Quantifying the impact of new freeway segments.

Details

• Creators:
  McLellan, Jeffrey W.
• Corporate Creators:
  Arizona. Dept. of Transportation. Research Center
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Freeways
  • Travel time
  • Traffic congestion
  • Traffic volume
  • Benefit cost analysis
  • Evaluation
  • Arterial highways
  • Peak hour traffic
  • Traffic counts
  • Trip generation
• Publication/ Report Number:
  FHWA-AZ-13-613
• Resource Type:
  Tech Report
• Geographical Coverage:
  Arizona
• Corporate Publisher:
  Arizona. Dept. of Transportation. Research Center
• Abstract:
  Many freeway users complain that new freeway segments immediately fill up with traffic after they are constructed. This ; diminishes the advantages of reduced costs and reduced driving time that would make freeways theoretically superior to ; arterial streets. According to previous literature, however, this phenomenon is to be expected and is not an indicator of the ; efficiency or inefficiency of having new freeways. Due to Downs’s Law of Peak-hour Traffic Congestion, we expect freeways ; to immediately fill upon construction, simply because they do offer superior benefits to roadway users compared to the ; alternative arterial streets. Rational drivers choose to enjoy these benefits. Another phenomenon cited in the literature review ; is that of induced travel, which states that with the reduction in travel time posed by using freeway segments, it can also be ; expected that more commuters will choose to travel on them than otherwise would. ; When Downs’s Law works synergistically with the phenomenon of induced travel, more vehicles can be accommodated in a ; given geographical area, thus increasing the total number of trips taken. This adds to the overall value of our transportation ; system, since after all, the value of that system is predicated on its ability to facilitate increased volume of travel. ; This report is based on data acquired from the State of Arizona, the City of Phoenix and Maricopa County, Arizona, and other ; sources. Through our analysis of Maricopa County traffic count data we are able to show a significant increase in traffic ; volume resulting from adding new freeways. This increase in traffic volume accounts for a net benefit of over $18 million ; dollars per year for a given mile-long stretch of roadway. Over a freeway design-life of 20 years this is far in excess of the ; average of $72 million needed to construct that mile of freeway. ; Ultimately, any evaluation of the freeway system must take into consideration the explicit and implicit benefits of the system. ; We know that congestion is going to be present whether new freeways are constructed or not. Before freeway segments are ; constructed, the existing arterial streets are congested. After the completion of freeway segments, some drivers shift from ; arterial streets to the new freeway. This lessens traffic on the arterials, leading to more drivers taking trips they previously ; avoided (i.e. induced travel). Even though congestion is an inevitable condition, even on freeway segments postconstruction, freeways still offer a clear net benefit.
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• Format:
  PDF
• Funding:
  SPR-PL-1-(67) 613
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/26639/dot_26639_DS1.pdf
• File Type:
  [PDF - 2.39 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:9f34262afa9e145a3dbfbe236a8fef319aea92c64847d5dff55b9934e6ed173a