2006. Public Works adopted Rule 4224.100 providing details and specificity related to the process and criteria for ultimate capacity designations.
- 2007. 164th ST SE/SW Designation. 164th ST SE/SW (Arterial Units #218 and #219) was designated as Ultimate Capacity by County in December 2007.
- 2009. Amended Ordinance 09-004. The County Council adopted revisions to SCC 30.66B.101 (effective March 27, 2009) amending the LOS standards for both arterial units not designated as ultimate capacity and arterial units designated as ultimate capacity.
The County currently has two arterial units at ultimate capacity, Snohomish-Woodinville Road in TSA E and 164th ST SE/SW in TSA D.
164th ST SW/SE (Arterial Units #218 and #219)
On December 17, 2007 the County Council unanimously adopted Amended Motion 07-123 designating 164th ST SW/SE (Arterial Units #218 and #219) as ultimate capacity. To maintain mobility and preserve capacity in this corrior, Snohomish County Public Works will implement a congestion management strategy including transportation systems management (TSM), transportation demand management (TDM) and access management. This site will be updated as that strategy is further developed and implemented.
Snohomish County Council Motion No. 97- 202 designated Snohomish-Woodinville Road as being at “ultimate capacity” effective June 23, 1997. The motion laid out in detail why this action was taken and what it means for developers and the County. In the motion the Council directed DPW to improve Snohomish-Woodinville Road’s operating efficiency (e.g., shoulders and/or center turn lane). In March 2000 a pre-design study to evaluate design alternatives was completed. The study confirmed that the lack of width between the railroad tracks and SR 522 at the County Line precludes the possibility of constructing additional general-purpose lanes. The final improvements on Sno-Wood Road were completed in 2005. The improvements include two travel lanes, a center turn lane, bicycle lanes in both directions, a planter strip, curb, and sidewalk on the west side, stormwater detention ponds, and a traffic signal at the intersection with 240th St SE. As the road approaches the SR 522 off-ramp, it widens to five lanes. This configuration matches the WSDOT proposed improvement on SR 522. The improvements were coordinated with the City of Woodinville at the south end of the project and the development of a large COSTCO store at the intersection with 240th ST SE. COSTCO constructed some of the improvements as offsets to their traffic mitigation fees.