Left-turning traffic without a protected left-turn signal is one of the major safety concerns at urban intersections. Though an average of only l0% - 15% of all approaching traffic turns left, significantly a large pr...Left-turning traffic without a protected left-turn signal is one of the major safety concerns at urban intersections. Though an average of only l0% - 15% of all approaching traffic turns left, significantly a large proportion of left-turn crashes occur involving 21% of all intersection fatal crashes. Where traditional safety countermeasures of signal timing-phasing and use of flashing yellow light have reportedly failed to significantly reduce the rate of crashes, an in-vehicle advance collision warning message can be helpful to reduce left-turn collisions at intersections. In this study, an in-vehicle audio warning application has been designed by providing two safety warning messages (Advance Warning Message and Safe Left-turn Maneuver Message) under the vehicle to vehicle (V2V) communication system, which is triggered based on the acceptable gaps of oncoming opposing vehicles for a safe left-turn. A driving simulator test has been conducted with 30 participants to investigate the impacts of warning messages on performance measures such as speed and acceleration profiles, collision records, brake reaction distance, and intersection clearance time. Statistical results showed that with the help of these messages, all participants were able to reduce speeds and accelerations and chose suitable gaps without potential conflicts. Moreover, the results of questionnaire analysis provide a positive acceptability especially for the Safe Left-turn Maneuver Message. Based on the performance measurements, this type of safety warning messages can be recommended for possible real-road tests for practical applications.展开更多
The easternmost Tian Shan lies in eastern Xinjiang, Central Asia. The South Barkol basin fault（SBF） in the northern part of the easternmost Tian Shan is a major tectonic structure in this orogenic region. The late Q...The easternmost Tian Shan lies in eastern Xinjiang, Central Asia. The South Barkol basin fault（SBF） in the northern part of the easternmost Tian Shan is a major tectonic structure in this orogenic region. The late Quaternary activity, paleoseismology, and deformation characteristics of the fault provide important clues for understanding the tectonic process of the eastern Tian Shan orogen and implementing seismic mitigation. Through interpretation of high-resolution satellite images, unmanned aerial vehicle measurements, and detailed geological and geomorphic investigations, we suggest that the fault exhibits clear left-lateral slip along its western segment. Paleoseismic trenches dug near Xiongkuer reveal evidence of six large paleoearthquakes. The four latest paleoearthquakes were dated： the oldest event occurred at 4663 BC–3839 BC. Data on the horizontal offsets along the probable 1842 Barkol earthquake coseismic rupture suggest clear multiple relationships between cumulative offsets and possible ~4 m of coseismic left-lateral slip per event. From the cumulative offsets and 14 C sample ages, we suggest an average Holocene left-lateral slip rate of 2.4–2.8 mm/a on the SBF, accounting for ~80% of lateral deformation within the entire eastern Tian Shan fault system. This result is comparable with the shortening rate of 2–4 mm/a in the whole eastern Tian Shan, indicating an equal role of strike-slip tectonics and compressional tectonics in this orogen, and that the SBF may accommodate substantial lateral tectonic deformation.展开更多
The ENE\|striking Altyn Tagh Fault (ATF) has been well known as a large, active left\|lateral strike\|slip fault that bounds the thrusting systems in NE Tibet.This fault has been the focal point in the debate between ...The ENE\|striking Altyn Tagh Fault (ATF) has been well known as a large, active left\|lateral strike\|slip fault that bounds the thrusting systems in NE Tibet.This fault has been the focal point in the debate between the discrete extrusion vs. distributed crustal shortening models. Although its active left\|lateralstrike\|slip features have been largely investigated and well documented by both satellite imagery and air\|photo interpretations and field observations, little study has been done upon its Cenozoic displacement history. Questions about the age of initiation and total offset accumulated on the fault remain controversial. A key area to resolve such question is located along the central segment of the fault in the Souerkuli and Mangar regions, where Neogene sedimentary basins well develop and are mostly distributed in three zones, namely from east to west: the Gobiling, Yitunbulak and Yusuale Tagh (Fig.1). Our field investigations were conducted along the ATF cutting the Yitunbulak and Gebiling Neogene sedimentary basins. Two stratigraphic unconformities observed within this Neogene conglomeratic series allow a separation of three major stratigraphic sequences and record the initiation and major deformational episodes of ATF during Cenozoic. An early stratigraphic unconformity occurred between a yellow depositional series below and early Pliocene red\|colored conglomeratic mudstones above. A later stratigraphic unconformities occurred between early and late Pliocene sedimentary series. The lower series below the early stratigraphic unconformities is mainly composed of a conglomeratic rocks containing cobbles and pebbles of basement rock units (mostly mylonitic granites, limestones and quartzes); this series has been poorly mapped and dated; its age could be assigned to late Oligocene to early Miocene; this series tilts to NW with an angle of about 30° and is overlain in angular unconformity by early Pliocene pebble\|sized conglomerates. A weathering zone on top of the lower conglomeratic series is clearly seen, that represents a long period of uplift and erosion. This lacuna occurred between early Miocene and early Pliocene in the west Qaidam basin, which has been documented only locally. Early Pliocene deposits correspond to alluvial to lacustrine facies rocks deposited in strike\|slip basin probably originated at releasing bend of the strike\|slip ATF; late Pliocene deposits is composed by fluviatile conglomerates and fanglomerates lying in unconformity on the upper Pliocene rocks. Early Quaternary deposits are absent along the ATF and have been well documented in the Qaidam basin. Late Quaternary fanglomerates infills active fault valleys.展开更多
文摘Left-turning traffic without a protected left-turn signal is one of the major safety concerns at urban intersections. Though an average of only l0% - 15% of all approaching traffic turns left, significantly a large proportion of left-turn crashes occur involving 21% of all intersection fatal crashes. Where traditional safety countermeasures of signal timing-phasing and use of flashing yellow light have reportedly failed to significantly reduce the rate of crashes, an in-vehicle advance collision warning message can be helpful to reduce left-turn collisions at intersections. In this study, an in-vehicle audio warning application has been designed by providing two safety warning messages (Advance Warning Message and Safe Left-turn Maneuver Message) under the vehicle to vehicle (V2V) communication system, which is triggered based on the acceptable gaps of oncoming opposing vehicles for a safe left-turn. A driving simulator test has been conducted with 30 participants to investigate the impacts of warning messages on performance measures such as speed and acceleration profiles, collision records, brake reaction distance, and intersection clearance time. Statistical results showed that with the help of these messages, all participants were able to reduce speeds and accelerations and chose suitable gaps without potential conflicts. Moreover, the results of questionnaire analysis provide a positive acceptability especially for the Safe Left-turn Maneuver Message. Based on the performance measurements, this type of safety warning messages can be recommended for possible real-road tests for practical applications.
基金funded by foundation of seismic risk assessment of active faults,China Earthquake Administration(Grant no.1521044025)
文摘The easternmost Tian Shan lies in eastern Xinjiang, Central Asia. The South Barkol basin fault（SBF） in the northern part of the easternmost Tian Shan is a major tectonic structure in this orogenic region. The late Quaternary activity, paleoseismology, and deformation characteristics of the fault provide important clues for understanding the tectonic process of the eastern Tian Shan orogen and implementing seismic mitigation. Through interpretation of high-resolution satellite images, unmanned aerial vehicle measurements, and detailed geological and geomorphic investigations, we suggest that the fault exhibits clear left-lateral slip along its western segment. Paleoseismic trenches dug near Xiongkuer reveal evidence of six large paleoearthquakes. The four latest paleoearthquakes were dated： the oldest event occurred at 4663 BC–3839 BC. Data on the horizontal offsets along the probable 1842 Barkol earthquake coseismic rupture suggest clear multiple relationships between cumulative offsets and possible ~4 m of coseismic left-lateral slip per event. From the cumulative offsets and 14 C sample ages, we suggest an average Holocene left-lateral slip rate of 2.4–2.8 mm/a on the SBF, accounting for ~80% of lateral deformation within the entire eastern Tian Shan fault system. This result is comparable with the shortening rate of 2–4 mm/a in the whole eastern Tian Shan, indicating an equal role of strike-slip tectonics and compressional tectonics in this orogen, and that the SBF may accommodate substantial lateral tectonic deformation.
文摘The ENE\|striking Altyn Tagh Fault (ATF) has been well known as a large, active left\|lateral strike\|slip fault that bounds the thrusting systems in NE Tibet.This fault has been the focal point in the debate between the discrete extrusion vs. distributed crustal shortening models. Although its active left\|lateralstrike\|slip features have been largely investigated and well documented by both satellite imagery and air\|photo interpretations and field observations, little study has been done upon its Cenozoic displacement history. Questions about the age of initiation and total offset accumulated on the fault remain controversial. A key area to resolve such question is located along the central segment of the fault in the Souerkuli and Mangar regions, where Neogene sedimentary basins well develop and are mostly distributed in three zones, namely from east to west: the Gobiling, Yitunbulak and Yusuale Tagh (Fig.1). Our field investigations were conducted along the ATF cutting the Yitunbulak and Gebiling Neogene sedimentary basins. Two stratigraphic unconformities observed within this Neogene conglomeratic series allow a separation of three major stratigraphic sequences and record the initiation and major deformational episodes of ATF during Cenozoic. An early stratigraphic unconformity occurred between a yellow depositional series below and early Pliocene red\|colored conglomeratic mudstones above. A later stratigraphic unconformities occurred between early and late Pliocene sedimentary series. The lower series below the early stratigraphic unconformities is mainly composed of a conglomeratic rocks containing cobbles and pebbles of basement rock units (mostly mylonitic granites, limestones and quartzes); this series has been poorly mapped and dated; its age could be assigned to late Oligocene to early Miocene; this series tilts to NW with an angle of about 30° and is overlain in angular unconformity by early Pliocene pebble\|sized conglomerates. A weathering zone on top of the lower conglomeratic series is clearly seen, that represents a long period of uplift and erosion. This lacuna occurred between early Miocene and early Pliocene in the west Qaidam basin, which has been documented only locally. Early Pliocene deposits correspond to alluvial to lacustrine facies rocks deposited in strike\|slip basin probably originated at releasing bend of the strike\|slip ATF; late Pliocene deposits is composed by fluviatile conglomerates and fanglomerates lying in unconformity on the upper Pliocene rocks. Early Quaternary deposits are absent along the ATF and have been well documented in the Qaidam basin. Late Quaternary fanglomerates infills active fault valleys.
