scholarly journals Effects of reducing and enforcing speed limits in selected arterial roads in Bogota

2021 ◽  
Vol 8 (2) ◽  
pp. 50-71
Author(s):  
José Segundo López ◽  
David Perez-Barbosa ◽  
Natalia Lleras ◽  
Darió Hidalgo ◽  
Claudia Adriazola-Steil
Keyword(s):  
Geographical Distribution ◽  
Speed Limit ◽  
Traffic Crashes ◽  
Speed Limits ◽  
Speed Reduction ◽  
Average Speed ◽  
Management Measure ◽  
Speed Management ◽  
The City

In Bogota, the speed limit in five corridors with the highest concentration of traffic crashes victims in the city was reduced from 60 to 50 km/h since November 2018. The average speed reduction in the corridors with speed management was 1.48 km/h during daytime and 3.04 km/h during nighttime. In arterial corridors without speed management, the average speed reduction was 0.7 km/h during daytime and 2.2 km/h during nighttime. The speed management measure influenced a reduction of 16.6% in the number of fatalities and an 10.5% increase of crashes with injuries. The severity of the crashes decreased. The average count of run over crashes was also reduced by 10%. Changes in the geographical distribution of crashes with injuries and fatalities along the corridors with speed management indicate the necessity to implement stricter enforcement measures to increase the effectiveness of speed management operations during nighttime.

scholarly journals Speed management as a measure to improve road safety on Polish regional roads

2017 ◽  
Vol 43 (3) ◽  
pp. 29-42 ◽  
Author(s):  
Stanisław Gaca ◽  
Sylwia Pogodzińska
Keyword(s):  
Road Safety ◽  
Speed Limits ◽  
Speed Reduction ◽  
Average Speed ◽  
Traffic Calming ◽  
Management Measures ◽  
Speed Management ◽  
Speed Up ◽  
Road Segments ◽  
Local Speed

The article presents the issue of the implementation of speed management measures on regional roads, whose character requires the use of different solutions than those on national roads. The authors briefly described speed management measures, the conditions for their implementation and their effectiveness with reference to environmental conditions and road safety. The further part of the paper presents selected results of the authors' research into the speed on various road segments equipped with different speed management measures. The estimations were made as to the impact of local speed limits and traffic calming measures on drivers' behaviour in free flow conditions. This research found that the introduction of the local speed limits cause reduction in average speed and 85th percentile speed up to 11.9 km/h (14.4%) and 16.3 km/h (16.8%) respectively. These values are averaged in the tested samples. Speed reduction depends strongly on the value of the limit and local circumstances. Despite speed reduction, the share of drivers who do not comply with speed limits was still high and ranged from 43% in the case of a 70 km/h limit, up to 89% for a 40 km/h limit. As far as comprehensive traffic calming measures are concerned, results show decrease in average speed and 85th percentile speed up to 18.1 km/h and 20.8 km/h respectively. For some road segments, however, the values of average speed and 85th percentile speed increased. It confirms that the effectiveness of speed management measures is strongly determined by local circumstances.

scholarly journals Speed Optimization vs Speed Reduction: the Choice between Speed Limits and a Bunker Levy

2019 ◽  
Vol 11 (8) ◽  
pp. 2249 ◽  
Author(s):  
Harilaos Psaraftis
Keyword(s):  
Greenhouse Gas ◽  
Ghg Emissions ◽  
Emissions Reduction ◽  
Speed Limit ◽  
Short Term ◽  
Speed Limits ◽  
Speed Reduction ◽  
Speed Optimization ◽  
Limit Option ◽  
Better Than

“Speed optimization and speed reduction” are included in the set of candidate short-term measures under discussion at the International Maritime Organization (IMO), in the quest to reduce greenhouse gas (GHG) emissions from ships. However, there is much confusion on what either speed optimization or speed reduction may mean, and some stakeholders have proposed mandatory speed limits as a measure to achieve GHG emissions reduction. The purpose of this paper is to shed some light into this debate, and specifically examine whether reducing speed by imposing a speed limit is better than doing the same by imposing a bunker levy. To that effect, the two options are compared. The main result of the paper is that the speed limit option exhibits a number of deficiencies as an instrument to reduce GHG emissions, at least vis-à-vis the bunker levy option.

scholarly journals Optimal Winter Speed Limit

2010 ◽  
Author(s):  
Suthipun Thaneseun ◽  
Seiichi Kagaya ◽  
Ken-etsu Uchida ◽  
Toru Hagiwara
Keyword(s):  
Regression Analysis ◽  
Cost Analysis ◽  
Operating Costs ◽  
Speed Limit ◽  
Speed Limits ◽  
Total Cost ◽  
Average Speed ◽  
Traffic Conditions ◽  
Optimal Average

This study aims to determine the optimal winter speed limit through the application of a cost analysis and by analysis of effects of road and traffic conditions. Initially, a cost analysis of travel time costs, vehicle operating costs, pollution costs, and accident cost was applied to determine optimal average speed on the basis of the minimum total cost. Then, the effects of road and traffic conditions were calculated by regression analysis. Finally, the optimal winter speed limits were achieved. In conclusion, we found that our model was reliable and the results were appropriate and sustainable for the long term.

Automatic Speed Management in the Netherlands

1996 ◽  
Vol 1560 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Hway-liem Oei
Keyword(s):  
Wireless Communication ◽  
Road Network ◽  
Speed Limit ◽  
Information Campaigns ◽  
Average Speed ◽  
Police Station ◽  
Rural Road ◽  
Speed Management ◽  
The Mean ◽  
Speed Enforcement

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.

scholarly journals The Effect of Posted Speed Limit on the Dispersion of Traffic Flow Speed

2019 ◽  
Vol 11 (13) ◽  
pp. 3594 ◽  
Author(s):  
Chao Gao ◽  
Jinliang Xu ◽  
Qunshan Li ◽  
Jie Yang
Keyword(s):  
Traffic Flow ◽  
Flow Speed ◽  
Traffic Volume ◽  
Free Flow ◽  
Speed Limit ◽  
Flow State ◽  
Speed Limits ◽  
Limit Values ◽  
Average Speed ◽  
The Road

Speed dispersion is an important indicator to portray the quality of traffic flow and is closely related to the road safety operation level. In order to clarify the influence of posted speed limits on the dispersion of traffic flow speed, three sections with speed limits of 80 km/h, 100 km/h and 120 km/h on the same expressway were selected for observation, and traffic volume, speed and other parameters were collected. The characteristic speeds, such as average speed, V15 and V85, were evaluation indicators, where V15 and V85 are the speeds of the 15th and 85th percentiles measured at the feature points of the road when the traffic is in a free-flow state and the weather is good. The relationship between different posted speed limit values and the above indicators was analyzed using the statistical analysis software, SPSS. The results show that the speed limit has a high correlation with the average speed of traffic flow, V15 and V85 in free-flow state, with the coefficient of determination being as high as 0.84, 0.85 and 0.92, respectively. In the restricted flow state, the factors affecting the driver’s driving speed are mainly the decrease in driving freedom caused by the increase of traffic volume rather than the speed limit value. In a free-flow state, when the posted speed limit is increased and the average speed and the V85 also increased by approximately the same magnitude. The posted speed limit values of 80 km/h, 100 km/h and 120 km/h correspond to the 90, 88 and 97 percentile speeds of the traffic flow, respectively. The higher the speed limit is, the larger the speed difference between V15 and V85 becomes. The results of the study are very useful for rationally determining the speed limit scheme under different traffic flows.

scholarly journals M7 to M2 Pre-congestion Speed Management

2021 ◽  
Vol 32 (4) ◽  
pp. 60-67
Author(s):  
Timothy Clark ◽  
Sam Gray
Keyword(s):  
Traffic Flow ◽  
Reporting System ◽  
Speed Limit ◽  
Speed Limits ◽  
Opportune Time ◽  
Speed Management ◽  
Calming Effect

This paper explores the development and implementation of the M7 to M2 pre-congestion speed limit management trial conducted on workdays between 26th June 2018 and 31st December 2018. This trial was the first of its kind in NSW and was implemented using a live loop reporting system utilising key trigger values (specific loop metrics) to identify the opportune time to reduce speed limits prior to flow breakdown. Through measuring the rate at which speeds dropped during flow breakdown, the heatmap footprint of congestion, and the instance of congestion related crashes it was established the trial was able to have a calming effect on traffic flow and reduce the overall footprint of congestion.

scholarly journals SETTING SPEED LIMITS IN INTERURBAN SINGLE-CARRIAGEWAY HIGHWAYS USING EXPERT’S JUDGMENT

Transport ◽  
2016 ◽  
Vol 31 (2) ◽  
pp. 282-294
Author(s):  
Ana Bastos Silva ◽  
Álvaro Seco ◽  
Nuno Gregório
Keyword(s):  
Decision Making ◽  
Decision Support ◽  
Choice Model ◽  
Selection Process ◽  
Motor Vehicles ◽  
Decision Making Process ◽  
Final Decision ◽  
Speed Limit ◽  
Speed Limits ◽  
Speed Management

Until recently, the design of road infrastructure involved mainly concerns related to the base speed value and to requirements ensuring a high level of service. Currently, it is widely accepted that only an integrated approach is able to take into account the interests and needs of all the involved stakeholders, namely the need of traffic fluidity by motor vehicles, and quality of life and safety associated to other users and local residents. This vision has been leading to different speed management approaches, particularly in relation to the setting of the appropriate and coherent speed limits along extensive routes. In this context, this study is part of a broader research program aimed to develop a methodology of speed management with a widespread use applied to single carriageway roads in interurban areas, crossing different road surrounding environments with varying rural, urban or mixed characteristics. More specifically, this research line is focused on the development of a decision-support methodology for the definition of the appropriate speed limit, based on the drivers’ willingness to naturally accept successive changes in the speed limits in successive stretches of the roads. This decision-making process necessarily involves a broad set of variables and factors that might be divided in two fundamental components: (1) road geometry, and (2) interaction between the road and its surrounding environment. The effect related to the geometric characteristics has already been extensively studied, thus, this paper is focused on speed limit modelling having exclusively into account the latter component, leaving geometryrelated considerations to the final decision-making process. A MultiNomial Logit (MNL) discrete choice model was developed. The modelling work was carried out using a case study involving 55.4 km and 11 km more, for validation purposes – of rural roads crossing different environments. The model was estimated based on the judgments of fourtraffic safety experts applied to each direction of each road stretch (200 m long). Before the modelling development, a factor analysis involving the whole set of variables was carried out, in order to detect not directly observable common features on its structure that may influence the final outcome of model estimation. This analysis allowed to corroborate the overall variable selection process. The developed model adjusts quite well to the data with McFadden pseudo-R2 of 0.447. Without loss of explaining power it was possible to avoid the presence of subjectivity related to a qualitative evaluation of some explanatory variables, greatly enhancing the model’s robustness and transferability to other locations and countries. The new modelling structure also facilitates the interpretation of the validation results and enables the models to be developed to represent different levels of safety related sensitivity existent amongst the expert community, by using a ‘conservative expert’ evaluation. The results validation has showed the models to be robust and useful as decision support tools applied to speed limits’ evaluation processes.

scholarly journals Evaluating the citywide Edinburgh 20mph speed limit intervention effects on traffic speed and volume: A pre-post observational evaluation

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261383
Author(s):  
Glenna F. Nightingale ◽  
Andrew James Williams ◽  
Ruth F. Hunter ◽  
James Woodcock ◽  
Kieran Turner ◽  
...  
Keyword(s):  
Road Traffic ◽  
Statistical Significance ◽  
Evidence Base ◽  
Time Of Day ◽  
Contributory Factor ◽  
Speed Limit ◽  
Volume Data ◽  
Speed Limits ◽  
Traffic Speed ◽  
The City

Objectives Traffic speed is important to public health as it is a major contributory factor to collision risk and casualty severity. 20mph (32km/h) speed limit interventions are an increasingly common approach to address this transport and health challenge, but a more developed evidence base is needed to understand their effects. This study describes the changes in traffic speed and traffic volume in the City of Edinburgh, pre- and 12 months post-implementation of phased city-wide 20mph speed limits from 2016–2018. Methods The City of Edinburgh Council collected speed and volume data across one full week (24 hours a day) pre- and post-20mph speed limits for 66 streets. The pre- and post-speed limit intervention data were compared using measures of central tendency, dispersion, and basic t-tests. The changes were assessed at different aggregations and evaluated for statistical significance (alpha = 0.05). A mixed effects model was used to model speed reduction, in the presence of key variables such as baseline traffic speed and time of day. Results City-wide, a statistically significant reduction in mean speed of 1.34mph (95% CI 0.95 to 1.72) was observed at 12 months post-implementation, representing a 5.7% reduction. Reductions in speed were observed throughout the day and across the week, and larger reductions in speed were observed on roads with higher initial speeds. Mean 7-day volume of traffic was found to be lower by 86 vehicles (95% CI: -112 to 286) representing a reduction of 2.4% across the city of Edinburgh (p = 0.39) but with the direction of effect uncertain. Conclusions The implementation of the city-wide 20mph speed limit intervention was associated with meaningful reductions in traffic speeds but not volume. The reduction observed in road traffic speed may act as a mechanism to lessen the frequency and severity of collisions and casualties, increase road safety, and improve liveability.

scholarly journals Pilot study to evaluate school safety zone built environment interventions

2021 ◽  
pp. injuryprev-2021-044299
Author(s):  
Linda Rothman ◽  
Rebecca Ling ◽  
Brent E Hagel ◽  
Colin Macarthur ◽  
Alison K Macpherson ◽  
...  
Keyword(s):  
Pilot Study ◽  
Built Environment ◽  
School Safety ◽  
Repeated Measures ◽  
Speed Limit ◽  
Post Intervention ◽  
Speed Limits ◽  
Arrival Times ◽  
Dangerous Driving ◽  
The City

BackgroundSchool safety zones were created in 2017 under the City of Toronto’s Vision Zero Road Safety Plan. This pilot study examined the effect of built environment interventions on driver speeds, active school transportation (AST) and dangerous driving.MethodsInterventions were implemented at 34 schools and 45 matched controls (2017–2019). Drivers travelling over the speed limit of >30 km/hour and 85th percentile speeds were measured using pneumatic speed tubes at school frontages. Observers examined AST and dangerous driving at school arrival times. Repeated measures beta and multiple regression analyses were used to study the intervention effects.ResultsMost schools had posted speed limits of 40 km/hour (58%) or ≥50 km/hour (23%). A decrease in drivers travelling over the speed limit was observed at intervention schools post-intervention (from 44% to 40%; OR 0.79, 95% CI 0.66 to 0.96). Seventy-one per cent of drivers travelled >30 km/hour and the 85th percentile speed was 47 km/hour at intervention schools, with no change in either postintervention. There were no changes in speed metrics in the controls. AST increased by 5% (OR 1.22, 95% CI 0.97 to 1.54) at intervention schools. Reductions in dangerous driving were observed at all schools.ConclusionsPosted speed limits were >30 km/hour at most schools and high proportions of drivers were travelling above the speed limits. There were reductions in drivers exceeding the speed limit and in dangerous driving, and modest increased AST post intervention. Bolder interventions to slow traffic are required to effectively reduce speeding around schools, which may increase safe AST.

Raising Speed Limits on Rural Highways: Process for Identification of Candidate Nonfreeway Segments

2017 ◽  
Vol 2618 (1) ◽  
pp. 58-68 ◽  
Author(s):  
Jonathan J. Kay ◽  
Timothy J. Gates ◽  
Peter T. Savolainen
Keyword(s):  
Selection Criteria ◽  
Primary Objective ◽  
Segment Length ◽  
Speed Limit ◽  
Speed Limits ◽  
Rural Highways ◽  
Speed Reduction ◽  
Safety Research ◽  
Lane Width ◽  
Design Speed

Speed limits on rural highways have recently been on an upward trend nationwide as 25 states have increased speed limits on such roadways between 2011 and 2016. In January 2017, Michigan House Bill 4423 (Public Act 445) was signed into law, which required speed limits to be raised from 55 to 65 mph on at least 900 mi of Michigan’s state-maintained nonfreeways. The specific highway segments were to be selected by the Michigan Department of Transportation (DOT) within 1 year of enactment on the basis of an assessment of travel speeds and safety. Research was undertaken to develop a process to select candidate highway segments for speed limit increases in Michigan. The primary objective was to identify rural highway segments with comparatively low safety risks for which costly geometric upgrades, specifically horizontal or vertical realignment, would be avoided. Ultimately, 12 factors and associated selection criteria were used to identify the candidate segments. These factors included segment length, total crash rate, injury crash rate, severe (fatal and A-injuries) crash rate, horizontal curvature, speed reduction zones, no-passing zones, schools (kindergarten through eighth grade), driveway density, lane width, paved shoulder width, and signalized intersections. Application of the candidate selection criteria to the Michigan DOT nonfreeway network yielded 772.8 centerline miles along 33 candidate segments, which represented approximately one-eighth of the network mileage currently posted at 55 mph. To avoid substantial geometric upgrade costs, speed limit increases were specifically not recommended for segments that would require horizontal or vertical realignment to achieve design speed compliance with the increased speed limit.

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