Automated Traffic Measurement (Part - 1) - Civil Engineering (CE) PDF Download

Introduction 

This present paper offers a review on some of the latest automated traffic data collection technologies. This automated technology briefly summarizes as two methods. The first technology is in-situ technology and second one is in vehicle technology. Broadly speaking, “in-situ” technologies refer to traffic data measured by the means of detectors located along the roadside. Generally, traffic count technologies can be split into two categories: the intrusive and nonintrusive methods. The intrusive methods basically consist of a data recorder and a sensor placing on or in the road. Non-intrusive techniques are based on remote observations. Then the next order automated traffic data technology is floating car data (FCD). FCD is an alternative or rather complement source of high quality data to existing technologies. They will help improve safety, efficiency and reliability of the transportation system. They are becoming crucial in the development of new Intelligent Transportation Systems (ITS). Then finally discussed travel time prediction by these technologies.Introduction This present paper offers a review on some of the latest automated traffic data collection technologies. This automated technology briefly summarizes as two methods. The first technology is in-situ technology and second one is in vehicle technology. Broadly speaking, “in-situ” technologies refer to traffic data measured by the means of detectors located along the roadside. Generally, traffic count technologies can be split into two categories: the intrusive and nonintrusive methods. The intrusive methods basically consist of a data recorder and a sensor placing on or in the road. Non-intrusive techniques are based on remote observations. Then the next order automated traffic data technology is floating car data (FCD). FCD is an alternative or rather complement source of high quality data to existing technologies. They will help improve safety, efficiency and reliability of the transportation system. They are becoming crucial in the development of new Intelligent Transportation Systems (ITS). Then finally discussed travel time prediction by these technologies.

General 

The vehicular traffic is increasing tremendously in today’s/this world, simultaneously congestion also increases. In order to prevent congestion, one option is to increase the capacity by increasing the number of existing transportation system. A second option is to develop alternatives that increase capacity by improving the efficiency of the existing transportation system. The later focuses on building fewer lane-miles, while investing in Intelligent Transportation Systems (ITS) infrastructure. The goals of ITS include the following:
1. Enhance public safety;
2. Reduce congestion;
3. Improved access to travel and transit information;
4. Generate cost savings to motor carriers, transit operators, toll authorities, and government agencies; and
5. Reduce detrimental environmental impacts.

Intelligence requires information, and information requires data, which is generated by surveillance. ITS include sensor, communication, and traffic control technologies. These technologies assist states, cities, and towns nationwide, meeting the increasing demands on surface transportation system. Vehicle detection and surveillance technologies are an integral part of ITS, since they gather all or part of the data that is used in ITS. So a wide range of data is required for ITS to manage:
1. Volume Count
2. Vehicle Classification
3. Vehicle Occupancy
4. Travel Time
5. Delay

Volume Count 

Traffic volume studies are conducted to determine the number, movements, and classifications of roadway vehicles at a given location. These data helps to identify critical flow time periods, determining the influence of large vehicles or pedestrians on vehicular traffic flow. The length of sampling period depends on the type of count being taken and the intended use of recorded data. Two methods are available for conducting traffic volume counts: (1) manual and (2) automatic. Manual counts are typically used to gather data for determination of vehicle classification, turning movements, direction of travel, and vehicle occupancy.

Manual Count 

Method Most applications of manual counts require small samples of data at any given location. Manual counts are rarely used when the effort and expense of automated equipment are not justified. Manual counts are necessary when automated equipment is not available. Manual counts are typically used for period of less than a day. Normal intervals for a manual count are 5, 10, or 15 minutes. Traffic counts during a rush hour of Monday morning and Friday evening rush hours shows exceptionally high volumes and is not normally used in analysis; therefore, counts are usually conducted on Tuesday, Wednesday, or Thursday.

Automatic Count Method 

The automatic count method provides a means for gathering large amounts of traffic data. Automatic counts are usually taken in 1-hour interval for each 24-hour period. The counts extend for a week, month, or year. When the counts are recorded for each 24-hour time period, the peak flow period can be identified. Automatic counts are recorded using one of three methods: portable counters, permanent counters, and videotape

Vehicle Classification 

Traffic volumes vary over time on all roads. Traffic volumes also vary dramatically from one road to another. These variations in traffic volume are even more apparent when volumes for specific vehicle types (classification) are analyzed. Consequently, the vehicle classification data collection program must gather sufficient data on traffic patterns of important vehicle types to accurately quantify the truck traffic stream to meet the needs of users. These include; time of day, day of week, time of year, direction. Vehicle classification counts are used in establishing structural and geometric design criteria, computing expected highway user revenue, and computing capacity. If a high percentage of heavy trucks exist or if the vehicle mix at the crash site is suspected as contributing to the crash problem, then classification counts should be conducted. Typically cars, station wagons, pickup and panel trucks, and motorcycles are classified as passenger cars. The observer records the classification of vehicles and its direction of travel at the intersection.

Integration of Classification Count 

The vehicle classification counts required should not be considered separate from the volume counts traditionally performed. Instead, they should be integrated with the traditional volume counts. Because classification counts provide both classification and total volume information, they can replace traditional volume counts reducing duplication and error. Traffic surveillance equipment is used as part of advanced traffic management systems (ATMS) or advanced traveler information systems (ATIS) can be used to supply both total volume and vehicle classification information. Intelligent transportation system (ITS) technology and its resulting data are often present at high profile locations as part of safety enhancement systems. These systems can supply useful, continuous traffic monitoring data. Coordinating these traffic monitoring activities can lead to significant improvements in the amount of data available to users, while at the same time reducing the cost of data collection.