17-07-2012, 01:10 PM
SPEED CHECKER ON HIGHWAY
SPEED CHECKER report.docx (Size: 504.21 KB / Downloads: 41)
INTRODUCTION
In response to a growing public concert) about incidents, crashes, congestion, and delay occurring on the Capital Beltway around Washington, D.C. (hereinafter called the Beltway), the Secretaries of Transportation in Maryland and Virginia, in cooperation with the senior leadership of the Federal Highway Administration (FHWA) and the National Highway Traffic Safety Administration (NHTSA), created an interstate task force in 1988 to
study the problems associated with the Beltway and recommend, test, and implement measures for remediation.
Description of the Beltway
The Beltway is a 64-mile-long limited-access highway encircling Washington, D.C. The majority of the Beltway, 41.6 miles, is in Maryland; a section of approximately one-tenth mile on the Woodrow Wilson Memorial Bridge is in Washington, D.C.
The Beltway was constructed in the late 1950's and early 1960's as a four- and six-lane facility to carry an estimated annual average daily traffic (AADT) of 40,000. In the 1960's and 1970's, most of the Beltway was widened to eight lanes because traffic growth was higher than originally assumed; however, there are still some six-lane sections. Increasing the number of lanesresulted in a significant reduction in shoulder width, mainly because of the limited right of way, thus making safe enforcement by mobile police patrols difficult and hazardous because traffic stops are made in close proximity to the high-olume travel lanes.
Operating Speeds on the Beltway
Speed data collected in 1990 for the Maryland and Virginia sections of the Beltway indicated that average nonpeak speeds ranged from approximately 58 mph to approximately 64 mph, dependingon the location. About 80 percent of the vehicles exceeded the 55 mph maximum speed limit, and about 40 percent exceeded 65 mph. The monitoring of 65,850 vehicles traveling in one direction during a 24-hour period in 1988 indicated that the average speed on the Beltway in Virginia was 64.6 mph. These Virginia data include speeds for rush-hour traffic, when traveling faster than the posted limit is generally not possible.
Time-Distance Method
The use of the first known method of speed enforcement dates back to 1902 in Westchester County, New York. This system was composed of three dummy tree trunks set up on the roadside at 1- mile intervals. A police officer with a stopwatch and a telephone was concealed in each trunk. As a speeding vehicle passed the first trunk, the hidden police officer telephoned the time to the second police officer, who recorded the time at which the vehicle passed
him and then computed its speed for the mile. If the vehicle was exceeding the speed limit, the officer telephoned the third police officer, who proceeded to stop the vehicle by lowering a pole across the road.