Page 48 - TransportationPlanUsetsGuide

In the Portland metropolitan region, some roadways experience congestion that extends beyond the peak periods
of travel. Because off-peak travel conditions are not directly represented in the available peak-period travel demand
models, the Hours of Congestion Tool was developed to estimate the duration of congestion, especially for future condi-
tions where “peak spreading” is more likely to occur. Peak spreading refers to the situation where travelers shift their
trips from the peak period to the hours before or after the peak period (“peak shoulder hours”) in response to severe
congestion during the peak period. The Hours of Congestion Tool uses the peak-period travel demand models together
with estimated roadways capacities, and 24-hour traffic volume profile data to estimate the duration of congestion per
day for area roadways. Congestion is defined where hourly directional traffic volume is at least 90 percent of estimated
roadway capacity (i.e., level-of-service E or F). Locations in Washington County where future congestion may occur for
eight hours or more per day include:
• Boones Ferry Road (between Bridgeport Village and east of Tualatin Road),

• Tualatin-Sherwood Road,
• OR 217 (various segments between US 26 and I-5),
• OR 99W (through Tigard),

• Beaverton-Hillsdale Highway, intersection with Oleson Road and Scholls Ferry Road,
• Walker Road (various segments between Cedar Hills Boulevard and Amberglen Parkway), and
• TV Highway (between 170th Avenue and Cedar Hills Boulevard).

Maps illustrating existing conditions are included in the Existing Conditions and Future Needs Report in Chapter 2,
Figures 2-30 and 2-31.

Future Congestion
Future travel demand (year 2035 generated by using the Regional Travel Demand Model) was assigned to the future
County transportation network (includes facilities currently in place and improvements currently funded through MSTIP
3d and other funding sources likely to be in place by 2035). Many of the roadways in Washington County will not meet
the Washington County LOS standards without some form of improvement to the roadway system. Three categories of
system improvements will be needed in the future:
• Roadways in the vicinity of the urban reserves will need to be improved to accommodate travel demand
created by development anticipated in the urban reserve areas, unless a complete urban network is as-
sumed to be provided within the urban reserve areas. Since this network only includes projects with com-
mitted funding, such improvements were not included in this analysis, but can be expected in the future.

• Implementation of transportation improvements in conjunction with development along arterial and col-
lector roadways that are not currently completed to urban standards. In many locations roadway improve-
ments have been deferred until development occurs on the adjacent properties. It is assumed that such
development will likely be conditioned to complete the roadway to urban standards along the frontage.
• It is expected that additional funding will be available between now and 2035 for transportation system
improvements that are not included in this network. This network does not utilize that funding; thus it rep-
resents a “conservative” view of future transportation system needs.

The analysis of future transportation system needs was repeated, using a transportation system network that included
additional improvements included in the RTP “State” list of transportation projects. Implementation of the “State” 2014
RTP projects achieves significant improvement in roadway performance compared to the “Committed” system, and the
expected operation of most facilities is drastically improved. More detailed information, along with graphic illustrations
of the results of this analysis, is included in Chapter 2 of the Existing Conditions and Future Needs Report.

38 PART 3: TRANSPORTATION MODAL ELEMENTS
Effective November 27, 2015 • Updated December, 15 2016