Investigation of Lane Flow Distribution on Hard Shoulder Running Freeways

Abstract

In response to an impending demand growth at an existing reactive managed lane system and to provide a timely and more effective temporary hard shoulder activation, this paper presents the development of short-term prediction models. A lane-oriented attribute—namely, the left-lane flow distribution ratio—is introduced to ameliorate the system by capturing the forthcoming stream dynamics and reconfiguring it to be proactive. To assess the impact on the network's performance of implementing a system for hard shoulder running, an exploratory analysis was performed on the basis of data acquired by seven radar sensors located every 500 m along a Swiss freeway section that was not affected by incoming or exiting traffic. A locally weighted regression was employed to provide more accurate insight into traffic behavior by comparing observations derived during the regular operation of the system and a period in which it was suspended, with respect to seasonality patterns. To describe the impending stream motion by examining different time–volume clusters (off-peak and peak hours), two prediction models were specified according to the time range. The preliminary results of the study for several prediction horizons demonstrate an acceptable prediction uncertainty. The hard shoulder activation prediction confirms the analysis of the findings of this research with regard to the impact on operations.

Safety Effects of Freeway Hard Shoulder Running

“…The aim of this study is to evaluate the safety effect of HSR by applying the EB (empirical Bayes) methodology to crash data from South Korea collected before and after the HSR trials. More The authors' review of the literature suggests that the international evidence on HSR is mixed [9][10][11][12][18][19][20][22][23][24]. More importantly, conflicting results and views have yet to be reconciled [19,20,24].…”

“…More The authors' review of the literature suggests that the international evidence on HSR is mixed [9][10][11][12][18][19][20][22][23][24]. More importantly, conflicting results and views have yet to be reconciled [19,20,24]. "Practicing traffic engineers generally believe that decreased congestion resulting from hard shoulder running is associated with some unspecified degree of improved safety; yet, the majority opinion among researchers is that accident rates increase with an increase in the number of lanes, even if full shoulders are provided.…”

“…The purpose of having a road shoulder is to serve as an emergency stopping lane for motorists and to allow for recovery of errant vehicles before a potential collision occurs [17]. Its omission may therefore result in more frequent vehicle crashes [18][19][20]. The Korea Expressway Corporation (KEC), the central authority for operating the freeway system, acknowledges that vehicle crashes in freeway sections with HSR have increased [21].…”

“…The increase in travel, whether for work or leisure, would contribute to the economy and improve the quality of life for users. [19,20,24]. "Practicing traffic engineers generally believe that decreased congestion resulting from hard shoulder running is associated with some unspecified degree of improved safety; yet, the majority opinion among researchers is that accident rates increase with an increase in the number of lanes, even if full shoulders are provided.…”

Application of locally weighted regression‐based approach in correcting erroneous individual vehicle speed data

“…Thereafter, applications of LWR techniques in the transportation field have expanded to include various topics such as: development of traffic prediction models [2][3][4]; assessment of traffic dynamics [5,6]; correction of missing vehicle trajectory data [7]; and algorithm design for an automatic no-passing zone locator [8].…”