Communications: electrical – External condition vehicle-mounted indicator or alarm – Highway information
Reexamination Certificate
1999-09-07
2002-06-18
Swarthout, Brent A. (Department: 2632)
Communications: electrical
External condition vehicle-mounted indicator or alarm
Highway information
C340S901000, C340S904000, C356S445000
Reexamination Certificate
active
06407674
ABSTRACT:
TECHNICAL FIELD
This invention relates to reflectivity measuring apparatus. More particularly, but not exclusively, this invention relates to a method and apparatus for assessing the integrity of road markers and markings.
BACKGROUND ART
Light reflective road markings and markers are extensively used to demarcate vehicle lanes and supply vital information to drivers about sections of road. They function by reflecting or retroreflecting light rays entering the reflective material of the road marking back to a driver. This is achieved, for example, by a vehicle's headlights beaming onto the road marking. Road markings include coloured lines of varying composition and markers such as raised pavement markers (RPM's). Maintaining the reflectivity of road markings is an important aspect of road safety.
Road markings, and in particular RPM's, are periodically tested to ensure they continue to meet minimum standards of reflectivity/retroreflectivity. Many road authorities stipulate a minimum acceptable reflectance value for an RPM. A conventional method of checking RPM's is by way of night time drivebys using headlights whereby personnel visually assess each RPM and tag any that appear to reflect a low level of light. RPM's can then be replaced at that time or replaced at a later date. Disadvantages with this method include being restricted to night-time testing; visual assessments are subjective and can vary between different tests and personnel which can result in erroneous results and the unnecessary replacement of RPM's; assessment conditions such as vehicle headlight strength and angles, speed, oncoming traffic and weather conditions can contribute to erroneous diagnoses; and auditing of personnel and their assessments can be difficult and subjective. These disadvantages can result in inefficient expenditure on road markings.
An alternative known method is to use a portable hand held measuring instrument. In this case, operators walk beside road markings and take measurements at spaced distances along a section of road. Disadvantages with this method include the amount of time required to cover sections of road and take measurements, road closure delays causing an inconvenience to motorists, a high cost to roading authorities, an unacceptable risk to users who are exposed to road traffic and pollution on sections of road such as motorways and tunnels.
In the case of RPM's, they are generally secured to the centreline or to lines separating lanes and have two highly reflective surfaces to reflect light from a vehicle's headlights back to its driver. The reflected light offers an aid to night time driving. As RPM's are generally devices made of a plastics material and raised above the road level, they deteriorate quickly due to repeated tyre abuse. Therefore, they require regular integrity checks and maintenance.
It is an object of the present invention to provide a method and apparatus for testing the integrity of road markings which overcomes at least some of the abovementioned problems, or which at least provides the public with a useful choice.
SUMMARY OF THE INVENTION
In a first broad aspect of the invention there is provided a reflectivity measuring apparatus for testing the integrity of road markings including a light source, a light sensor and a processing means, the apparatus being mounted on a vehicle such that, in use, the light source illuminates a reflective surface on a road marking, and wherein the light sensor detects any reflected light and the data signal is received by the processing means, the processing means processes the data to provide information on the reflectivity of a said reflective surface.
Preferably the apparatus further provides a locating means for determining the location of a road marking. Desirably the location means is a global positioning system or a vehicle gearbox revolution sensor.
Advantageously a plurality of light sensors are provided to cover a wide field of view, each said light sensor detecting any reflected light from a different area of road and providing a data signal to the processing means representing the reflectivity of each said area of road.
Preferably the apparatus further comprising an audio and/or visual means to provide an indication of the location of the said road markings relative to the vehicle.
Preferably a plurality of said light sources and a plurality of said light sensors provide simultaneous testing of a plurality of said road markings. Desirably the light source and the light sensor are adjustable. Preferably the light sensor is mounted in front of a corresponding said light source.
Desirably the processing means stores data measured on the reflectance level and location of each said road marking tested. Preferably a predetermined acceptable reflectance level for the road marking is obtained as a reference reflectance level against which each said road marker being tested is compared by the processing means. Preferably the processing means is a computer.
Desirably the apparatus further comprises a tagging means for identifying said road markings that do not meet the predetermined acceptable reflectance level. Preferably the tagging means includes a paint capsule dispenser activatable by the processing means.
Preferably the said road markings are raised pavement markers with at least one reflective surface.
In another aspect of the invention there is provided a computer controlled process for determining the integrity of reflective road markings, the computer being programmed to carry out the steps of:
a. getting data on the reflectance levels of road markings;
b. calibrating the data by multiplying the data with a predetermined calibration factor; and
c. determining whether the road marking meets a predetermined acceptable reflectance level.
Preferably the process further includes the step of filtering the data by calculating an average reflectance level from a set of sampled data.
Preferably the process further includes the step of getting data from a vehicle gearbox revolution sensor and determining the distance travelled from the start position of the road marking test so as to determine the location of each road marking.
Preferably the process further includes the step of activating a road marker tagging means to tag a road marker if it is determined as having a reflectivity level which does not meet the predetermined acceptable reflectance level.
Preferably the process further includes the step of storing on any suitable medium the location and reflectivity level of each road marker.
Preferably the process further includes the step of determining the location of any missing road markers by recognising patterns in existing road marker locations and with being provided with information on the spacing of known valid road markers.
Preferably the process further includes the further step of converting data to a format for presentation in either a graphical or numerical form, and be viewed in real time on a monitor or in printed form.
REFERENCES:
patent: 2750583 (1956-06-01), McCullough
patent: 4373819 (1983-02-01), Pallotta
patent: 4505590 (1985-03-01), Heenan
patent: 4721389 (1988-01-01), Dejaiffe
patent: 4856931 (1989-08-01), Bollag
patent: 5774070 (1998-06-01), Rendon
Swarthout Brent A.
Synnestvedt & Lechner LLP
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