KYOVA Metropolitan Planning Organization

INPUT DATA AND ASSUMPTION

This Section describes the input data required for each step of the sequential travel demands models for 2000. This data will used to produce the 2000 travel estimates to validate accuracy of the models. These data include the socioeconomic, special trip generators, the modeling net work, and traffic counts

Socioeconomic Data Development

Statistical studies have shown a significant correlation between the demographic/economic characteristics of an area and the trip making characteristics of the area. The travel forecast model for the Huntington Metropolitan Transportation Plan uses the socioeconomic information of dwelling units, population, employment by type (basic retail and non retail), labor force, automobile ownership and school enrollment by (school K-12, attendance college and residents students) to estimate the number of trips generated within the region.

The socioeconomic data were developed by the KYOVA Interstate Planning Commission. For the purpose of transportation modeling for the Huntington area was divided into 397 internal traffic analysis zones (TAZs) ( Eighty-eight zones in Ohio; 179 zones are in West Virginia; and 130 zones are Kentucky), 3000 nodes and 6000 links. 398 thru 425 are the external cordon line stations. TAZs are small geographic areas with boundaries comprised of roadways, waterways or other defining physical features. The land use within each zone is generally homogeneous and may be all residential, all commercial, or all industrial (or mix). The socioeconomic data were disaggregated to correspond to TAZ level. The data for these TAZs were thoroughly reviewed and updated for the updated for the 2000 base year. Development of the socioeconomic data is documented in Chapter 6 Of the HIATS 2020 Long Range Transportation Plan (LRTP). Projections of the socioeconomic data for the future year 2030 were conducted by KYOVA. Projecting the future year socioeconomic data allows for the estimation of future year vehicle travel demand. .

SPECIAL TRIP GENERATORS

Special trip generation input data are used to estimate the trip making characteristics of specialized land uses (special generators) internal to the transportation study area. Special generators are major land uses for which the standard trip generation and distribution equations are not expected to produce reliable estimates of their travel patterns. They augment or override information from the trip generation portion of the travel demand modeling process.

The list of special generators includes major facilities and shopping areas such as Tri-state Airport and Huntington Mall, the peripheral communities, and institutions such as Marshall University. To assure greater accuracy in Trip attractions to major generators, special trip attraction rates were developed in prior modeling efforts. 2000 data for each special generator was obtained by contacting the appropriate official at these special generates; National Cooperative Highway Research Program (NCHRP) Report, Trip Generation, 7^th Edition by Institute of Transportation Engineers (ITE) Reference. Data collected varied from square foot of commercial area, enrollment, population, to annual passengers depending on the nature of the special generator. If a special generator is classified as a uniform land use generator (UNILUSG) (special generator occupies whole TAZ), then only trips calculated as a result of the trip rate would be used. If on the other hand, a special generator is classified as a mixed land use generator (MIXLUSG) (special generator occupies par of TAZ), then trips calculated as a result of trip rate would be added to trips produced by applying the appropriate regression equation for the remainder of the zone

EXTERNAL STATIONS AND TRIPS

External stations are points on the boundary (or cordon line) of the transportation study area where significant amounts of travelers ( usually highway traffic ) enter and exit the area. In KYOVA's 28 external stations are established. Figure shows the geographical locations of the 2000 cordonline stations and their corresponding external station numbers as established in the Traffic Counting Program. Travel at an external station represent both through travel ( sometimes called "E-E" Trips), and other external trips ( sometimes called "I-E" Trips). Both "E-E" and "E-I" trips are auto or truck trips with at least one end of the trip outside of the transportation study area. These trips are estimated from traffic counts taken at the cordonline . A 2000 traffic count set at the 28 external stations was used to determine the external trips in the study area .. The basis for the percent split between car and truck within each trip purpose is based on the 1971 Origin-Destination (O-D) survey.

Centroid Connectors

Centroids are the "center of activity " of a zone. They do not represent the geographic center of the TAZ, unless development is uniform within the zone. The role of a centroid connector is to load the trips produced by a zone into the street network. As a result, they represent the local street system which plays this function. The coded speed on a centroid connector varies from 15 to 25 mph depending upon the area type (urban, rural, CBD) in which the centroid connector belongs.

BUILD HIGHWAY NETWORK

In order to use the QRSII software package, the existing roadway system must be represented by a QRSII highway network. The process of translating the highway system into a computer based representation is known as network coding. The basic elements of a network are nodes and links. Links represent actual roadways found in the highway system. Nodes are the end-points of links connecting links together. Since links are representations of existing roadways, they are coded with the characteristics of those roadways. Coded characteristics include speeds, distances, capacities, number of lanes, functional classification type, area type and count data.

After the QRSII network coded, it was compared to the real highway system for accuracy. This was done by reviewing the "highway paths" or the minimum time routes between traffic analysis zones(TAZs) of the study area. An extensive review of the highway paths was done to ensure that the network accurately represented the routes people take in their daily travel within the region.

NETWORK REPRESENTATION AND ROADWAYS

All regionally significant roadways classified as collector or better have been included in the travel demand models. The major roadway attributes used in the model are noted in Table 2. Additional link and node data items are presented in Table 3.

Nodes-Point Data:

The nodes represent: 1) intersections that facilitate traffic flow between links or between traffic analysis zone centroids and the network, 2) external stations and 3) �dummy� nodes to more accurately reflect curvature along the road. In the model there are:

� external stations - 27

� zone centriods- 483

� nodes � 7300

� signalized intersections � 223 (20 in Wayne County, 35 in Lawrence County, 147 in Cabell County and 38 in Boyd/Greenup Counties).

Zone centroids represent the trip ends associated with the origin and destination of trips entering the roadway networks. External stations represent the origin and/or destination of trips having at least one end located externally to the study area. The data included for each node representation are as follows:

A- Traffic Analysis Zones

HIATS existing transportation study consists of 397 small geographical areas known as Traffic Analysis Zones (TAZ). The boundary of these TAZs was established with the following characteristics ans objectives:

1- Zones should contain relatively homogenous land uses;

2- Zones should be structured such that they all generate the same number of trips;

3- Natural barriers such as rivers and steams should be used as zone boundaries;

4- Man- made barriers such as freeways and railroads should be used as zone boundaries;

5- Zones should be relatively compact in shape.

All efforts were made to satisfy as many of the above objectives as possible. However, in some places these objectives were found to be incompatible.

Practical considerations dictate that TAZs nest within census tract boundaries. Census tracts may be aggregated or disaggregated as necessary, but the census tract boundaries must be preserved to facilitate working with the census.

B- Calibration and validation data

Calibration data is used to determine the parameters and constants of the models travel demand equations. Validation data is used to determine the accuracy of the model traffic patronage estimates, i.e how well does the model perform on a known data set? Calibration data is vital to ensure the accuracy of individual equations and parameters used in the model. Validation data is vital to test the overall validity of the model's estimates (forecasts).

The best source of model estimation and calibration data is a local household travel survey that is relatively recent (no more than 10 years old). The 2000Census Transportation Planning Package (CTPP) is the next best source of travel behavior data (however, it gives information only on commuter travel).

The CTPP is an extensive collection of summary tables developed from 1990 census data. Tables are provided for a number of geographic levels, from population and households characteristics by place of residence, worker characteristics by place of work, and detailed commuter (journey-to-work) information.

C- Traffic Counts

The validation of travel demand model requires comparing model generated traffic data against observed traffic data. HIAT's 1990 traffic counts data will serve as abase for the observed traffic data. These counts are transferred into the 1990 link file network to allow comparing the assigned volume against the ground counts.

D- Vehicle Occupancy

The next step in the four step travel demand process was to factor the trip table generated in the trip distribution step into automobile and transit trips. Because the Huntington region has very low transit ridership, as a percent of all trips, all person trips were assumed to be made by automobile or commercial vehicles. The auto occupancy factions utilized were utilized as follows:

HBW = 1.08 persons/vehicle

HBO = 1.20 persons/vehicle

HBW School = 3.58 person/vehicle

NHB = 1.15 person/vehicle

CMV = 1.00 person/vehicle