2007 TRAFFIC DATA REPORT FOR NEW YORK STATE

New York State Department of Transportation

Table of Contents Page Chapter 1: Introduction .........................................................................................................1 Chapter 2: Traffic Data Collecting Program Overview........................................................2 Chapter 3: Accuracy of Traffic Data Section 3.1 Data Collection Equipment Requirements.............................................3 Section 3.2 Data Quality Control Checks .................................................................4 Chapter 4: Continuous Count Program Section 4.1 Introduction............................................................................................7 Section 4.2 Maps of Continuous Count Sites by Region..........................................8 Section 4.3 Map of High Speed Weigh-In-Motion Sites, Statewide .......................19 Section 4.4 Traffic Monitoring Site Details and Specifications ..............................20 Chapter 5: Coverage Count Program Section 5.1 Volume, Speed and Classification Counts............................................21 Section 5.2 Highway Performance Monitoring System ..........................................24 Section 5.3 Annual Traffic Monitoring Workshop..................................................24 Section 5.4 Mobile Traffic Monitoring Platforms ...................................................25 Section 5.5 County Counter Initiative .....................................................................26 Chapter 6: Adjustment Factors Section 6.1 Seasonal (Monthly) Adjustment Factors ..............................................27 Section 6.2 Axle Adjustment Factors ......................................................................28 Section 6.3 Example of Estimation of AADT .........................................................29 Section 6.4 Heavy Vehicle Percentages...................................................................32 Chapter 7: Traffic Data Viewer ...........................................................................................33 Chapter 8: Traffic Growth Forecasting and Estimation Techniques ...................................34 Appendix A: New York State Reference (900 Series) Routes Appendix B: New York Parkways by Jurisdiction Appendix C: AADT Values for Select Toll Facilities Appendix D: Map of NYSDOT Regions and County Codes Appendix E: Traffic Volume Report

Chapter 1 Introduction

Chapter 1 Introduction The Highway Data Services Bureau is responsible for collecting and reporting highway data in New York State. The authority for the bureau to take traffic counts on public highways throughout New York State is provided by the: Laws of New York State Book 24 (Highway Law) Part I Article II (Commissioner of Transportation) Section 10 (General powers and duties of the Commissioner relating to highways) Paragraph 13 - (“The commissioner of transportation shall:...) Compile statistics relating to the public highways throughout the state, and collect such information in regards thereto as he shall deem expedient.” This work is undertaken in cooperation with the United States Department of Transportation, local governments and other New York State departments and agencies. The United States Department of Transportation provides financial assistance for this activity. The NYSDOT Traffic Monitoring System complies with AASHTO Guidelines for Traffic Data Program (1992), FHWA Traffic Monitoring Guide (2001), and United State Code 23 CFR 500 B whose purpose is to “set forth requirements for development, establishment, implementation, and continued operation of a traffic monitoring system for highways and public transportation facilities and equipment (TMS) in each state.” Questions, comments and suggestions, contact: NYSDOT Highway Data Services Bureau Traffic Monitoring Section 50 Wolf Road, POD 3-2 Albany, New York 12232 (518) 457-1965 [email protected] Traffic data is available on the Highway Data Services Bureau’s web page : https://www.nysdot.gov/portal/page/portal/divisions/engineering/technical-services/highwaydata-services Copies of this report may be purchased for $10 from: NYSDOT Plan Sales Unit 50 Wolf Road Albany, NY 12232 (518) 457-2124

1

Chapter 2 Traffic Data Collection Program Overview

Chapter 2 Traffic Data Collection Program Overview The New York State Department of Transportation collects, summarizes and interprets information on the traffic traveling the State's highway system. The data is used to assess transportation needs and system performance as well as to develop highway planning and programming recommendations. Traffic data is also important for route planning and in the design of highway projects. Other government agencies and private businesses also employ this information. To collect this information, the Department operates two traffic monitoring systems: 1.

A Statewide Traffic Monitoring System currently consisting of 176 permanent continuous count stations that collect volume, speed, vehicle classification and truck weight data 24 hours per day, 365 days per year. These sites are located throughout the State to monitor overall traffic trends. Information from these counters is used to determine traffic growth and tendencies as well as develop pavement design input, seasonal adjustment factors used in determining estimates of annual average daily traffic (AADT) and directional design hour volumes (DDHV).

2.

A portable traffic counter program, also known as short counts, is comprised of inventory counts taken periodically on the State touring route system and special counts including mainline, ramp and approach counts for specific State projects. Approximately 8,000 counts of 2-7 days duration are taken annually. The State touring route system is divided into approximately 8,900 traffic control sections. As part of the inventory count program, each section is generally counted once every 3 years. The annual inventory program consists of 3,000+ counts obtained on the State touring route system and another 5,000+ counts taken for other purposes such as sampling of off system Federal Aid eligible and non-Federal Aid eligible local facilities, county roads, off system bridge counts, at-grade railroad crossing counts and other samples to support the Federal Highway Performance Monitoring System. Results are used to determine Vehicle Miles Traveled (VMT) and to develop growth factors for estimating current year counts from known prior year counts. Vehicle classification counts obtained at approximately 1,600 of the 8,000 count locations are used to develop NYSDOT regional axle adjustment factors. Individual vehicles are assigned to one of thirteen vehicle type categories established by the Federal Highway Administration (FHWA). Axle adjustment factors are computed for each highway functional classification category in each NYSDOT Region. Limited speed data is also collected during vehicle classification counts.

2

Chapter 3 Accuracy of Traffic Data

Chapter 3 Accuracy of Traffic Data Section 3.1 Data Collection Equipment Requirements Data collection equipment in use by NYSDOT and/or data collection contractors adheres to the following accuracy requirements: •

All portable traffic counters are tested annually, prior to the count season, to ensure that the count deviation does not exceed 2% from the average of the counters tested.

•

The average error in the speed of vehicles recorded is 2 km/h (1 mph) or less. Compliance is determined through simultaneous measurement of individual vehicle speeds using radar or previously tested equipment.

•

Vehicle type classification errors may not exceed 10% of the actual volume in any classification study conducted in a multi lane configuration. Vehicle type classification errors may not exceed 5% of the actual volume in any classification study conducted in a single lane configuration.

•

When there are fewer than one hundred (100) vehicles in a class, an error equal to the square root of the actual number of vehicles is deemed acceptable. Errors are computed based upon the sum of the absolute differences between the recorded and true volumes in each classification. The true value of each classification is determined by simultaneous manual observation for a period of one hour.

•

A Weight In Motion (WIM) Automatic Continuous Traffic Recorder (ATR) weighs and classifies vehicles and/or vehicle combinations having up to thirteen (13) axles using the input from Class I piezoelectric axle sensors and determines the weight of each axle and the speed of the vehicle in accordance with ASTM standard E1318-02; TYPE I: Tolerance for 95% probability of conformity: Wheel Load ±25% Axle Load ±20% Axle Group Load ±15% Gross Vehicle Weight ±10% Speed ±2 km/h (± 1 mph) Axle Spacing ±150 mm (± 0.5 ft.)

3

Chapter 3 Accuracy of Traffic Data

Section 3.2 Data Quality Control Checks The following are typical checks performed by traffic monitoring personnel in the review and editing of traffic data, using either a manual procedure or the automatic checks set in the NYSDOT Traffic Count Editor (TCE), and polling (telemetry) software. If the checks reveal data that is suspect, further investigation must be conducted to determine if the data is faulty and what course of action is mandated; i.e. deletion of a bad interval, repair of faulty equipment or discard the entire count. All Count Types All lanes and directions for one station must be processed, edited and submitted at the same time. Counts should contain distinct AM and PM peaks that can be easily verified graphically. Peak hour zero search – Typically there should be no hourly intervals with zero vehicles during the AM peak (6:00 to 9:00) and the PM peak (3:00 to 7:00). Volume zero period check –Adjusted using the TCE Condition Editor and polling software to establish a time range where zero intervals are identified. Volume range check - Adjusted using the TCE Condition Editor and polling software to establish acceptable data ranges per interval with minimum and maximum values. Midnight/noon comparison – Comparison of midnight and noon volumes to ensure that the times of collection are correctly offset 12 hours by confirming that the noon interval value is greater than the midnight interval value. Volume flat period check – Compare adjacent intervals to identify a ‘flat’ period of no change in volume indicating a possible equipment error. Volume directional split check – Compare intervals in bi-directional count to identify intervals in excess of an operator defined ratio. TCE and the current polling software uses a 2:1 ratio (66%/33% split) as a default to identify intervals that may be in error with an excessively high volume in one direction and an unusually low volume in the opposite direction. •

Possible error: An interval contains 1345 vehicles in easterly direction and 202 vehicles in the westerly direction; an 87% / 13% split which should be investigated to determine if the comparatively low volume in the westerly direction is unusual and invalid.

Volume percent range – Identify intervals that deviate by 50% or more from the hourly interval average for the count. A minimum volume can be established in the TCE Condition Editor. Typically this check is effective for intervals with greater than 100 vehicles.

4

Chapter 3 Accuracy of Traffic Data

Classification Data Please note: In hourly intervals with less than 100 vehicles, the following conditions generally do not apply. Class F2 versus F3 – Compare class F2 (short wheelbase two axle passenger vehicles) to class F3 (longer wheelbase two axle pickups and vans). Typically, F2 vehicle bins are greater than F3 vehicle bins. •

Possible exception: In some rural areas a high F3 count due to a large percentage of pickup trucks will cause an F3 count to be the same order of magnitude as an F2 count.

Class F8 versus F9 – Compare class F8 (large four axle truck w/ trailer combination) to class F9 (heavy five axle truck w/trailer combination, the “18 wheeler”). Typically, F9 vehicle bins are greater than F8 vehicle bins. Class F9 versus F11+F12+F13 - Compare class F9 to the sum of the vehicles in bins F11, F12 and F13 (heavy truck w/ multi-trailer combination). Typically, F9 vehicle bins are greater than the sum of F11, F12 and F13 vehicle bins. •

Possible error: High number of F11, F12 or F13 on non-interstate routes. This is rare.

Class F1 – Intervals that contain a high F1 bin (motorcycles) should be investigated to determine if an unusual event resulted in a large number of motorcycles to cross this segment or if equipment error is the possible cause. •

Possible error: Typically a high F1 count is the result of an F9 being interpreted by the ATR as an F6 (three axle single unit truck) being followed by an F1. In this case, there are errors in three bin types, F1, F6 and F9.

Speed Data Typically a good speed count contains a normal distribution curve through speed bins in an interval. The bin containing the greatest number of counts is typically coincidental (‘center mass’) with the speed limit at the count location. There should be a uniform cluster (i.e. the distribution should remain relatively constant) throughout all intervals in a 24 hour period. •

Possible error: Major shift of the distribution curve, average speed and 85th percentile speed to lower speed bins in an interval which may be indicative of an accident or some other incident causing a slow down of traffic.

85th percentile check - Identify intervals where the 85th percentile speed deviates by 20% or more from the hourly interval average 85th percentile speed for the count.

5

Chapter 3 Accuracy of Traffic Data

Weigh-In-Motion Data Front Axle Weight - The typical front steering axle weight of a class F9 five axle ‘tractor-trailer’ combination should not be less than 9000 pounds or greater than 12000 pounds. The polling software reports a possible error if more than 10% of the F9 steering axles are outside this range for a one day (24 hour) period. If a possible error is reported, an auto-calibration problem or piezoelectric axle sensor failure at a particular Weigh-In Motion (WIM) site collecting truck weight data may exist and should be checked by maintenance personnel. Drive Axle Spacing - The typical drive axle spacing of a class F9 five axle ‘tractor-trailer’ combination should not be less than 4.0 feet or greater than 4.5 feet. The polling software reports a possible error if more than 10% of the F9 drive axles are outside this range for a one day (24 hour) period. Possible error: If a possible error is reported, an incorrect sensor spacing problem or piezoelectric axle sensor failure at a particular WIM site may exist and should be checked by maintenance personnel.

6

Chapter 4 Continuous Count Program

Chapter 4 Continuous Count Program Section 4.1 Introduction The Traffic Monitoring Section of the New York State Department of Transportation operates a Statewide Traffic Monitoring System consisting of approximately 176 permanent continuous count stations that collect volume, speed, vehicle classification and truck weight data 24 hours per day, 365 days per year. Information from these counters is used to determine traffic growth and trends as well as develop seasonal adjustment factors used in determining estimates of annual average daily traffic (AADT) and directional design hour volumes (DDHV).

The sites utilize a variety of sensors and arrays to collect data including inductive loops, piezoelectric axle sensors, and non-intrusive acoustic sensors.

To request continuous count data, contact: NYSDOT – Highway Data Service Bureau (518) 457-1965 [email protected]

7

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

Section 4.2 Maps

8

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

9

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

10

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

11

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

12

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

13

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

14

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

15

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

16

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

17

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

18

Chapter 4 Continuous Count Program Active Continuous Count Stations for 2007

19

Chapter 4 Continuous Count Program

Section 4.3 Traffic Monitoring Site Details and Specifications The Traffic Monitoring Section is responsible for the contents of NYSDOT Engineering Bulletin 00-056, “Traffic Monitoring Site Details, Specifications and Guidance Manual”. It provides guidance and recommended installation details for traffic monitoring sites. The detail sheets and specifications provide program managers with the basic drawings and guidelines necessary for the project planning process. The identification of an appropriate capital project candidate for a traffic monitoring site should entail a joint effort of Planning and Design during Project Design Phase IV. The drawings are maintained and available electronically via the NYSDOT CADD Standard Cell Library. In addition to the typical site installation items found in the NYSDOT Standard Specification, the following specifications are compiled by the Traffic Monitoring Section and copies are available by request: Furnish & install tri-mode CDMA, PCS and analog cellular wireless modem Furnish & install digital data pager Furnish & install low power modem (land line) Furnish & install Automatic Traffic Recorder w/ 8 loop inputs Furnish & install Automatic Traffic Recorder w/ 8 loop & 8 piezo inputs Furnish & install WIM Automatic Traffic Recorder w/ 8 loop & 8 piezo inputs Furnish & install 50 watt solar panel with angled mounting support structure Furnish & install solar charge controller Furnish & install traffic monitoring cabinet pole Install non-intrusive sensor equipped traffic monitoring site Furnish & install 100 Ah deep cycle gel cell battery

20

Chapter 5 Coverage Count Program

Chapter 5 Coverage Count Program Section 5.1 Volume, Speed and Classification Counts Coverage or short counts are taken at approximately 8,000 – 10,000 locations throughout the state on many geographically diverse facilities. Daily averages from the short counts, also known as ADT Average Daily Traffic, are converted to AADT used to compute highway VMT for use in financial and capital program planning, for reports to FHWA on highway use, as input to congestion management and air quality studies, and for project planning where design features are determined by the volume of traffic. The volume data is often supplemented with vehicle classification, weight, and/or speed information. The duration and frequency of NYSDOT’s TMS complies with the data needs identified in 23 CFR 500.203(a). The NYSDOT Highway Data Services Bureau’s (HDSB) Engineering Instruction (EI) 01-001 establishes the traffic monitoring standards for all of New York State’s short count Traffic Monitoring Activities (TMA) undertaken through contractual agreements for planning and/or project development. EI 01-001 ensures that the raw data from traffic monitoring activities undertaken pursuant to, or as part of, any contractual agreements involving funds administered and/or provided by NYS is in conformance with NYS standards established for traffic count data collected on Federal, State and selected local roadways and that it reaches the inventory data files maintained by the NYSDOT Highway Data Service Bureau in the appropriate data format. These standards apply to all TMA undertaken by private consulting engineering firms and other non-NYSDOT organizations, in support of any project or study for which funds administered or provided by NYS have been or will be used. EI 01-001 establishes that the traffic count locations are identified by a NYSDOT region/county code and a unique four digit traffic station number reference. These reference numbers are provided by the Regional Planning Office or the Highway Data Services Bureau, Albany, New York. Collection standards are set forth by EI 01-001. Criterion of the coverage count program includes the use of, at a minimum, 48-hour short counts to produce AADTs with a confidence level of 95% within an interval of ±10% of the mean statistic. The devices used to monitor traffic accurately measure existing traffic. Additionally, device type, model accuracy, precision documentation, and operation and maintenance records are maintained by a contractor or state personnel and provided to NYSDOT before the beginning of each count season. Standards defined in EI 01-001 apply to volume, classification, length and speed counts: *

All counts taken in urban areas must have a data recording interval of 15 minutes. Use of recording intervals other than 15 minutes requires written approval from the Regional Planning Office.

*

All counts taken in rural areas have a data recording interval of one hour. NYSDOT reserves the right to request a data recording interval of 15 minutes. 21

However

Chapter 5 Coverage Count Program

* A minimum of 48-hours of data are reported from each coverage or special count site, with at least 2 complete counts for each interval. *

All counts are taken by direction unless this is not feasible.

*

The entire 48-hour count must fall within the work week (06:00 a.m. Monday through 12:00 noon Friday). Weekend data is not used by NYSDOT for estimating AADT.

*

No part of the 48-hour count used for AADT estimation may contain data collected within 36-hours before and after any major weekday holiday or extended weekend formed by a Federal, State, or Local holiday.

*

All counts are adjusted for seasonality and, if taken with road tubes, for vehicle axles.

Vehicle occupancy counts are project specific and available upon request from regional planning offices or Metropolitan Planning Organizations. Vehicle classification data is the basis for estimating annual travel by each type of truck, ton miles of cargo hauled over highways, and changes in axle and gross weight frequencies on the highways. Vehicle classification and speed data are also used in the development of transportation policy, and allocation of highway costs and revenues, the regulation of size and weight, the establishment of geometric design criteria related to size and weight of vehicles, the study of pavement and bridge deterioration, and for various special studies. NYSDOT uses FHWA’s “F-Scheme” to classify vehicle types. The classification scheme is separated into categories depending on whether the vehicle carries passengers or commodities. Number of axles and number of units, including both power and trailer units, further subdivide non-passenger vehicles. A vehicle towing a light trailer does not change its classification. Refer to figure 1 for examples of FHWA Vehicle Classifications. Conduct of vehicle classification counts are regulated by EI 01-001. These counts are conducted for a minimum 48-hour period by direction and by lane during the work week (06:00 a.m. Monday to 11:59 am Friday). Free flow conditions are required for effective machine classification. Where conditions are not free flow or speeds are lower than 25 mph, manual vehicle classification counts (see below) are obtained instead. Classification devices currently in use accurately record axle impulses, but do not provide consistent and accurate interpretation of axle impulses into classification of vehicles when vehicles (typically in urban areas) are traveling at speeds below 25 mph. Manual classification counts are based on FHWA F-Scheme specified vehicle classification categories. This count activity uses the following guidelines to collect classification data when vehicle speed is restricted. •

Manual vehicle classification counts are taken by lane and direction. Twenty four (24) hour counts are taken within the NYSDOT work week (6:00 a.m. Monday through 11:59 am Friday). The 24 hour count period begins at 6:00 a.m. to capture the entire morning peak traffic at the location. A concurrent volume count is scheduled at the classification 22

Chapter 5 Coverage Count Program

location according to the Department=s standard. The volume count includes the manual class count hours of operation. Manual class counts for other than 24 hour duration may be requested for special projects. Manual volume and/or classification counts are employed for intersection turning movement counts. In accordance with EI 01-001, a GPS reading must be collected for all volume and classification counts (including manual counts). The GPS position of the traffic count has an accuracy of at least 12 meters and is provided on the North American Datum of 1983 (NAD83), Universal Transverse Mercator (UTM) coordinate system Zone 18, North, in meters.

FHWA VEHICLE CLASSIFICATIONS 1

5

Motorcycles

Two Axle, 6 Tire Single Units

2

Passenger Cars

3

Two Axle, 4 Tire Single Units

4

6

Three Axle Single Units

7

Four or More Axle Single Units

8

9

Five Axle Single Trailers

10

Six or More Axle Single Trailers

12

Six Axle Multi- Trailers

13

Seven or More Axle Multi- Trailers

Figure 1

23

11

Buses

Four or Less Axle Single Trailers

Five or Less Axle Multi-Trailers

Chapter 5 Coverage Count Program

Section 5.2 Highway Performance Monitoring System The Federal Highway Administration (FHWA) has the responsibility to assure that adequate highway transportation information is available to support its functions and responsibilities, including that of reporting to the US Congress. The primary purpose of the Highway Performance Monitoring System (HPMS) is to serve these data and information needs. The HPMS provides data that reflects the extent, condition, performance, use and operating characteristics of the nation’s highways. The HPMS is a nationwide inventory system that includes data for all of the Nation’s public road mileage and certified by the States’ Governors on an annual basis. This includes facilities both on and off the state highway system. The provision of HPMS data is a cooperative effort with state highway agencies (SHAs), local governments and metropolitan planning organizations (MPOs) working in partnership to collect, assemble, and report the necessary information. NYSDOT is an active HPMS partner. The data collected by HPMS is provided to the US Congress by the FHWA and serves as vital input to the federal aid apportionment formulas. The HPMS data is also used to monitor vehiclemiles of travel (VMT) for input to air quality monitoring under the Clean Air Act. The annual HPMS update contains summary data from inventories of the state and local highway systems plus more detailed field inventories of approximately 2700 samples statewide. Included in the information collected is data on pavement condition and highway use (traffic count and classification data). The resulting file is submitted to the FHWA once a year and provides a comprehensive picture of the extent, condition, and usage of the public roadway system in New York State. More detailed information about NYSDOT’s HPMS program can be provided by HDSB’s Highway Data Section.

Section 5.3 Annual Traffic Monitoring Workshop The Traffic Monitoring Section conducts an annual Traffic Monitoring Workshop at the beginning of each calendar year. The Workshop is held at a location that is central to the NYSDOT Regions. Attendees include NYSDOT personnel and contractors responsible for collecting, processing and analyzing New York State traffic data, as well as representatives from MPOs, New York State authorities, counties and municipalities, DOTs from adjacent states, and equipment and software vendors. The Workshop enables a peer exchange to discuss new technology, techniques and tools available to the traffic monitoring community, identify and resolve contractual and scheduling issues prior to a data collection season, and to conduct mandatory safety training. The Workshop is open to anyone responsible for the safe and effective collection of traffic data.

24

Chapter 5 Coverage Count Program

Section 5.4 Mobile Traffic Monitoring Platforms The mobile traffic monitoring platform was developed in house by NYSDOT personnel to support non-intrusive sensor technology with applications in data collection and Intelligent Transportation System (ITS) activities. Safety was the conceptual priority. Use of this platform greatly reduces personnel exposure to traffic, but still meets the needs of the Department. Six Mobile Traffic Monitoring Platforms have been built to date. Each is used to collect volume data on high speed, high volume multi-lane facilities where typical collection methods cannot be used to due safety concerns or equipment limitations. They have also been used to collect data on snowmobile and all terrain vehicle (ATV) recreational routes, railroad traffic at roadway at-grade crossings, and at special events such as the annual New York State Fair. Each platform supports a Smartek SAS-1 passive acoustic sensor which can be erected outside the traveled way and operational in approximately 30 minutes. Smartek software fully integrates with the NYSDOT Traffic Monitoring System and easily converts collected data from proprietary formats to the volume (.vol) file format required by NYSDOT Engineering Instruction 01-001, ATraffic Monitoring Standards@. These platforms greatly reduce the dangers associated with gathering traffic data by keeping technicians out of the traffic stream versus placing conventional tubes and counters in traffic on the above mentioned facilities. The mobile sensors may be employed year round in most locations, and are also much more cost effective than building multi-lane loop sites to take one rotational three day count every three years. Use of these platforms to satisfy data collection activities where traditional methods cannot be safely employed may be scheduled by contacting: Traffic Monitoring Section (518) 475-1965 [email protected]

25

Chapter 5 Coverage Count Program

Section 5.5 County Counter Initiative This program provides NYSDOT-compatible traffic counters and software support to County or highway departments in order to foster the sharing of resources between the Counties and the State in the area of traffic monitoring. This is accomplished through the purchase of a sufficient number of counters for Apermanent loan@ to Counties interested in participating and an agreement to provide appropriate training in and support of their use. In return, the Counties agree to adjust their count programs to meet State standards and needs as well as their own and to submit traffic data collected on their facilities to NYSDOT annually. The purpose of this initiative is to eliminate this duplication of effort and, in the process, enrich the data set available to both the State and the Counties. Federal funding allocations to each State are dependent, in part, on the amount of travel occurring on the entire Federal Aid System, including those highways not owned by the State. Traffic data is also required for all of the bridges in the State, approximately 6,000 of which are owned by the Counties. Many of the Counties in New York State already have a traffic counting program at some level to support decision making with regard to the county highways and bridges. Since their equipment and processing routines are incompatible with those of NYSDOT, the State and Counties often end up doing duplicative work so each can collect the data in the format with which they are accustomed. The benefit to the State is a reduction in the need for resources (staff or contractual) to collect data on the highways and bridges owned by the Counties and an increase in the amount of Federal Aid System data available with respect to the county systems. The benefit to the Counties is the availability of state-of-the-art equipment, software, and training at the cost of making some adjustments to their scheduling and processing routines. Additional benefits is ongoing software support and upgrades from the State, the merging of their data in a compatible format with a much larger data base which would be made available to them, the storage and maintenance of their historical and current count data by the State, the provision of appropriate seasonal and other adjustment factors for their counts, and other analytical reports routinely prepared from the State data. Any New York State Counties or highway departments interested in participating in this program please contact: Traffic Monitoring Section (518) 475-1965 [email protected]

26

Chapter 6 Adjustment Factors

Chapter 6 Adjustment Factors Section 6.1 Seasonal (Monthly) Adjustment Factors Traffic is typically affected by the seasons of the year with it being low during the winter months and high during the summer months. Seasonal Adjustment Factors are used to remove this seasonal bias by converting the Average Daily Traffic (ADT) from short count data into Annual Average Daily Traffic AADT. AADT is the average daily traffic for the entire year. The main objective of the continuous count program is for developing Seasonal Adjustment Factors as stated in the TMG*. The Seasonal Adjustment Factors are calculated using the average of three years of continuous count volume data. The factors are grouped into three major groups according to how much the road segments are affected by the seasons of the year. These factor groups follow the suggestions of the TMG.† The categories are labelled: Factor Group 30 urban traffic patterns minimally affected by the seasons coefficient of variation < 10% Factor Group 40 suburban traffic patterns moderately affected by the seasons coefficient of variation >= 10% and < =25% Factor Group 60 recreational traffic patterns extremely affected by the seasons coefficient of variation > 25% Minor factor groups surround the major factor groups and are labelled +/-1 of the major factor group label. For instance, Factor Group 30 would have minor factor groups of 29 and 31. These minor factor groups are supplied to give the user a more fine-tuned calculation of the AADT. The Seasonal Adjustment Factors abide by the recommendation of the TMG: The reliability levels recommended are 10 percent precision with 95 percent confidence, 95-10, for each individual seasonal group, excluding recreation groups where no precision requirements is specified.‡ Figure 5 on the following page displays a table of Seasonal Adjustment Factors used for converting short count weekday ADT for 2008 into an AADT. Other Seasonal Adjustment Factor tables are located on the Highway Data Services Bureau webpage: https://www.nysdot.gov/portal/page/portal/divisions/engineering/technical-services/highway-data-services

To calculate an AADT for a short term or coverage count using a Seasonal Adjustment Factor, refer to section 6.3, “Example of Estimation of AADT”.

*

FHWA Traffic Monitoring Guide – 2001 pg. 3-25 FHWA Traffic Monitoring Guide – 2001 pg. 3-33 ‡ FHWA Traffic Monitoring Guide – 2001 pg. 3-34 †

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Chapter 6 Adjustment Factors

Figure 5 SEASONAL ADJUSTMENT FACTORS FOR 2008 TRAFFIC COUNT PROCESSING (Based on 2005 - 2007 Continuous Count Site Data) WORK WEEK FACTOR GROUP 29

JAN 0.909

FEB 0.926

MAR 0.962

APR 1.002

MAY 1.042

JUN 1.071

JUL 1.056

AUG 1.056

SEP 1.023

OCT 1.027

NOV 0.990

DEC 0.952

30

0.961

0.975

1.018

1.051

1.089

1.123

1.094

1.103

1.072

1.075

1.031

0.999

31

1.019

1.029

1.081

1.106

1.141

1.180

1.136

1.156

1.127

1.129

1.076

1.052

39

0.769

0.783

0.828

0.888

0.992

1.058

1.121

1.125

1.000

0.965

0.886

0.827

40

0.829

0.843

0.888

0.950

1.049

1.111

1.191

1.188

1.054

1.015

0.940

0.885

41

0.900

0.914

0.958

1.021

1.112

1.171

1.272

1.258

1.114

1.071

1.002

0.952

59

0.617

0.627

0.643

0.670

0.904

1.072

1.329

1.305

1.006

0.862

0.710

0.650

60

0.685

0.700

0.730

0.782

1.000

1.159

1.488

1.446

1.072

0.934

0.793

0.720

61

0.770

0.791

0.844

0.939

1.119

1.260

1.690

1.621

1.147

1.020

0.896

0.808

FACTOR GROUP 30 40 60 minor factor groups

urban traffic patterns traffic is minimally affected by the seasons suburban traffic patterns traffic is moderately affected by the seasons recreational traffic patterns traffic is extremely affected by the seasons +/-1 of major factor groups used for minor adjustments

.

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Chapter 6 Adjustment Factors

Section 6.2 Axle Adjustment Factors AADT values in this publication represent vehicles. The axle adjustment factor is applied to traffic counts taken with pneumatic tube counters which register two axle impacts as one vehicle. It is used to account for vehicles with more than two axles, typically trucks with three or more axles, in the traffic stream on a particular type of road. The axle adjustment factors are developed from NYSDOT vehicle classification data collected over a six year period in eleven Regions and twelve functional classification categories of highway. The ADT is multiplied by the axle adjustment factor to obtain the AADT. Counts obtained with presence detectors such as inductive loops or acoustic sensors are not adjusted by this factor. Refer to table 1 below for the axle adjustment factors which are also available on the Highway Data Services Bureau webpage: https://www.nysdot.gov/portal/page/portal/divisions/engineering/technical-services/highway-data-services

To calculate an AADT for a short term or coverage count using an Axle Adjustment Factor, refer to section 6.3, “Example of Estimation of AADT”. AXLE ADJUSTMENT FACTORS FOR 2008 TRAFFIC COUNT PROCESSING BASED ON 2002-2007 VEHICLE CLASSIFICATION DATA REGION FC

1

2

3

4

5

6

7

8

9

10

11

STATEWIDE

RURAL 01

0.767

0.794

0.778

0.786

0.735

0.731

0.797

0.778

02

0.910

0.944

0.944

0.887

0.921

0.891

0.904

0.958

0.909

0.919

06

0.955

0.953

0.947

0.958

0.939

0.952

0.949

0.956

0.960

0.952

07

0.972

0.968

0.955

0.957

0.956

0.965

0.931

0.971

0.971

0.961

08

0.981

0.979

0.977

0.980

0.985

0.980

0.977

0.980

0.986

0.980

09

0.979

0.970

0.979

0.979

0.984

0.979

0.979

0.989

0.979

02

0.927

0.963

0.933

0.923

0.929

0.905

0.912

0.969

0.935

0.874

0.826

0.874

0.874

0.923

0.874

0.970

0.947

0.984

0.959

0.959 0.967

URBAN 11

0.923

0.874

0.874

0.874

0.870

0.874

12

0.974

0.962

0.954

0.983

0.974

0.833

14

0.964

0.973

0.971

0.969

0.969

0.959

0.954

0.978

0.941

0.972

0.983

16

0.976

0.972

0.980

0.980

0.972

0.976

0.973

0.982

0.977

0.982

0.984

0.984

17

0.984

0.980

0.987

0.987

0.986

0.988

0.978

0.985

0.990

0.981

0.992

0.985

19

0.987

0.987

0.987

0.987

0.985

0.987

0.987

0.987

0.986

0.987

0.987

0.987

ALL URBAN

0.968

0.958

0.959

0.963

0.959

0.936

0.953

0.955

0.953

0.963

0.971

0.959

ALL FC

0.948

0.960

0.946

0.943

0.944

0.920

0.933

0.962

0.944

0.963

0.971

0.959

Yellow shading indicates there are no highway segments in this FC in this Region Orange shading indicates that the statewide average for this FC was used or insufficient data (