Communications: electrical – Traffic control indicator – Portable
Reexamination Certificate
2001-06-29
2003-05-06
Lee, Benjamin C. (Department: 2632)
Communications: electrical
Traffic control indicator
Portable
C340S908100, C340S907000, C340S933000
Reexamination Certificate
active
06559774
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a traffic control system and method for construction work zones.
(b) Description of the Prior Art
Traffic accidents on a given section of roadway greatly increase while road work is performed in or near the roadway section. A work zone safety system is intended to reduce accidents at a construction zone. When traffic moves slowly, it is instinctive for motorists to attempt to pass slower moving vehicles in order to decrease the time of their journey. This instinct can lead to problems in a work zone because one lane is closed due to construction. In a work zone, the passing motorist will likely have difficulty re-entering traffic which may lead to an accident with another vehicle or an accident with the construction crew.
Lane restrictions, traffic speed fluctuations, bi-directional traffic flow, vehicles entering and exiting the roadway, and the general distracting surroundings of a work zone contribute to the propensity of accidents in and around roadway work zones. This propensity for accidents poses a very real risk to road construction crews, utility crews, maintenance workers, and other personnel in the vicinity of a work zone. It is not uncommon for accident rates to increase about 50% or more during times of constructions, and these accidents are increasingly causing injury and death to work zone personnel. Along with the human tragedy of the increased work zone related injuries and deaths, contractors suffer economically as well from worker's compensation rate increases, (in Canada) increased tort liability, and decreases in worker productivity and morale as work zone personnel pay greater attention to oncoming traffic and less attention to their work assignments.
Various devices and techniques are known which attempt to alert drivers to approaching roadway hazards. These devices were designed to make drivers more aware of their surroundings and/or to reduce the speed of vehicles approaching roadway hazards. These prior art techniques included: regulatory and advisory signage; dynamic speed limit signage; mock-up police cars; high visibility clothing; and traffic flow diversion devices, to name but a few. While these prior art devices and techniques undoubtedly deterred countless additional work zone related accidents, those devices were directed solely at alerting drivers of an approaching hazard. Those devices had no way to warn work zone personnel if, or when, a vehicle strayed from a designated traffic lane and breached the work zone perimeter.
One device, however, which was well-known, attempted to signal highway workers when an errant vehicle entered the work zone. The device included an infrared signal with a reflective cone, or an ultrasonic beam, to detect a vehicle passing thereby. The infrared signal or ultrasonic beam was positioned “upstream” from the work zone and was placed at about 90° to the oncoming traffic. This detector was in communication via a wireless data link to a siren of about 120 decibel which was positioned within the work zone. When a vehicle was detected upstream, a signal was transmitted to the siren and the siren sounded an audible warning. Another embodiment of this device used a pneumatic tube which was laid across the roadway in place of the infrared or ultrasonic beam. However, the harsh environment of the roadway work zone proved too large an obstacle for this device efficiently to warn workers.
The problems with this warning device were numerous. First, most work zones were very noisy. In addition to the traffic noise and wind along any stretch of roadway, many work zones used heavy construction machinery, and jack hammers, shot blaster, and concreted cutters which create a tremendous amount of noise. Because the U.S. Occupational Safety and Health Administration (“OSHA”) standards required operators of this machinery to wear hearing protection, the operators were unable to hear the audible warning over the noise of the equipment they were operating and through their hearing protection. Further, even without hearing protection, personnel in the vicinity of this machinery and equipment often did not hear the audible warning.
Secondly, this warning device suffered several integrity problems. Because the device used a single detector positioned “upstream” from the work zone and at about 90° to approaching traffic, it was possible for vehicles to enter the work zone without tripping the detector. Moreover, the heat and audible noise produced by work zone equipment and passing traffic would interfere with such infrared and ultrasonic detectors, thereby causing false detections. Further, the distance between the detector and the siren necessitated a wireless data link therebetween. Modern work zones are flooded with electromagnetic noise within the popular communication frequencies. The frequent use of walkie-talkies by work zone personnel, portable and cellular telephones by work zone personnel and passing traffic, and CB and short wave radio by passing vehicular and air traffic would trigger the siren causing a significant problem with false alarms. Furthermore, this transmission required FCC compliance as well.
Other devices intended for alerting work zone personnel to vehicles breaching the work zone perimeter relied on audible alarms, despite the high level of noise which pervade the work zones, and despite OSHA regulations relating to hearing protection which substantially degraded the effectiveness of audible alarms. Although several of the devices which alerted drivers, rather than personnel, to approaching roadway hazards employed a variety of rotating and/or flashing lights to attract the drivers' attention, such lights have never been used to convey information to the work zone personnel. This was perhaps for two reasons. Firstly, most believed that, by working in a roadway work zone where numerous flashing signs and rotating lights were present for alerting drivers to the presence of the work zone, the work zone personnel had become immune to optical warning signals, and cannot readily distinguish a typical warning light for alerting drivers from a warning light for alerting the personnel of a hazard. Secondly, because the attention of the work zone personnel was supposed to be on the task they were paid to perform, one cannot realistically have expected the worker to be looking in the direction of a warning light at all times for quickly perceiving a warning signal. For example, if a typical rotating incandescent light was used to convey the intrusion of a vehicle into the work zone, it was highly probable that a worker operating a jack hammer would be looking down and away from the light while performing this task, and thus would not perceive the warning signal at all, or at least not within sufficient time to evacuate the work zone or otherwise evade the approaching vehicle.
Generally, in the event that vehicles alternately passed on one-side road section under construction from opposite directions, traffic signals were temporarily provided at both ends of the section, thereby conducting a traffic control. One of the representative systems of such prior art was one wherein traffic signals and detector means, e.g., pressure sensors at both ends of the section were provided for detection of the number of vehicles passing therethrough, thus extending the lighting time of green signals at the heavier traffic end. A signal controller circuit included a signal device which changed indication of signals by means of vehicle detector means, e.g., light sensor or the like provided adjacent to the signals. Further, a system was disclosed for alternately switched traffic signals controller device having a set of traffic signals which was so operated that while one traffic light at passage allowed end was green, the other traffic signal at no passage allowed end was red or against and detector means were provided for detection of vehicles passing through the section. Furthermore, a traffic signal device was also provided at both ends o
Bergan Terry
Klashinsky Rod
International Road Dynamics Inc.
Lee Benjamin C.
LandOfFree
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