We studied the way people use Thompson Road to find which improvements are needed. We looked at existing and expected (year 2043) traffic volume, as well as the needs of cyclists and pedestrians.
Traffic signals
Seven intersections are in the project area between (but not including) Saltzman Road and Permian Drive. None of the intersections have traffic signals. We do not expect any intersection to meet the requirements for a traffic signal under expected year 2043 traffic conditions.
Pedestrian and Bike Facilities
No streets in the study area have pedestrian or bicycle classifications. We performed a pedestrian count. Few pedestrians were seen crossing the street. Thompson Road does not meet the County’s criteria for marked crosswalks or controlled crossings. There are bike lanes on NW Thompson Road west of NW 128th Avenue. Otherwise, cyclists use the existing travel lanes, sharing the road with vehicles. Bike facilities will be installed with the Thompson Road Project.
Crash Data
ODOT data shows no crashes involving pedestrians or cyclists in the corridor. There was no more than one crash reported over the five-year period (2016-2020) at any of the intersections. There are no crash trends to inform the design of NW Thompson Road. Continuous sidewalks and bike lanes and a center left-turn lane will improve comfort, convenience, and safety for all travelers.
Future No-Build Traffic Operations
We examined expected traffic conditions in the year 2043 with the existing road design. The study shows that intersection operations would meet the County’s performance standards.
Future Build Scenario Traffic Operations
We analyzed traffic conditions in the year 2043 under the planned improvements. Traffic volumes along the NW Thompson Road corridor are expected to increase by about 50 percent between now and the year 2043. The study shows the planned three-lane cross-section will serve the future needs of the County.
Queuing Analysis
No more than one vehicle is expected to queue in the left-turn lanes on NW Thompson Road during future peak hours. Left-turn lanes are designed using the County-standard turn pocket length of 100 feet.
Intersection Sight Distance
We evaluated sight distance at NW Thompson Road & NW Hibbard Drive by County guidelines. We plan to move existing utility cabinets at the northwest corner due to conflicts with the proposed sidewalk. We are also looking at ways to keep the existing utility pole, fence, and hedges in the northeast corner.
The private development planned on the south side of Thompson Road, west of Hibbard Drive, prevents us from realigning the road to straighten the existing curve.
The existing curve supports a design speed of between 30 and 35 mph. 85% of people travel 41 mph (eastbound) and 44 mph (westbound), or less. The road is classified as an arterial, with a design speed of 45 mph.
Since the curve of the road is less than the design speed, we will need to request a design exception. The design exception will consider other safety considerations, including:
Crash history
ODOT data indicates no crash trends to inform the design of NW Thompson Road.
Sight distance
Building bike lanes next to the travel lanes will provide more clear sight distance through the curve.
Signage
We will keep the chevrons and advance warning signs posting a speed of 30 mph through the curves.
Street lights
Lighting upgrades will improve safety.
We may also look at reducing the superelevation (tilt of the road) through the curves. The superelevation is more than 6%, which is great enough for a stopped vehicle to slide when there is ice on the road. Reducing the superelevation to 4% to 6% can mitigate this concern.
