There are over four million miles of two-lane roadways across the United States, of which a substantial portion is low-volume roads (LVR). Traditionally, most traffic safety efforts and countermeasures focus on high-v...There are over four million miles of two-lane roadways across the United States, of which a substantial portion is low-volume roads (LVR). Traditionally, most traffic safety efforts and countermeasures focus on high-volume high-crash urban locations. This is because LVRs cover an extensive area, and the rarity of crashes makes it challenging to use crash data to monitor the safety performance of LVRs regularly. In addition, obtaining up-to-date roadway information, such as pavement or shoulder conditions of an extensive LVR network, can be exceptionally difficult. In recent times, crowdsourced hard-acceleration and braking event data have become commercially available, which can provide precise geolocation information and can be readily acquired from different vendors. The present paper examines the potential use of this data to identify opportunities to monitor the safety of LVRs. This research examined approximately 12 million hard-acceleration and hard-braking events over a 3-months period and 26,743 crashes, including 9373 fatal injuries over the past 5-year period. The study found a moderate correlation between hard acceleration/hard-braking events with historical crash events. This study conducted a hot spot analysis using hard-acceleration/hard-braking and crash datasets. Hotspot analysis detected spatial clusters of high-risk crash locations and detected 848 common high-risk sites. Finally, this paper proposes a combined ranking scheme that simultaneously considers historical crash events and hard-acceleration/hard-braking events. The research concludes by suggesting that agencies can potentially use the hard-acceleration and hard-braking event dataset along with the historical crash dataset to effectively supervise the safety performance of the vast network of LVRs more frequently.展开更多
A type of three-pitch fluctuating speed ratio limited-slip differential （TPLSD） is presented for the first time, analyzed its working principle, introduced the tooth profile design method of using non-involute tooth...A type of three-pitch fluctuating speed ratio limited-slip differential （TPLSD） is presented for the first time, analyzed its working principle, introduced the tooth profile design method of using non-involute tooth profile and separated tooth profile design along the pitch line. Performance comparison between vehicles equipped with three-pitch fluctuating speed ratio limited-slip differential and common open differefitial is finished. The data from experiments prove that three-pitch fluctuating speed ratio limited-slip differential can increase the traction of a vehicle, improve its acceleration performance, decrease braking distance and limit sideslip. The basic structure of new differential is the same of open differential, the only difference is that they have different tooth profile, so the new differential has a high performance price.展开更多
文摘There are over four million miles of two-lane roadways across the United States, of which a substantial portion is low-volume roads (LVR). Traditionally, most traffic safety efforts and countermeasures focus on high-volume high-crash urban locations. This is because LVRs cover an extensive area, and the rarity of crashes makes it challenging to use crash data to monitor the safety performance of LVRs regularly. In addition, obtaining up-to-date roadway information, such as pavement or shoulder conditions of an extensive LVR network, can be exceptionally difficult. In recent times, crowdsourced hard-acceleration and braking event data have become commercially available, which can provide precise geolocation information and can be readily acquired from different vendors. The present paper examines the potential use of this data to identify opportunities to monitor the safety of LVRs. This research examined approximately 12 million hard-acceleration and hard-braking events over a 3-months period and 26,743 crashes, including 9373 fatal injuries over the past 5-year period. The study found a moderate correlation between hard acceleration/hard-braking events with historical crash events. This study conducted a hot spot analysis using hard-acceleration/hard-braking and crash datasets. Hotspot analysis detected spatial clusters of high-risk crash locations and detected 848 common high-risk sites. Finally, this paper proposes a combined ranking scheme that simultaneously considers historical crash events and hard-acceleration/hard-braking events. The research concludes by suggesting that agencies can potentially use the hard-acceleration and hard-braking event dataset along with the historical crash dataset to effectively supervise the safety performance of the vast network of LVRs more frequently.
基金supported by Western-Area Transportation-Construction Scientific and Technological Project (No.200331822322)
文摘A type of three-pitch fluctuating speed ratio limited-slip differential （TPLSD） is presented for the first time, analyzed its working principle, introduced the tooth profile design method of using non-involute tooth profile and separated tooth profile design along the pitch line. Performance comparison between vehicles equipped with three-pitch fluctuating speed ratio limited-slip differential and common open differefitial is finished. The data from experiments prove that three-pitch fluctuating speed ratio limited-slip differential can increase the traction of a vehicle, improve its acceleration performance, decrease braking distance and limit sideslip. The basic structure of new differential is the same of open differential, the only difference is that they have different tooth profile, so the new differential has a high performance price.
