Guidebook on Pedestrian and Bicycle Volume Data Collection (2014) / Chapter Skim
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Pages 75-99
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75 c h a p t e r 5 This chapter summarizes existing and emerging sensor technologies available for nonmotorized counting. Many of the technologies were developed for motor vehicle counting but have been adapted for non-motorized travel.
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From page 76... ...
76 Guidebook on pedestrian and Bicycle Volume Data collection • Strengths and limitations of the technology or method, drawing from the literature and the research team's experience. • Accuracy, drawing from the NCHRP Project 07-19 testing when possible, and supplementing from the available literature.
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Sensor technology toolbox 77 volunteers. Hand-written data sheets, if used, must be gathered, compiled, and reduced into a spreadsheet, which can be time-intensive.
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78 Guidebook on pedestrian and Bicycle Volume Data collection 5.1.7 Usage The NCHRP Project 07-19 practitioner survey found that manual counts are the most prevalent approach in the United States for collecting non-motorized volumes. Of respondents who performed counts, 93% included manual counts as part of their pedestrian data collection program and 87% included them as part of their bicycle data collection program.
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Sensor technology toolbox 79 5.2.3 Installation Considerations Video cameras should be installed high enough above the street (e.g., 10+ feet) to deter theft.
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80 Guidebook on pedestrian and Bicycle Volume Data collection 5.2.7 Usage The NCHRP Project 07-19 practitioner survey found that 44% of respondents who performed pedestrian counts used manual counts from video data as part of their pedestrian data collection program. (The question was not asked in conjunction with bicycle data collection; however, given the similar pedestrian and bicycle counting responses for other counting methods and technologies, the proportion would be expected to be similar.)
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Sensor technology toolbox 81 of a certain size (e.g., out to 150 feet)
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82 Guidebook on pedestrian and Bicycle Volume Data collection can be applied to the pattern of axle hits to determine the vehicle speed and classification. This process can either occur in real time or on a personal computer after the data have been recorded.
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Sensor technology toolbox 83 Follow the manufacturer's instructions on spacing and settings. If GPCs are being used, the settings need to be modified to apply a classification scheme to sort vehicles and isolate bicycle data.
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84 Guidebook on pedestrian and Bicycle Volume Data collection scheme was developed through the study to account for the systematic undercounting observed with the GPCs. Using this classification scheme, the GPCs proved accurate when bicyclists rode close to the counter, with an average accuracy of 95%.
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Sensor technology toolbox 85 5.5.3 Installation Considerations Select a mid-segment, channelized location where bicyclists are unlikely to stop and will be more likely to ride single file. Locations where loops can cover all (or nearly all)
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86 Guidebook on pedestrian and Bicycle Volume Data collection 5.5.5 Strengths and Limitations Strengths • Most jurisdictions are familiar with embedded loop technology, because it is also used to detect vehicles at traffic signals. • Can be used for on-street bicycle facilities.
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Sensor technology toolbox 87 -10% to +4% for on-road count sites and -10% to +25% for off-road sites (ViaStrada, 2009)
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88 Guidebook on pedestrian and Bicycle Volume Data collection 5.6.5 Strengths and Limitations Strengths • Small, portable, and easy to install. • Battery powered.
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Sensor technology toolbox 89 5.6.7 Usage Passive IR counters have been tested in research projects and are commercially available. These sensors are one of the primary automated technologies in practice in the United States for pedestrian counts.
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90 Guidebook on pedestrian and Bicycle Volume Data collection 5.7.4 Level of Effort and Cost The level of effort is medium relative to other technologies and requires setting up the emitter and the receiver in appropriate locations. The cost of the equipment is high, relative to other technologies, although overall installation costs are medium, relative to other technologies.
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Sensor technology toolbox 91 5.7.7 Usage Of those practitioner survey respondents who performed counts, 13% used active IR counters as part of their pedestrian counting program and 10% used them as part of their bicycle counting program. 5.8 Piezoelectric Strips 5.8.1 Description Piezoelectric materials emit an electric signal when they are physically deformed.
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92 Guidebook on pedestrian and Bicycle Volume Data collection 5.8.5 Strengths and Limitations Strengths • Provides speed and directionality data. • Discrete and not susceptible to tampering when embedded in pavement.
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Sensor technology toolbox 93 is detected. Devices that use multiple radio frequencies can differentiate between pedestrians and bicyclists.
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94 Guidebook on Pedestrian and Bicycle Volume Data Collection 5.9.6 Accuracy NCHRP Project 07-19 tested two radio beam products. Product A counted pedestrians and bicyclists separately, using two radio frequencies, while Product B counted a combined total of pedestrians and bicyclists using a single radio frequency.
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Sensor technology toolbox 95 The researchers faced significant difficulties evaluating the accuracy of the radio beam sensors because of a specific detail of the products being tested: namely, the counters defaulted to beginning a count immediately when initiated, rather than aggregating into bins beginning on the hour. This setting could be altered in an "advanced settings" menu, but most of the installers did not realize this.
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From page 96... ...
96 Guidebook on pedestrian and Bicycle Volume Data collection 5.11 Laser Scanners 5.11.1 Description Laser scanners emit laser pulses in a range of directions and analyze the reflections of the pulses to determine characteristics of the device's surroundings, including the presence of pedestrians or bicyclists. Two varieties of laser scanners exist: horizontal and vertical.
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Sensor technology toolbox 97 are used on mixed pedestrian and bicyclist facilities, the software in the sensor can distinguish the pressure from bicyclists separate from pedestrians. These devices are most commonly used on unpaved multi-use paths and off-road trails where they can be buried and concealed.
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From page 98... ...
98 Guidebook on pedestrian and Bicycle Volume Data collection 5.13 Magnetometers 5.13.1 Description Magnetometers detect bicycle activity through changes in the normal magnetic field as a bicycle's metal parts pass by. Magnetometers are more commonly used as part of vehicle detection systems to detect the presence and movement of vehicles.
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Sensor technology toolbox 99 be counted. A European vendor states that the technology can be used on mixed-traffic roadways to count bicycles separately from motor vehicles.
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