Reduction In Average Speed Research Articles

COMMUNITY PREVENTION STRATEGIES FOR SPEED REDUCTION IN SCHOOL ZONES: WHAT ARE THE REAL IMPACTS?

BACKGROUND: Pedestrian injuries are responsible for most transport related fatalities among children, emphasizing the importance of implementing good practices to improve child pedestrian safety. Pedestrian fatality risk is directly related to speed. Accidents involving a car traveling more than 40 km/h have drastically a higher risk of death. The city of Sherbrooke and various stakeholders build up community-wide strategies based upon engineering, enforcement, advocacy and education to reduce vehicle speed in school zones to improve pedestrian safety, reduce injuries severity and promote active transport. OBJECTIVES: To compare the average vehicle speeds in school zones between school hours (7am-5pm, Monday to Friday) and the rest of the week (evenings, nights and weekend). DESIGN/METHODS: A cross-sectional study to measure vehicle speeds was performed during 26 complete days, in October and November 2015 after implementing community prevention strategies around 4 elementary school zones in the city of Sherbrooke. Vehicle speed measurements before the intervention were available for one school zone and used for a before-after analysis. RESULTS: A total of 130, 274 vehicle speeds were measured in fall 2015. The mean speed for all school zones was 36.9 ± 5.4 km/h between 7am-5pm compared to 42.7 ± 5.8 km/h for evening, night and weekend hours (p < 0.0001). Furthermore, we observed an 9% reduction of vehicle speed on 7am-5pm weekdays after the implementation of prevention strategies in 2015. The mean speed was 36.4 km/h in 2013 and 33.2 km/h in 2015. CONCLUSION: Community-based interventions are an efficient method to reduce speed during school hours. These strategies led to a reduction in average speed during other hours of the day and during the weekend. However, the average speed measured in school zones were not under 30 km/h between 7am-5pm. These strategies could help other cities to promote safe pedestrian environments and improve active transportation and physical activity among children.

Emission of pollution from motor vehicles with respect to selected solutions of roundabout intersections

The article concerns the assessment of emmision of selected two-lane roundabout functioning in the city of Rzeszow and its alternate turbo version. In the work was considered four scenarios that represent two different in terms of traffic congestion time of day. The results of the emission of selected components of the exhaust gas (NOx and particulates PM10) were obtained on the basis of calculations of emission model VERSIT+ Enviver. While the input data for the calculations were taken from the modeled options of roundabouts in the Vissim program. The results from the Enviver program were compared to calculations from mesoscopic model COPERT 5. The results show that the overall reduction in average speed, as well as increased frequency of braking and sudden acceleration, directly contribute to the growth of harmful emissions. However, with respect to comparision of turbo roundabout in regard of currently running two-lane roundabout can be observed reduction of selected components of exhaust gases emission about approx. 1/3.

Effect of Using an In-Vehicle Smart Driving Aid on Real-World Driver Performance

A smart driving system (providing both safety and fuel-efficient driving advice in real time in the vehicle) was evaluated in real-world on-road driving trials to see if any measurable beneficial changes in driving performance would be observed. Forty participants drove an instrumented vehicle over a 50-min mixed-route driving scenario. Two conditions were adopted: one is a control with no smart driving feedback offered and the other is with advice being presented to the driver via a smartphone in the vehicle. Key findings from the study showed a 4.1% improvement in fuel efficiency when using the smart driving aid, importantly with no increase in journey time or reduction in average speed. Primarily, these efficiency savings were enabled by limiting the use of lower gears (facilitated by planning ahead to avoid unnecessary stops) and an increase in the use of the fifth gear (as advised by the in-vehicle system). Significant and important changes in driving safety behaviors were also observed, with an increase in mean headway to 2.3 s and an almost threefold reduction in time spent traveling closer than 1.5 s to the vehicle in front. This paper has shown that an in-vehicle smart driving system specifically developed and designed with the drivers' information requirements in mind can lead to significant improvements in driving behaviors in the real world on real roads with real users.

Average-Speed Forecast and Adjustment via VANETs

A wet road is slippery so vehicles often slow down their speed to increase the safety margin, thus usually reducing the average speed. This reduction in average speed may produce a chain reaction that shifts, extends, or amplifies a slowdown on downstream road segments. Conventional average-speed forecasting approaches are unable to respond to sudden chain reactions because these approaches do not consider the effect of weather factors and upstream road segments. Since accurate forecast of average speed can improve gas consumption, carbon dioxide emissions, and travel time, this paper proposes a short-term average-speed forecast and adjustment (ASFA) approach based on a study of prediction bias correlation among adjacent road segments and on weather factors, such as temperature, humidity, and rainfall. First, this approach applies an artificial neural network to predict the average speed of a road segment. Then, vehicles can monitor current traffic to calculate average speed via vehicular ad hoc networks (VANETs). Finally, the vehicles adjust the predicted average speed according to the observed average speed. Real traffic measurements and weather data are used for the evaluation of the proposed scheme and Civic Boulevard in Taipei City is selected as the prediction target. The results show that the proposed ASFA improves accuracy by 57.4% when compared with a hybrid approach on an urban street during rush hour. This paper estimates and simulates a case study by aggregating traffic data in 186 ms on Shi-Min Boulevard via the VANETs during rush hour.

고속도로 노면표시 감속유도시설 효과평가

PURPOSES: Since expressways in South Korea are toll roads, many trumpet type interchanges exist, resulting in the installation of loop ramps very frequently. While the travel speed of the main lane is designed to be 100-110 km/h, the structure of a loop ramp is different and is designed for a minimum speed of 40 km/h. In fact, most of the actual travel speeds measured on the ramp exceed the designated speed, which has been a major problem in traffic safety. In this research, a type of pavement marking speed-reduction treatment called the “Peripheral Transverse Line”is installed on expressway loop ramps in order to study the change of driving speeds after the installation. METHODS: To verify statistically the change, this speed-reduction treatment has been installed on the Chungju interchange and the Yeoju junction. The driving speeds before the installation were compared with driving speeds both one month and five monthsafter the installation. RESULTS: As a result, the reductions of the average driving speeds after the treatment were statistically significant. More specifically, the average driving speeds of the Chungju interchange were reduced by 7.1-7.7 % for its tangent road section, and the speeds decreased by 8.5-9.5 % for its curve section. Similarly, in the Yeoju junction, an average speed reduction of 2.9-4.8 % for its tangent section was measured, along with 3.9% long-term speed reduction for its curve section. CONCLUSIONS: Since the pavement marking speed-reduction treatment has been partially proven to be effective from this research, we expect to expand this treatment and re-confirm the effect from a long-term perspective in the future.

When the Road Layout Becomes Persuasive for the Road Users: A Functional Study on Safety and Driver Behaviour

The paper describes a research aimed at investigating drivers’ behaviours in two experimental setups, a real and a virtual environment. A road layout characterized by a S-shaped curve has been considered. The aim of the research was to appraise the relationship between the human behaviour and the road geometry. First of all, the results show a delayed speed adaptation when approaching the same curve in various conditions, in both environments. The authors investigate when and where each driver acts, and how his action is influenced by the perception of the layout, as it is guaranteed by markings (standard and reinforced by retroreflective post-delineators). Different driving scenarios are examined, concluding that improved road markings: usually permit a better perception of the road, especially of the curve stretches, and a general reduction of average speed; sometimes have a not positive effect, specifically where there is a variation of the size of the roadway; have a negative role on the long straights; decrease the scattering of driver behaviours. The research also suggests a practical criterion for selecting calibration sections of the speed diagrams, in order to assure a good accordance between virtual and real environment.

Perceptual Measures to Influence Operating Speeds and Reduce Crashes at Rural Intersections: Driving Simulator Experiment

The aim of this paper is to investigate, by means of a dynamic driving simulator experiment, the behavior of road users at rural intersections in relation to perceptual measures designed for increasing hazard detection. In the experiment 10 configurations of tangents were tested: Alt1, base tangent; Alt2, four-leg base intersection; Alt3, intersection with reduced sight distance; and Alt4 through Alt10, intersections with perceptual treatments. The Virtual Environment for Road Safety high-fidelity dynamic-driving simulator, operating at the Technology Environment Safety Transport Road Safety Laboratory located in Naples, Italy, was used. Analysis of the results used two approaches: (a) explorative description of data by cluster analysis and (b) inferential procedures about population using statistical tests. Results showed that the speed behavior in the tangents was significantly affected by the presence of the intersections and by the perceptual treatments. Intersections without perceptual treatments significantly affected driver speeds in the 250 m preceding the intersection. Perceptual treatments helped the driver to detect the intersection earlier and to slow down. Dragon teeth markings, colored intersection area, and raised median island performed better than the other perceptual treatments. They produced significant average speed reduction in the 150 m preceding the intersection ranging between 16 km/h and 23 km/h. Study results support real-world implementation of perceptual measures in rural intersections because they are low-cost, fast implementation measures with a high potential to be cost-effective.

Effectiveness of Speed-Monitoring Displays in Speed Reduction in School Zones

Speeding is one of the major causes of the frequent and severe traffic accidents that occur in school zones. Two field studies were conducted to assess the short-term and long-term effectiveness of speed-monitoring displays (SMDs) for speed reduction in school zones. The performance difference is discussed according to several dependent variables, including the average speed, the 85th percentile speed, and the distribution of speeds. The short-term study results showed that the speed of vehicles began to be reduced when the driver recognized the presence of an SMD, and the average speed was reduced by about 17.5% (8.2 km/h) at the SMD location. This speed reduction was observed throughout the day, regardless of the time of day. A similar performance trend was identified from the long-term study results, but the average speed reduction was slightly reduced to 12.4% (5.8 km/h) at the SMD location. However, statistical analyses showed that the speed differences were statistically significant. In addition, analysis of the results of the speed distribution showed that the number of speeding vehicles was greatly reduced after the SMD was installed, and the 85th percentile speed also decreased from 54.3 to 46.3 and 45.0 km/h in the short-term and the long-term studies, respectively. Therefore, it was concluded that the application of SMDs in school zones produced a positive impact on the drivers’ behaviors for a long period of time.

Effectiveness of Speed-Monitoring Displays in Speed Reduction in School Zones

Speeding is one of the major causes of the frequent and severe traffic accidents that occur in school zones. Two field studies were conducted to assess the short-term and long-term effectiveness of speed-monitoring displays (SMDs) for speed reduction in school zones. The performance difference is discussed according to several dependent variables, including the average speed, the 85th percentile speed, and the distribution of speeds. The short-term study results showed that the speed of vehicles began to be reduced when the driver recognized the presence of an SMD, and the average speed was reduced by about 17.5% (8.2 km/h) at the SMD location. This speed reduction was observed throughout the day, regardless of the time of day. A similar performance trend was identified from the long-term study results, but the average speed reduction was slightly reduced to 12.4% (5.8 km/h) at the SMD location. However, statistical analyses showed that the speed differences were statistically significant. In addition, an...

Automatic Speed Management in the Netherlands

Speed warnings and enforcement can be administered locally on a road stretch, and on a road network. Local automatic speed warning at an urban intersection reduced the mean speed by 5 km/hr. Theoretically, a reduction in accidents of 25 to 65 percent can be achieved. At a rural intersection, the speed limit was reduced from 100 to 70 km/hr. An automatic sign warns speeding cars; this resulted in a lowering of the mean speed from around 80 to 63 km/hr. An automatic speed warning and enforcement system on two-lane rural road stretches where the speed limit is 80 km/hr resulted in a reduction of the mean speed from 78 to 73 km/hr; the percentage of speeders decreased from 40 to 10 percent. The total number of accidents was reduced by 35 percent. This effect was almost the same three years after concluding the experiment. The problem of vandalism could be diminished by mounting the camera on a high pole, mechanically preventing climbing of the pole, automatic detection of vandalism, and wireless communication to a nearby police station. Enforcement of speed on a provincial road network using radar and camera exclusively from a parked unmarked car was conducted in three provinces. A sign downstream of the enforcement site read “Your speed has been checked. Police.” Periodic information campaigns were conducted to increase awareness of the risk of being caught. The result was a reduction of average speed by 4 to 5 km/hr, although the percentage of speeders is still high a reduction from 40 to 30 percent. This type of enforcement is accepted by 75 percent of the drivers. Greater priority for speed enforcement is needed in addition to automating enforcement and processing to increase efficiency.

Appraisal of traffic stream friction

This paper presents a simulation model to evaluate the quality of traffic flow. The evaluation is based on counts of the number of potential speed changes on a stretch of road and the estimated number of times a vehicle is limited in changing lanes. In order to describe the behaviour of the traffic flow process, two models were developed. One model describes vehicle arrival patterns on a road cross section; the other model, vehicle speeds. The stochastic process of speed is described as an autoregression process, whereas vehicle arrivals are presented as a Markovian process. Simulation results indicate an increase in traffic stream friction with an increase in vehicle-speed standard deviation and a reduction in average speed. The dependence of vehicle arrivals in adjacent lanes seems to increase the amount of friction in each lane. The simulation model developed enables a comparison of the quality of traffic flow at different sites, as well as a before-and-after study of any particular site.

Soaring Migration of the Common Crane Grus grus Observed by Radar and from an Aircraft

Migrating Crane flocks were tracked over southern Sweden with a tracking radar and an aircraft. Air speeds and rates of climb in thermals were recorded, and behaviour was observed. The Cranes flew faster than soaring theory would predict, and also used varying amounts of muscle power on the interthermal glides. We estimate that their use of thermals and partially powered glides substantially reduced the energetic cost of flying unit distance, but at the expense of a reduction in average speed. The behaviour required for soaring is elaborate, and the selection pressures for and against it are discussed. Crane flocks were seen to split up and recombine in a way which suggested that they were not stable social units.

Mortality of Wildlife on a Texas Highway

Considerable interest has developed of late in the problem of wildlife mortality on our public highways (see Dickerson, L. M., the JOURNAL OF WILDLIFE MANAGEMENT, 1939, vol. 3, p. 104). In an attempt to gain some measure of the losses on the highways of Texas, I kept daily records (except for July and August) from February 1, 1938, to January 31, 1939, of mammals run down by motorists on the six miles of concrete highway between College Station and Bryan in Brazos County. Traffic on this section of highway is heavier than average, increasing the hazard to wildlife, but this factor is compensated for in part by the relative scarcity of most kinds of mammals in this section of the state. I consider my data as probably slightly less than average for a similarly constructed six-mile section of highway in some other part in Texas, as, for example, the TransPecos region. On unimproved highways, of course, the losses would tend to be much less, for it is common knowledge that the rate of mortality to wildlife, and man as well, increases directly with the degree to which a highway is improved for rapid transit. Disregarding the months of July and August in which no data were recorded, the average monthly loss of mammals was 5, or nearly 10 per mile-year. If my data be nearly average for similar sections of fast highway in other parts of the state, the total number of mammals (not counting man) killed each year on the 15,675 miles of hard surfaced highways in Texas is 156,750. If w assume that a reduction of average speed on the highway from 50 m.p.h. to 30 m.p.h. will reduce highway mortality of wildlife from 10 a mile-year to, say, 4, the yearly loss on the 5,790 miles of graveled and unimproved roads in the State would amount to 23,160. Add this to the figure derived for the fast highways, and we get a total of 179,910. This figure is for mammals alone. No r cord was kept of the birds, reptiles, and amphibians run down by motorist , but I gained the impression that during the ten months of observation the loss of birdlife was only about onef fth that of mammals; reptiles, however, especially the painted terrapin (Terrapene ornata), fared much worse than did the mammals.