CDTC Traffic Volume Report Data Description

Introduction

The data contained in the Traffic Volume Report is based almost exclusively on the results of existing traffic inventory efforts and is intended to provide a reasonable representation of the traffic flow patterns within the region. Traffic volumes in the report are expressed in terms of annual average daily traffic (AADT), a standard measure of two-way daily volume that adjusts for weekly and seasonal variations in traffic. Toward the goal of keeping this information current, the data is updated annually.

The traffic volume data provides the region’s transportation planners, engineers, and administrators with basic information relevant to implementing traffic engineering improvements, modifying traffic control strategies, developing short-range highway improvement programs, establishing highway investment priorities, and monitoring traffic growth. The data has also provided the basis for calibrating CDTC’s regional traffic simulation model for regional corridor and sub-area planning studies. The availability of current data also serves the needs of the Capital District’s business community since many development decisions are partially influenced by the magnitude of traffic passing by a proposed development site. Finally, the data, in conjunction with highway condition data compiled by CDTC since 1983, aids the identification, selection, and prioritization of highway reconstruction projects for short-range planning evaluation and Transportation Improvement Program (TIP) development.

Selection of Roadways and Data Sources

The streets and highways for which traffic volumes are presented is limited to the region’s interstates, arterials, urban collectors, rural major collectors, and key rural minor collectors. These roadways were identified through the use of two data sources, both of which were created by NYSDOT. They are the Local Highway Inventory (for non-state roadways) and the Highway Sufficiency Ratings (for state touring routes and interstates). The sources of the traffic volume data are described below.

1. New York State Department of Transportation (NYSDOT) - Traffic volume data for highways on the state touring route system is obtained from the Department’s annual Traffic Data Report which includes the Department’s Traffic Volume Report. The NSYDOT report is based on yearly machine counts conducted by the Department at various locations. NYSDOT’s special and coverage count summaries – which include estimates of AADT for selected non-state streets and highways – are also reviewed and included. In addition, manual and mechanical counts performed by NYSDOT for specific planning, traffic, and design studies for non-state roadways are used to supplement the data collected from local sources.

2. New York State Thruway Authority (NYSTA) - Traffic volume data is provided by NYSTA for the New York State Thruway and its interchanges. Most of this data is included in the NYSDOT Traffic Data Report.

3. County Highway and Planning Departments - Traffic volume data for each of the county highway systems within the region has been compiled from summaries of traffic count activity undertaken by county governments since 1985. In the 1990’s, Albany County data was drawn primarily from manual and machine counts and were reported as AADT. Between 1995 and 2000, data reported by Saratoga County was based on machine counts conducted as part of its routine traffic count program. This data was reported in terms of average daily traffic (ADT) and was factored to AADT using CDTC's traffic count factoring procedures. Rensselaer County and Schenectady County provided traffic volume data when possible however the majority of their data was provided by a variety of local, state, and private sources. Since 2000, count data has been provided to CDTC on an ad hoc basis although several counties have since entered into the NYSDOT County Counter program.

4. Municipalities - City, town, and village planning and engineering departments provide traffic count information for local streets located on the region’s arterial and collector street system when available. In many cases, the data obtained from local agencies is factored to arrive at an AADT volume using CDTC's traffic count factoring procedures.

5. Engineering, Planning, and Traffic Impact Studies - Planning and traffic engineering studies also provide current traffic data for non-state roadways. Examples include CDTC’s Community and Transportation Linkage Planning Program studies, traffic impact studies prepared by private consultants; and NYSDOT Expanded Project Proposals, Planning/Engineering Studies, and design studies when available.

6. Capital District Transportation Committee - Manual counts obtained by the CDTC staff are also used. This data is collected for the afternoon peak hour on various Capital District roadways. The manual counts are factored to AADT using CDTC’s traffic count factoring procedures. CDTC also hired a consultant to conduct manual counts at various locations throughout the Capital District in 1997. This data was provided for the peak hour and factored to AADT using the factoring procedures.

7. Estimates – Despite the existence of the traffic volume report since 1980’s, there are a number of roadways for which no traffic count information is available. Traffic volumes for these highway segments were estimated based on information provided in CDTC's STEP Model. Many other street and highway segments have not been counted since the late 1980's and early 1990's. As a result, growth factors derived from CDTC's STEP Model were applied to all traffic counts or traffic volume estimates made prior to 1995. The growth factors allowed for an estimation of 1999 traffic volumes.

Traffic Count Factors

As discussed, CDTC uses two methods for factoring traffic volume data depending on the original data source. For instances where an ADT must be expanded to estimate an AADT, the following factors are applied.

Average Daily Traffic (ADT) to Average Annual Daily Traffic (AADT) Factors

Count Month	Factor*	Count Month	Factor*
January (1)	1.191	July (7)	0.895
February (2)	1.167	August (8)	0.864
March (3)	1.078	September (9)	0.866
April (4)	0.972	October (10)	0.912
May (5)	0.930	November (11)	1.005
June (6)	0.900	December (12)	1.092
*Combined monthly and heavy vehicle factors.
SOURCE: CDTC

For instances where a peak hour count must be expanded to estimate an AADT, the following ratios are applied.

Estimated Peak Hour-to-AADT Ratios for Capital District

Streets and Highways by Functional Classification

Functional Classification		Peak Hour/AADT (percent)
Interstate System:	Urban	10.3
	Rural	9.3
Arterial System:	Principal Urban Expressway	12.1
	Principal Urban Non-Expressway	9.7
	Principal Rural	9.6
	Minor Urban	9.7
	Minor Rural	9.8
Collector System:	Urban	10.1
	Rural Major	10.7
SOURCE: CDTC

Data Presentation

The traffic volume data is available on CDTC’s website in a downloadable table format (.pdf) or as a web page (html). CDTC also has a hardcopy version of the data table available upon request. The information presented in the data table includes the following:

1. Facility - This column identifies the roadway name and/or number on which the count was taken. The route name/number is the official U.S., New York, or county highway route number, or local street name. The name/number is posted along the highway or local road and appears on road maps available to the public.

2. Common Name (if different than facility) - If the facility identified in the first column is known by another name, it is identified in this column. For example, I-87 in Albany County and Saratoga County is more commonly referred to as the Northway.

3. Segment - The location at which each traffic count segment begins and ends is described in this column. The segment represents a stretch of highway on which the traffic is expected to remain fairly constant. A segment generally begins and ends at intersections with other major highways, wherever a major traffic generator is located, or at municipal boundaries.

4. County - This column identifies the county in which each street or highway is located. In instances where a road segment crosses a boundary, two counties are identified.

5. Functional Classification - The functional classification of each street and highway is identified. The functional classification assigned to a street or highway represents the class or category of a given facility that best represents the character of service the facility provides in the road network hierarchy.

6. Volume - This value represents the estimated annual average daily traffic (AADT) volume for the year in which the data was compiled. Data sources are described above.

7. Year of Count - This is the year in which the most recent traffic count was conducted or an estimate was made for a particular highway section.

8. Count Source (Description) - The information set forth in this column identifies the source of the traffic volume data summarized in the report. Each road segment is provided a code to represent the source of the initial traffic volume data and a description of that data including any adjustments made from the original count.

To request a copy of the current traffic volume data tables, please contact Sandy Misiewicz at (518) 458-2161 or email cdtc@cdtcmpo.org.

Last Updated September 2011.