Traffic Volume Count is counting of a number of vehicles passing through a road over a period of time. It is usually expressed in terms of Passenger Car Unit (PCU) and measured to calculate the level of service of the road and related attributes like congestion, carrying capacity, volume count ratio, identification of peak hour or extended peak hour etc.
From the volume study hourly, daily, yearly and seasonal variation of vehicular flows are drawn. These variations are needed to establish expansion factors for future use. Using expansion factors, AADT can be calculated from the short count, flow fluctuations on different approaches at a junction or different parts of a road network system. AADT is needed with traffic growth rate to compute design wheel repetition. The geometric design is based on peak hour volume to avoid congestion.
The other purpose of traffic volume study estimates the travel demand when translated into vehicular and passenger flows. And estimation of highway usage.
Measurement of current demand of a facility, estimation of trends, economic feasibility, evaluation of accident rates etc.
RSM uses three methods to collect traffic volume for the required traffic information. They are:
The most common method of collecting traffic volume data is the manual method of traffic volume count which involves a group of people recording a number of vehicles passing, on a pre-determined location using tally mechanical counters. Raw data is then organized for compilation and analysis. This method of data collection can be expensive in terms of manpower, but it is nonetheless necessary in most cases where vehicles are to be classified with a few movements recorded separately.
Video Graphics Method
Video traffic surveys are a way to capture data in more complex situations such as busy roads and motorways. Video cameras will be placed in areas where we can capture the required information. This method is commonly recommended for being the most effective and accurate data collection tool as the captured footage can be fully backed up. From the video footage, volume counts & classification is drawn by manually in-office staff.
Automatic traffic counters (metro counts) are used to collect vehicle traffic data on roads. RSM collects data from one or two road tubes (rubber hose) stretched across the road. It can be used to collect data for traffic volume, vehicle classifications, and/or vehicle speeds. These counters are an excellent data collection tool, making a high-cost traffic survey and can be installed at very short notice.