ML20235D756
| ML20235D756 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 07/23/1987 |
| From: | Hartgen D, Lemmerman J NEW YORK, STATE OF |
| To: | |
| References | |
| OL-3-S-001, OL-3-S-1, NUDOCS 8709250331 | |
| Download: ML20235D756 (5) | |
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% PLANNING DIVISION NEW YORK STATE DEPARTMENT'0F TRANSPORTATION w...
'87 SEP 17 A8:16 TRANSPORTATION ANALYSIS REPORT
- LOL, 19 DATE:
JANUARY 1983 AUTHORS:
David T. Hartgen John H. Lemmerman TITLE:
STREAMLINING THE COLLECTION AND PROCESSING OF TRAFTIC COUNT STATISTICS ABSTRACT: Traf fic volume counts provide basic information for transpor-tation analysis and forecasting, as well as facility design, monitoring, and operation. The traditional methods of or-ganizing a traffic count program have changed little since 1965.
Basically, they include a system of continuous counter stations for developing seasonal adjustment factors, seasonal-control stations to aid in factor development as well as in determining the seasonal assignment of coverage count stations, and the coverage count stations themselves.
Such a program works well but is quite costly.
Thus, the New York State Departrent of Transportation undertook to examine its program and procedures as well as look ahead at new tech-nology in order to streamline the process and reduce costs.
Seasonal adjustment factors for coverage counts were revised and the number of factor groups was reduced. The method of determining which sections should be counted was also revised and based upon changes in traffic volumes,'and telemetry sys-tems and methods of co11ceting additional traffic data (truck weight, vehicle classification) were. chamined.
Implementation of these improvements yielded a 35% re' duction' in counting with I
littic or no loss of information.
TRAVEL AND ENVIRONMENTAL STATISTICS TR ANSPORT ATION SYSTEMS INVENTORIES TRAVEL AND ENERGY FORECASTING URBAN AREA TRAVEL ANALYSIS l
New York State Department of Transportation William C. Hennessy, Commissioner Planning Dmsion State Campus Albany, New York 1223 2 TP 442 nie2>
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typically be~ applied to raw counts.
- Although FINA (1) provides 1
. standard formulas for the computation of such f actors, NYSDOT has not, traditionally, undertaken such corrections unless the percent is t
"large" (e.g. above. 20% multi-axle vehicles). However, recent concern for trucks as a factor in pavement-deterioration and highway capacity have increased attention on this subject.
Since multi-axle vehicle-
. proportions tend to vary widely by location and ' facility type,.and
'I reflect local conditions such as truck terminal centers,-considerable-research is needed to establish the nature of such variations. NYSDOT is presently undertaking this work.
In the interim, we continue to -
make adjustments when needed, but generally do not. undertake adjust -
ments for most counts.
Accuracy of Raw Counts L
l It is well known that various mechanical devices and manual counts will-q not always yield identical results. Differences in clock time, 1
q sensitivity of recording devices to vehicle pass-over, multi-axle vehicle proportions, and mechanical equipment fai1Me or malfunction all combine to introduce error.
i In August, 1981, a comparison of four separate counting methods (manual' l
counting ~, portable road-tube counters, a fixed mechanical continuous-
]
counter using induction loops, and a telephone-based counter system using the same induction loops) was conducted at a single location for a 24-hour period (19). Without elaborating on some of the details of the experiment and recognizing that there are hazards assocated with'
13 Hartgen and Lemmerman generalizations based upon the observations and situations encountered at one station of such short duration, it nevertheless appears appro-priate to suggest:
1.
There is no such thing as an accurate traffic count.
Clock error, machine error, percent trucks, and other factors are likely to cloud the reliability of any count.
2.
Manual counts are likely to contain considerable errors, particu-larly if conducted by inexperienced-or unsup.ervised personnel.
3.
When counts are taken with a road-tube counter, they will over-estimate traffic volume depending upon truck percentage.
Such counts should be adjusted for the multi-axle truck percentage, and checked closely for clock accuracy.
4.
Counts should be taken for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to minimize overall clock error.
Even over longer count periods, (1 day to 3 weeks),
counters are not likely to give similar results, but differences will be smaller.
5.
Both the continuous counter and the telemetry system show very-similar, but not exactly the same results.
I This test also showed that portable road-tube counters are reasonably l
1 accurate and can be relied upon to accomplish most of the Department's 1
traffic counting needs.
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M Hartgen and Lemmerman 15.
Federal Highway Administration, Evaluation of Vehicle Classification Equipment, United States Department of Transportation, September, 1982, s
16.
Francis, C.C., " Improved Methods for Vehicle Counting and Determining Vehicle Miles of Travel," Preliminary Technical Report in NCHRP Project CN-8-20, Hamburg and Associates, Bethesda, Maryland, 1981.
17.
Federal Highway Administration, Guide for Traffic Volume Counting Manual, United States Department of Transportation, March, 1970.
18.
New York State Department of Transportation, 1982 Traffic Volume Report, Planning Division, New York State Department of Transportation, l
Albany, New York, 1983.
]
I 19.
Snow, E.J., and J111 son, G., " Accuracy Cost and Responsiveness of j
Continuous Traffic Counting Systems:
A Report on the Burnt Hills I
(Glenville) Route 50 Telemetry Demonstration Project," Transportation i
Analysis Report No. 7, Planning Division, New York State Department of Transportation, Albany, New York, March 1982.
20.
- Neveu, A.J., " Quick-Response Procedures to Forecast Rural Traffic,"
Transportation Analysis Report No. 3, Planning Division, New York State Department of Transportation, Albany, New York, June, 1982.
21.
- Sharma, S.C., and Werner, A., " Improved Methods of Grouping Province-wide Permanent Traffic Cotnters," Record No. 815. Transportation Research Board, 1981.
22.
Dixon, W.J., Chief Editor, and Englemen, L., "P2M Cluster Analysis of Cases," BMDP Statistical Software, 1981 Edition, University of California Press, Berkeley, California, 1981.
23.
Walker, W.P., " Trends in the 30th-Hour Factor," Highway Research Board Bulletin 167:
Highway Capacity Studies, Washington, D.C., 1957.
24.
Bellis, W.R.,
and Jones, J.E., "30th Poak Hour Factor Trend," Highway Research Record 27:
Highway and Interchange Cape. cities, Washington, D.C.,
1963.
25.
Highway Research Board Special Report 87:
Highway Capacity Manaual, 1965,. Washington, D.C.,
1965.
26.
Oppenlander, J.C., " General Traffic Characteristics," Transportation j
and Traffic Engineering Handbook, Institute of Transportation l
Engineers, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1976.
I i
27.
Hatson, T.M., Smith, W.S., and Hurd, F.W., Traffic Engineering, l
l McGraw-Hill Book Company, Inc., New York, 1955.
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