scholarly journals Bedload transport in a steep alpine stream: Assessment of sediment mobility and virtual velocity using the bedload tracking

2018 ◽  
Vol 40 ◽  
pp. 02027
Author(s):  
Riccardo Rainato ◽  
Lorenzo Picco ◽  
Daniele Oss Cazzador ◽  
Luca Mao
Keyword(s):  
Field Studies ◽  
Bedload Transport ◽  
Monitoring Methods ◽  
Fluvial Systems ◽  
Passive Integrated Transponders ◽  
Average Recovery Rate ◽  
Sediment Mobility ◽  
Alpine Stream ◽  
Virtual Velocity ◽  
Term Field

The bedload transport is challenging to analyze in field, consequently, several assumptions about it were made basing on laboratory researches or on short-term field studies. During the last decades several monitoring methods were developed to assess the bedload transport in the fluvial systems. The aim of this work is to investigate the transport of the coarse sediment material in a steep alpine stream, using the bedload tracking. The Rio Cordon is a typical alpine channel, located in the northeast of Italy. It is characterized by a rough streambed with a prevalent boulder-cascade and step pool morphology. Since 2011, 250 clasts equipped with Passive Integrated Transponders (PIT) were installed in the main channel, to analyze their mobility along a reach 320 m long. From November 2012 to August 2015, the transport induced by a range of hydraulic forcing between 0.44 m3 s-1 and 2.10 m3 s-1 was assessed by 10 PIT-surveys. First, the mobility expressed by the tracers was analyzed, observing marked differences in terms of travel distance. Then, the average recovery rate achieved during the tracer inventories (Rr > 70%) permitted to define the threshold discharge for each grain size class analyzed and, then, to assess the virtual velocity experienced by the tracers.

Sediment mobility and bedload transport conditions in an alpine stream

2007 ◽  
Vol 21 (14) ◽  
pp. 1882-1891 ◽  
Author(s):  
Luca Mao ◽  
Mario Aristide Lenzi
Keyword(s):  
Bedload Transport ◽  
Sediment Mobility ◽  
Alpine Stream

Field Evaluation of Late Merge Traffic Control in Work Zones

2005 ◽  
Vol 1911 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Andrew G. Beacher ◽  
Michael D. Fontaine ◽  
Nicholas J. Garber
Keyword(s):  
Field Test ◽  
Traffic Control ◽  
Positive Response ◽  
Field Evaluation ◽  
Field Studies ◽  
Work Zone ◽  
Work Zones ◽  
Short Term ◽  
Term Field ◽  
Lane Closures

The traffic control strategy of the late merge in work zones was devised to improve flow and safety at work zone lane closures. Although some states have put the strategy into practice, only a handful of short-term field studies have formally evaluated its effectiveness. Additional field studies were necessary to assess the efficacy of the strategy and its proper deployment. This paper documents the results of a field test of the late merge traffic control conducted over several months. The late merge strategy was evaluated by comparing its effectiveness with that of traditional plans for work zone lane closures. The field test was conducted on a primary route in Tappahannock, Virginia, at a two-to-one lane closure. Results showed that throughput increased, but the increase was not statistically significant. Likewise, time in queue decreased, but the decrease was not statistically significant. These results were much less dramatic than those of other studies. Possible reasons for this disparity include different driver populations, road types, vehicle mixes, and site-specific characteristics. Despite limited improvements in throughput and time in queue, more drivers were in the closed lane, a positive response to the late merge signs.

Long-Term Field Aging of Warm-Mix and Hot-Mix Asphalt Binders

2017 ◽  
Vol 2632 (1) ◽  
pp. 140-149 ◽  
Author(s):  
Weiguang Zhang ◽  
Shihui Shen ◽  
Shenghua Wu ◽  
Louay N. Mohammad
Keyword(s):  
High Temperature ◽  
Prediction Model ◽  
Hot Mix Asphalt ◽  
Field Studies ◽  
Asphalt Binders ◽  
Climate Effect ◽  
Air Voids ◽  
Multiple Parameters ◽  
Term Field

Limited field studies have considered the aging of warm-mix asphalt (WMA) binders, especially from the perspective of long-term aging. This paper quantifies the long-term (10 to 82 months) field aging properties of WMA binders and the control hot-mix asphalt (HMA) binders and identifies the key factors associated with long-term field aging of asphalt. Asphalt binders from 23 field projects consisting of 65 HMA and WMA pavements were recovered, and high-temperature performance grade (PG) was tested. The effects of climate, month of aging, WMA technologies, and original binder high-temperature PG on field asphalt aging were analyzed. A prediction model that included multiple parameters was developed and validated. Results indicated that Evotherm WMA binder had a lower high-temperature PG than HMA binder shortly after construction, but this difference reduced with time. No statistical difference of field aging between HMA and WMA binders was observed. The climate effect on asphalt field aging was apparent within dry areas or freeze areas, whereas the aging difference between dry and freeze areas was inconclusive and requires further research. Other conclusions were that ( a) the field asphalt aging affects more of top-down longitudinal wheelpath crack than transverse crack, ( b) foaming WMA binder ages slowest of all binders considered, ( c) PG 64-XX and PG 70-XX binders aged more than PG 58-XX and PG 76-XX binders, and ( d) the prediction model had good agreement with test results and was well validated. The identified factors that affected field asphalt aging were overlay thickness, in-place air voids, effective binder content, complex shear modulus, and solar radiation.

Sign in / Sign up

Export Citation Format

Share Document