Thomas Mulinazzi

Observed Distribution Patterns of On-Ramp Merge Lengths on Urban Freeways

Three on-ramp sites with moderate to high volumes of through and merge traffic along I-35 within the greater Kansas City, Kansas and Missouri, metropolitan area were selected for investigation of the distribution patterns of the merge lengths of ramp vehicles. On the basis of the observed merging behaviors, merge vehicles were categorized into three types: free merge (FM), challenged merge (CM), and platoon merge (PM). The field data were analyzed with specifically developed software. The results show that (a) FM vehicles merge onto a freeway at arbitrary locations, (b) CM vehicles require traveling a longer distance before a safe merge, and (c) PM vehicles follow a natural smooth path and force themselves onto the mainline traffic within a certain area of a merge lane. The 85th-percentile merge length of all ramp vehicles was further observed to be related to the CM volume, the PM volume, and the average speed of the freeway right-hand first lane. Finally, the potential applications of these findings were discussed, with an example illustrating how to use the 85th-percentile merge length to determine the minimum merge lane length for an urban freeway on-ramp.

Economic Impact of Closing Structurally Deficient or Functionally Obsolete Bridges on Very Low-Volume Roads

The state of Kansas has approximately 25,464 bridges located on state, county, and city roadway networks. As of May 2012 approximately 1,229 bridges on very low-volume roads were determined to be structurally deficient and candidate structures to be potentially closed, replaced, or repaired. This study was designed to provide such critical information for county commissioners or practicing engineers as (a) where structurally deficient or functionally obsolete bridges on low-volume roads were located, (b) what distance was the shortest drivable detour if these bridges were to be closed, and (c) whether to recommend closing or to repair or replace the structurally deficient bridges on the basis of both potential detour length and average daily traffic (ADT). The results of the study indicated that many of the structurally deficient bridges on very low-volume roadways had detours of 2 mi or less, were steel bridges, and had ADT values of fewer than eight vehicles. On the basis of the analysis, bridge closure was recommended for a low-volume roadway with an ADT value less than eight and a detour length of less than 9 mi.

An Evaluation Methodology for the Selection of an Interchange Configuration : Technical Paper

The evaluation methodology for selection of an interchange configuration which is presented in this paper is divided into four parts: 1) scrutinize the evaluation criteria to determine which ones are relevant; 2) estimate the initial cost of each reasonable alternative interchange design; 3) develop an Effectiveness Profile for each such alternative design; and 4) compare the initial cost and the Effectiveness Profile for each alternative design and then select an interchange configuration. The selection of pertinent evaluation criteria is fundamental to the evaluation methodology. The criteria chosen should measure differences between the alternative interchange designs. If no such criteria exist, then there is no difference between the alternative designs and the interchange configuration with the lowest initial cost should be selected. The initial cost was used as the cost indicator for each alternative interchange design. The initial cost was selected because it is easily obtainable and does not include some of the uncertainties associated with the calculation of road-user costs. The next step in the evaluation methodology is the development of an Effectiveness Profile for each alternative interchange design. An Effectiveness Profile is a graphical technique which shows each alternatives effectiveness rating for every evaluation criterion. It is based on the cost effectiveness approach of economic analysis and is the accumulation of several cost-effectiveness plots into a single graph. The final step in the evaluation methodology is to analyze the initial cost and the Effectiveness Profile for each alternative interchange configuration. This analysis will provide the decision maker with the necessary information to select an adequate interchange configuration for the given conditions.