Improving Work Zone Safety Through Speed Management PDF Download

Author: Norman M. Sommers
Publisher:
ISBN:
Category : Road work zones
Languages : en
Pages : 78

View

Book Description
Safety hazards are increased in highway work zones as the dynamics of a work zone introduce a constantly changing environment with varying levels of risk. Excessive speeding through work and maintenance zones is a common occurrence which elevates the dangers to both drivers and motorists in the work zone. Although most work zones are controlled by reduced speed limits or state law enforcement, driver adherence to these regulations and laws in very minimal, especially in work zones. Several studies have shown a correlation between speeding in work zones and traffic crashes which lead most traffic safety professionals to conclude that excessive speeding and speed variance are the contributing factors in a large percentage of traffic crashes, injuries or fatalities. The most influential factor in achieving speed compliance in the work zone is the driver's perception of heightened risk. The main objective of this study was to determine the safest and most effective countermeasure for the reduction of vehicular speeds within construction and maintenance work zones. The purpose of the simulator experiment was to determine the effectiveness of 20 countermeasures on the reduction of speed through work zones in a controlled laboratory setting. The literature review identified several past research studies utilizing speed reduction countermeasures in work zones and under normal traffic conditions. From this review, 20 countermeasures were selected for evaluation based upon discussions with ODOT personnel.The post hoc tests indicated that the presence of construction workers, presence of construction vehicles, law enforcement, speed photo enforcement and shifting lanes were most effective at reducing speeds in work zones. The least effective speed reduction countermeasures included 3 sets of 3 rumble strips, concrete barriers, other channelizing devices and changeable message signs with speed reductions less than 10 mph.

Author: Stirling P. Stackhouse
Publisher:
ISBN:
Category : Motor vehicle drivers
Languages : en
Pages :

View

Book Description

Author: John Anthony Gambatese
Publisher:
ISBN:
Category : Road work zones
Languages : en
Pages :

View

Book Description
Freeway preservation projects typically require construction workers to conduct their work in close proximity to ongoing traffic and often reduce traffic flow to a single lane while work is undertaken in an adjacent lane. Due to the short-term nature of these work zones, temporary traffic control measures typically consist of a line of cones, blocker vehicles, and impact attenuators. Work zones place both the workers and passing motorists at risk of injury. The Oregon Department of Transportation conducted a research study to investigate the impact of selected traffic control devices on vehicle speeds within highway paving project work zones. The research study, which follows a similar study conducted a year earlier, centered around two case studies on multi-lane paving projects in Oregon. On each case study, the researchers implemented combinations of multiple traffic control devices ("Speed 50" signs, PCMS signs, and radar speed displays) and evaluated their impact on vehicle speed. The research findings suggest using a combination of reduced speed limit signs, radar speed monitoring displays, and PCMS signs on either trailers or rollers. The results of the present study complement those of the prior study and, combined with the prior study, provide ODOT with guidance on the selection of traffic control measures for freeway preservation projects.

Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 100

View

Book Description
Highway work zones have been plagued with increasing numbers of accidents in recent years. Drivers' lack of compliance with speed restrictions within work zones has been cited as one of the major contributing factors to this trend. The conventional practice for regulating work zone speeds has been static signing procedures (using regulatory or advisory speed signs). It has been found that drivers do not slow down in response to these static control measures. Changeable message signs (CMS) equipped with a radar unit can be used to display specific warning messages to speeding drivers. The radar unit detects the speed of each vehicle entering the work zone and can be programmed to activate the CMS if the speed of the vehicle exceeds a preset threshold value. This offers a more dynamic speed control environment and therefore may prove to be more effective in influencing drivers to reduce their speeds. This report is the second phase of a longitudinal research study. The first phase of the project, conducted by Garber and Patel, examined the short term effectiveness of CMS in reducing vehicle speeds in work zones. That research established that the CMS (with the radar unit) is more effective in reducing speeds in work zones than the standard Manual on Uniform Traffic Control Devices (MUTCD) signs. This study, while attempting to replicate the results obtained in phase I of the project, concentrated on evaluating the effect of duration of exposure of the CMS with radar on its effectiveness in reducing speeds and influencing speed profiles in work zones. The impact of length of the work zone and vehicle type on speed reductions was also studied. Three work zone sites in southwest Virginia, two on Interstate 81 and one on a primary highway on Route 19, were selected for the study. Speed and volume data for the population were collected using automatic traffic counters at the beginning, middle and end of each work zone. In addition, the speeds of individual drivers who triggered the CMS by exceeding the threshold speed were also recorded (using a video camera) at two other locations within the work zone to study the behavior of high speed drivers in particular and to compute their average speed reduction in response to the warning message. The results of the study indicate that the duration of exposure of the CMS does not have a significant impact on speed characteristics and driver behavior. Therefore, the CMS continues to be effective in controlling speeds in work zones for projects of long duration. It was also determined that the drivers exceeding the speed limit, in both interstate work zones have on average reduced their speeds by around 12.86 km/h (8 mph) at the middle of the work zone. At the third site (Route 19) the speed reductions at the middle of the work zone were about 16.08 km/h (10 mph). It was also found that there were no distinctive differences among the different types of vehicles with regard to speed reduction. The study also established that in longer work zones, drivers who reduced their speeds in response to the speed control effort frequently have a tendency to speed back up as they approach the end of the work zone. This indicates that very long work zones might warrant the installation of a second CMS to maintain speed reductions through the work zone.

Author: John W. Shaw
Publisher:
ISBN:
Category : Road work zones
Languages : en
Pages : 152

View

Book Description
This synthesis documents information regarding the current state of practice for work zone speed management. The report compiles data, procedures, techniques, and technical issues related to observing and comparing work zone speeds. The speed management measures have been organized into four categories: engineering, operational, enforcement, and public education and outreach. Information included in this study was acquired through a review of the literature, two surveys of state department of transportation representatives in all states, a compilation of state agency public information campaigns, and follow-up interviews with select survey respondents from several U.S. states and one Canadian province.

Author: R. F. Benekohal
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 114

View

Book Description
This report summarizes and evaluates the important findings from the literature review of the studies on work zone speed control techniques. The following treatments are included in this report: 1) flagging, 2) lane width reduction, 3) law enforcement, 4) changeable message signs (CMS), 5) rumble strips, and 6) flashing beacons. The effects of the speed control treatments on speed and traffic flow are evaluated based on: A) experiences with treatment, B) effects of treatment on speed, C) effectiveness of treatment, and D) comments about treatment. A brief description of the conditions under which the treatments were applied is provided, and the speed reduction effects of each technique are discussed. A reference matrix was prepared to identify publications related to each type of speed reduction treatment used in work zones.

Author: R. F. Benekohal
Publisher:
ISBN:
Category : Express highways
Languages : en
Pages : 82

View

Book Description
The objectives of this project were to determine the effectiveness of speed control methods and study traffic behavior in construction zones. This report provides a brief introduction and summary of findings from the following reports which were prepared as part of this study: (1) Evaluation and Summary of Studies in Speed Control Methods in Work Zones. (2) Evaluation of a Radar-Activated Horn System for Speed Control in Highway Maintenance Operations. (3) Survey of Driver's Opinion about Work Zone Traffic Control on a Rural Highway. (4) Speed Reduction Effects of Drone Radar in Rural Interstate Work Zones. (5) Speed Reduction Effects of Changeable Message Signs in a Construction Zone. (6) Effects of Police Presence on Speed in a Highway Work Zone: Circulating Marked Police Car Experiment. (7) Evaluation of Work Zone Speed Limit Signs with Strobe Lights. (8) Speed Reduction Profiles of Vehicles in a Highway Construction zone. Data only for those vehicles in free flow traffic are used for speed reduction evaluation. A vehicle was considered to be in free flow traffic when its time headway was greater than 5 seconds.

Author: R. F. Benekohal
Publisher:
ISBN:
Category : Express highways
Languages : en
Pages : 94

View

Book Description
This study evaluated the vehicular speed reduction effects of displaying speed limit and information messages on a changeable message sign (CMS) placed inside the work activity area in a work zone for a one lane closure on a rural interstate highway. It also examined the additional effects of using two CMS devices compared to one CMS. The following three experiments were conducted: (1) One CMS in advance of the work zone (Experiment 1), (2) One CMS inside the work activity area (Experiment 2), and (3) Two CMSs inside the work activity area (Experiment 3). Displaying speed limit and information messages on CMSs placed in the work activity area was effective in reducing the average speed and percentages of vehicles with excessive speeds. Comparing the results from Experiments 2 and 3 indicated that displaying the CMS messages reduced the speed of cars immediately after passing the CMS, but not at a point far from the CMS. Although trucks did not consistently reduce their speeds near the first CMS, trucks traveled at reduced speeds after passing the CMS. Cars and trucks reduced their speeds by as much as 5 and 4 mph, respectively, near the CMS. The speed reduction depended on the travel speed of the vehicles. Placing the CMS in the work activity area was more effective than putting it in advance of the work zone.

Author: T. H. Maze
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 146

View

Book Description
The Iowa Department of Transportation (DOT) has made improving work zone (WZ) safety a high priority. Managing vehicle speeds through work zones is perceived to be an important factor in achieving this goal. A number of speed reduction techniques are currently used by transportation agencies throughout the country to control speeds and reduce speed variation at work zones. The purpose of this project is to study these and other applicable work zone speed reduction strategies. Furthermore, this research explores transportation agencies' policies regarding managing speeds in long-term, short-term, and moving work zones. This report consists of three chapters. The first chapter, a literature review, examines the current speed reduction practices at work zones and provides a review of the relevant literature. The speed control strategies reviewed in this chapter range from posting regulatory and advisory speed limit signs to using the latest radar technologies to reduce speeds at work zones. The second chapter includes a short write-up for each identified speed control technique. The write-up includes a description, the results of any field tests, the benefits and the costs of the technology or technique. To learn more about other state policies regarding work zone speed reduction and management, the Center for Transportation Research and Education conducted a survey. The survey consists of six multipart questions. The third chapter provides summaries of the response to each question.

Author: Nicholas J. Garber
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 108

View

Book Description
Work zone speeds have customarily been regulated by standard regulatory or advisory speed signs. However, most drivers do not slow down in response to these static speed control measures. The changeable message sign (CMS) with radar unit has dynamic capabilities which may be more effective in altering driver behavior. The radar, attached directly to the CMS, determines the actual speed of individual vehicles in the traffic stream. Upon detecting a speed higher than a preset threshold limit, the CMS can display a personalized warning message. This study evaluated the effectiveness of the CMS with radar unit in reducing work zone speeds. Four CMS messages designed to warn drivers that their speed exceeded the maximum safe speed were tested at seven work zones on two interstate highways in Virginia. Speed and volume data for the whole population traveling through the work zone were collected with automatic traffic counters. To assess the effect of CMS on high-speed drivers in particular, vehicles that triggered the radar-activated display were videotaped as they passed through the work zone. Using the data obtained from the traffic counters and videotapes, speed characteristics were determined at the beginning, middle, and end of the work zone. These characteristics were computed for the whole population and for high-speed vehicles separately. Statistical tests were then conducted using these speed characteristics to determine whether significant reductions in speed accompanied the use of CMS. Odds ratios were first calculated to compare the odds for speeding when using CMS with the odds for speeding when using the Manual on Uniform Traffic Control Devices (MUTCD) signing only. These odds ratios indicated that CMS effectively reduced the number of vehicles speeding by any amount, by 5 mph or more, and by 10 mph or more in the work zone. When analysis of variance was used to compare speeds when using the CMS with speeds when using MUTCD signing only, all of the speed characteristics average speeds, 85th percentile speeds, speed variance, and the percentage of vehicles speeding by any amount, by 5 mph or more, and by 10 mph or more were reduced with any of the four CMS messages. In some cases, these reductions were not significant at a= 0.05. The messages were rated according to their level of effectiveness in the following order: [1] YOU ARE SPEEDING SLOW DOWN, [2] HIGH SPEED SLOW DOWN, [3] REDUCE SPEED IN WORK ZONE, and [4] EXCESSIVE SPEED SLOW DOWN. Finally, t tests were conducted using the speed data obtained for the high-speed vehicles, and at a significance level of ct 0.05, all of the messages were effective in significantly reducing the average speeds of those vehicles traveling 59 mph or faster in a 55 mph work zone when compared to MUTCD signing only.