A Focused Approach
In 2009 the Oregon Department of Transportation started a new approach to deal with recurring localized freeway bottlenecks in the Portland Metro area. According to a recent FHWA study approximately 40 percent of all congestion nationwide can be attributed to recurring congestion.
This approach is to better scale freeway improvements to effectively reduce recurring bottlenecks within a constrained revenue forecast.
Region 1 has now completed the Corridor Bottleneck Operations Study (CBOS) to identify major congestion bottlenecks on freeways and develop cost effective, small-scale operational improvements to address freeway safety and operations. This study is in response to Federal Highway Administration (FHWA) Localized Bottleneck Reduction (LBR) program which focuses on relieving recurring bottlenecks and the operational influences that cause them.
Safety and Operations
The primary purpose is to improve safety and operations at these recurring bottleneck locations. The projects recommended are not capacity improvements; they are designed to relieve localized congestion caused by the recurring bottleneck and reduce the number of collisions on the freeway.
The Corridor Bottleneck Operations Study (CBOS) Project Atlas identifies recurring bottleneck locations along the five metro area corridors (I-5
and US 26
) and identifies recommended projects for those locations.
The development of the Project Atlas consists of three steps:
• Corridor-level reconnaissance:
ODOT conducted a corridor-level reconnaissance to identify and validate specific bottleneck activity and causes.
• Bottleneck analysis, evaluation, screening, and selection of solutions:
Bottlenecks were analyzed and potential solutions were developed, evaluated, and screened by an expert multidisciplinary design panel.
• Refinement of solutions:
The final step involved a more thorough operations and design evaluation of potential solutions deemed feasible by the screening panel. The detailed evaluation and refinement included traffic modeling evaluation of various performance measures and assessment of project feasibility as related to project cost, impacts and benefits.
Projects were selected as providing the best value of benefits and cost (primarily <$1 million to $20 million range). It should be noted, however, that traffic volumes on these highways are very high, particularly during the peak commute hours, and because these operational improvements do not add capacity, the benefits achieved will likely be moderate and incremental.
The intent of the proposed projects are to reduce congestion at identified recurring bottlenecks, particularly on the peak commute shoulders, and enhance safety by reducing the weave and merge problems that occur at interchanges.
View the Project Atlas
(note: this is a very large file; it may take several minutes to load)
Previous Low-Cost Projects
Three previously constructed safety and operational projects served as models for the development of CBOS. They were low-cost safety and operations improvements that were implemented very quickly, had low environmental and ROW issues and impacts, and were highly visible and popular with the public. The positive impacts of these projects on improving the location bottleneck for safety and operations are dramatic:
• Addition of an Auxiliary Lane:
Two recent auxiliary lanes were built on I-5 south and northbound between I-205 and Elligsen Rd interchanges. These two auxiliary lanes provide significant congestion relief to the high volume I-5 to I-205 freeway to freeway connection.
o I-5 southbound auxiliary lane was built in 2009-10 as part of a 6.5-mile pavement preservation project on I-5.The 1.5-mile auxiliary lane, between the I-205 southbound entrance ramp and Elligsen Road exit-ramp cost was approximately $5 million. This section of I-5 was ranked 125th on the national freight congestion list. The auxiliary lane allows for improved weaving for I-205 south to I-5 south traffic, because of the short distance between I-205 and Elligsen Rd. interchange.
o I-5 northbound auxiliary lane was built in 2011. This auxiliary lane provides substantial operational improvements at the Elligsen Rd loop entrance ramp to I-5 northbound and the I-5 northbound to I-205 northbound ramp. This auxiliary lane improves this weaving section for the high truck travel between Elligsen Rd and I-205. The project covered a 2-mile section of I-5 and costs approximately $6.5 million.
• Entrance Ramp Improvement:
I-5 Southbound exit-ramp to Nyberg Road
Due to the high Nyberg Road exit-ramp volume in the peak afternoon commuter time, congestion at the ramp often backed traffic onto the freeway. This has resulted in a high number of rear-end crashes and was a top 10% SPIS site.
In 2010 the I-5 southbound exit-ramp to Nyberg Road was improved. This improvement was done as part of the I-5 pavement preservation project in 2009-2010.
The improvement widened the southbound Nyberg Road exit-ramp from one lane to two lanes, with the inside lane operating as an option lane for I-5 southbound traffic to either exit to Nyberg Road or continue through on I-5 South. The ramp widening resulted in significant crash reduction and operational improvement. The construction cost was approximately $500,000.
For more information, contact
Tim Wilson, ODOT Major Projects
Rian Windsheimer, ODOT Planning and Development Manager