Pilot Testing of SHRP 2 Reliability Data and Analytical Products: Washington (2014) / Chapter Skim
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Pages 40-58
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40 CHAPTER 4 Pilot Testing and Analysis on SHRP 2 L02 Product 4.1 Introduction The L02 project aims at developing tools and procedures for creating a system that monitors travel time reliability and quantifies the impact of varying conditions on the reliability. Ultimately, the L02 tools are intended to help transportation agencies answer five basic questions: 1.
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41 increasing as the roadway approaches the downtown Seattle exits and entrances. Because of the variable nature of operation times, the limited access nature of this facility, and the integration with traffic on mainline I-5, incorporating these express lanes into the travel time calculations would likely decrease the accuracy of the results.
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42 December 2012. Researchers chose to analyze data for weekdays Tuesday through Thursday.
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43 congestion level and a nonrecurring condition, the data could be plotted as a cumulative distribution function (CDF) chart, the key visual output of the L02 methodology.
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45 (d) Figure 4.2.
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46 Figure 4.3. Relative frequency of each regime on I-405 North.
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47 Figure 4.4. Relative contribution of each regime to travel delay on I-405 North.
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48 Figure 4.5. Average travel delay for each regime on I-405 North.
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49 Figure 4.6. Design and layout of I-405 Braided Ramps Project.
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50 Figure 4.7. Before-and-after TTI CDF for I-405 Braided Ramps Project under normal conditions.
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51 Figure 4.8. Before-and-after TTI CDF for I-405 Braided Ramps Project under incident conditions.
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52 Figure 4.9. TTI standard deviations for each regime before and after I-405 ramp project.
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53 The DRIVE Net system adopts the "thin client and fat server" architecture with three basic tiers to the web application: presentation tier, logic tier, and data tier (see Figure 4.10)
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54 Figure 4.10. DRIVE Net architecture (Wang et al.
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55 © OpenStreetMap contributors Figure 4.11. Routes available on the DRIVE Net platform for L02 reliability analysis.
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56 Using these new data, transportation agencies and roadway users can explore reliability anywhere along these implemented routes simply by inputting mileposts or clicking on the map. Travel time reliability information is available in two different forms: 1.
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57 © OpenStreetMap contributors Figure 4.13. Travel distance with varying levels of reliability.
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58 The distribution of travel times and how it is affected by recurrent congestion and nonrecurring events is clearly and efficiently shown by creating the CDF charts using the L02 methodology. Comparing performance targets to actual freeway performance is then easily accomplished, as long as targets are expressed in a way that is compatible with the L02 output.
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