Roads/Highways

This report provides background on efforts to date of the U.S. Department of Transportation’s (USDOT) Integrated Corridor Management (ICM) System Program for the Interstate 15 corridor in San Diego County, one of eight sites selected to participate in the USDOT ICM program. The program’s goal is to counteract the effects of increasing congestion area on freeways, arterials and the public transit network. The report focuses on Stage II of the ICM project. Stage II work was scheduled for completion in Fall 2009, and was to be followed by Stage III, which includes implementation. The report...

In this report, the authors describe the Stage One work of the federally sponsored U.S. Department of Transportation’s (DOT) Integrated Corridor Management (ICM) Program for the I-15 Corridor in San Diego County, California, between State Route 52 in the city of San Diego and State Route 78 in the city of Escondido. The development work is based on the systems engineering process, meaning that the work focused specifically on the concept of operations and the system requirements specifications. The following elements comprise the development of the concept of operations: vision, goals and...

Freeway analysis procedures in the widely used Highway Capacity Manual (HCM) include the input of a driver population factor (Fp), which allows the analyst to adjust the demand depending on the familiarity of drivers with the roadway. This adjustment is based on the assumption that unfamiliar drivers will drive at slower speeds with longer headways and that higher capacity would therefore be required. However, little research supports the use of the Fp, and the HCM cautions against the use of Fp unless the analyst is fairly certain the traffic stream is actually unfamiliar with the roadway...

This paper shows through the evaluation of probe vehicle and loop detector data that travel time reliability on a freeway is NOT a function of counted traffic volumes until a “breakpoint volume” is reached. At that breakpoint the travel time reliability decreases (variance increases) abruptly. Once the breakpoint volume is exceeded, the decrease in travel time reliability is so extreme and abrupt as to suggest It is a vertical function, with a non-singular relationship to further volume increases. The breakpoint in reliability generally occurs at a counted volume significantly lower than...