Phone: 304-523-7434
Fax: 304-529-7229

400 Third Avenue
P.O. Box 939
Huntington, West Virginia 25712
Chairman
Robert E. Pasley

Executive Director
Chris Chiles

FINAL DRAFT REPORT

UPDATING AND VALIDATING THE TRAVEL DEMAND FORECASTING PROCESS

 Transportation Modeling Using Quick Response System II
or Huntington- Ironton Area Transportation Study

KYOVA Interstate Planning Commission
400 Third Avenue
Huntington, WV 25701

October 04

The purpose of this report is to present the details of the methodology followed in implementing the travel demand forecasting process using the Quick Response System II (QRSII) Version 7.0 with advanced General Network Editor (GNE)Version 7.0 Transportation Planning Computer Software package. Known travel data for the year 2000 was used to verify the outputs of existing transportation models. Most of FHWA urban model calibration targets have been met by this model. The trip generated model produced expected trip end volumes. The trip distribution model resulted in average trip length comparable to other travel studies and the traffic assignments produced volumes reasonably within FHWA standards. Therefore, the model can be used in forecasting 2030 traffic to examine the future capacity deficiencies and to perform future year plan development and analysis.

In the past, KYOVA Interstate Planning Commission and the West Virginia Division of Highways have used both household origin-destination surveys and mathematical techniques in formulation of traffic models. The approach which has proven the most practical for small and medium urban areas as well as larger areas, such as the Huntington-Ironton Areas Transportation Study (HIATS) urbanized area, has been the mathematical simulation of internal and external travel. This technique involves the development of trip generation equations based on the relationships found valid in past studies and parameters calibrated for the particular area under study. This approach was adopted for the Huntington-Ironton area to simulate traffic for both present (2000) and the future (2030).

 

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INTRODUCTION

            This report describes development of an updated Quick Response System II (QRS11) Transportation Demand Model for the Huntington, West Virginia Metropolitan Area.  The previous model developed in the mid-1990’s was utilized in developing the 2025 Long-Range Transportation Study for the Huntington Ashland-Ironton (HAITS) region by the KYOVA Interstate Planning Commission [1].  The previous travel demand model utilized QRSII software and represented the areas KYOVA was responsible for in 1990 (Cabell and Wayne Counties in West Virginia and Lawrence County in Ohio) and excluded the Kentucky Counties.  The current model includes Cabell and Wayne Counties in West Virginia, Lawrence County in Ohio and Boyd and Greenup Counties in Kentucky.

            The decision was made to utilize the framework of the HAITS model and supplement it with the recently completed Ashland Travel Model conduct by the Corradino Group [2].  The Ashland model was developed in TransCAD which is not directly compatible with the QRSII software.  The parameters of the HAITS model were developed by earlier studies used to produce the 1990 and 2000 Long-Range Plan [3][4].

            The major activities involved:

1.                  Expand the traffic analysis zone (TAZ) structure to include all of Cabell, Wayne and Lawrence Counties.  The TAZ’s structure developed for the two Kentucky Counties, Boyd and Greenup Counties, as part of the Ashland Travel Model were adopted for inclusion in this study.  The TAZ’s by county are as follows:

	Wilbur Smith - HAIATS Model [4}	HAITS Model [1]	2004 Updated Model
Base Year Data	1970	1990	2000
Lawrence Co., Ohio	88	88	98
Cabell Co., WV	138	138	158
Wayne Co., WV	41	41	47
Greenup Co. KY	130	--	60
Boyd Co., KY		--	120
Internal Zones – Total	397	267	483
External Stations - Total	28	28	27

In Ohio and West Virginia the expanded TAZ structure added an additional 57,379 persons over a base population of 143, 772 from the 1990 study (Table 1).  The revised TAZ structure for the Ohio and West Virginia Counties was presented as the “1999 TAZ District Map” in the KYOVA Year 2025 Long Range Transportation Plan [1].  The 1990 socio-economic profile for each TAZ was updated from the 2000 census.  The updated variables for each TAZ included:

a.      Dwelling Units

b.      Population

c.      Labor Force

d.      Non-Retail Employment

e.      Retail Employment

f.        Automobile Ownership

g.      School Attendance

h.      Resident Students

The network was extensively edited to remove extraneous nodes and links in order to better reflect the regional highway system.  Additional roadways constructed since the original networks were added as links.       

Table 1

Population By Counties Included in 2004 Travel Model

	TAZ Number	1990 Population	2000 Population
Lawrence Co., OH	1-88	52,732	48,585
	600-609	---	12,892
	Sub Total	52,732	61,477
Wayne Co. WV	186-226	19,042	19,446
	550-555	---	23,438
	Sub Total	19,042	42,884
Cabell Co. WV	89-185 227-267	85,123	75,741
	550-519	--	21,049
	Sub Total	85,123	96,790
WV and OH Study Area		156,897	201,151
Greenup Co. KY		---	36,891
Boyd Co., KY		---	49,752
Total Study Area		156,897	287,794

Source: [1], Chpt. 6

 

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:

 

Table 2  Roadway Characteristics in Network 

Roadway Type	Functional Class FC	Saturation Flow in PCEs/Hour/Lane	Posted Speed** (mph)
Rural
·        Freeway	1	1700-2400	65-70
·        Principal, Minor Arterials and Major Collections	2-7	1200-1700	45-55
·        Minor Collections and Locals	8-9	1000-1700	35-45
Urban
·        Freeway	11-12	1600-2400	55-65
·        Principal Interials	14	1000-1490	40-45
·        Minor Arterials	16	910-1385	35-40
·        Collection	17	910-1385	30-40
·        Local	19	910-1385	25-35

*Varies by Specific Location

**Depends on State Regulations

Table 3  Node – Link Input Variables 

Node Input Variables

Link Input Variables

Intersection w/o Delay 1.      Area Weight 2.      Production Extra Time 3.      Attraction Extra Time Intersection w/Delay 1.      Through Adjustment 2.      Left Adjustment 3.      Immediate Right Adjustment 4.      Other Movements Adjustment 5.      Cycle Length 6.      Minimum Unsignalized Capacity 7.      U-Turns Allowed 8.      Areas Weight 9.      Production Extra Time 10. Attraction Extra Time 11. Unit Extension   Centroid 1.      School Enrollment 2.      Number of Automobiles 3.      Number of Retail Employees 4.      Number of Non-Retail Employees 5.      Number of Dwelling Units 6.      Intrazonal Travel Time 7.      Total Labor Force 8.      Total School Attendance 9.      Intrazonal Trips 10. Type and Parameter Set   External Station 1.      HBW Productions 2.      HBNW Productions 3.      HB? Productions 4.      NHB Productions 5.      HBW Attractions 6.      HBNW Attractions 7.      HB? Attractions 8.      NHB Attractions 9.      Travel Time from Seed

Two-way Street (one ways same w/o B-A) 1.      Approach Codes – Through Traffic Codes, Lane geometry, Progression Code, Functional Class, Cross-Section 2.      Free Speed 3.      Travel Time A-B 4.      Travel Time B-A 5.      Base Volume A-B 6.      Base Volume B-A 7.      Hourly Sat. Flow A-B 8.      Hourly Sat. Flow B-A 9.      Free Travel Time 10. Distance 11. Federal Functional Class 12. AADT Count 200 13. Posted Speed Limit 14. Lanes Each Direction 15.  Volume A-B 16. Volume B-A Centroid Connector 1.      Speed 2.      Travel Time A-B 3.      Travel Time B-A 4.      Distance 5.      Volume A-B 6.      Volume B-A

 

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1.                  Zone centroids: Year 2000 socio-economic characteristics used to estimate trip ends for the following trips:

·        Home based work trips

·        Home based other trips

·        Non-home based trips

·        School trips

·        Commercial – truck trips

·        Internal-External trips

2.         External Stations:  The locations where major roadways cross the study cordon line were defined as external stations.  A list of external stations is recorded in Table 4.    Each station was associated with an estimate of:

·        Total Average Annual Daily Traffic (AADT) for Year 2000

·        Internal-External AADT for Year 2000

·        External-External Traffic AADT for Year 2000

·        Trip Purpose Allocation for Home Based Work, Home Based School, Home Based Other, Non-Home Based Trips

Link Data:

                 Links represent sections of roadway traveled by vehicles.  Most links were part of the regional highway network and were characterized by:  functional classification, speed, capacity, etc.  Ultimately the number of vehicles assigned to a link represents the vehicle utilization of the regional highway networks.  Other links represent zonal centroid connectors or the local road system, which connected the zone centroids to the regional highway systems.  There are 1,056 zone centroid connector links and over 7,000 roadway links.

Table 4  External Stations 

	Station Number	State	AADT Volume 2000
9001	US52 W	OH	9731
9002	OH522	OH	677
9003	OH93	OH	1798
9004	OH141	OH	843
9005	OH7 E	OH	2542
9006	WV2 E	WV	3733
9007	Mason Rd	WV	1467
9008	I-64 E	WV	32667
9009	US60 W	WV	14333
9010	Bulls Gap	WV	467
9011	WV10	WV	3667
9012	CR21	WV	300
9013	WV37 E	WV	717
9014	12-Pole Creek Rd	WV	317
9015	US52 S	WV	6300
9016	WV73 W	WV	9900
9017	US23 S	KY	9560
9018	KY3	KY	816
9019	US60 W	KY	3873
9020	I-64 W	KY	18791
9021	KY207 W	KY	305
9022	KY1 S	KY	2340
9023	KY2 W	KY	1098
9024	KYAA W	KY	1405
9025	KY8 W	KY	6590
9026	US23 N	KY	12200
9027	KYAAE	KY	8300

 

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TRIP GENERATION

Regression Equations:

            A decision was made to utilize the trip generation relationships applied in the current KYOVA travel demand model to simulate person traffic for 2000 (validation) and 2005-2030 (forecasting) [1].  The KYOVA model relationships were based on the original HAIATS model developed in the late 1960s by Wilbur Smith and Associates [3].  These equations were utilized in the “1973 Major Review and 2000 Plan Update” and “Year 2025 Long-Range Transportation Plan”[4][5].

The HAIATS and KYOVA trip generation module included six trip purposes.  They are:

·        Home Based Work (HBW)

·        Home Based Other (HBO)

·        Non-Home Based (NHB)

·        Commercial Motor Vehicle* (CMV)

·        Internal-External/External-Internal

·        Home Based School (HBS)

Traditionally trip production models were used to estimate the number of trips generated at the TAZ.  It is generally accepted that the characteristics of the household best determine trip end productions.  Similarly the attraction equations determine the number of trip ends attracted typically to non-residential land uses.  The equations utilized to estimate trip ends for each TAZ were as follows:

·        Productions

HBW = -8.25 + 1.74 TAZ Labor Force

HBO =   3.42 + 3.61 TAZ Auto Ownership

HBS =    3.36 + 1.82 TAZ School Enrollment

 

·        Attractions

HBO = 7.58 + 1.77 TAZ Total Employment

HBO = 65.10 + 10.58 TAZ Retail

                  Employment + 1.48 TAZ

                  Dwelling Unit + .44

                  TAZ Other Employment

HBS = 7.08 + 1.50 TAZ Total School Attendance

·        Production/Attractions

NHB = -14.68 + 4.70 TAZ Retail

                  Employment + .81 TAZ Other

                  Employment + .81 TAZ Dwelling

                  Units + .20 TAZ Total School Attendance

Truck = 12.32 + .52 TAZ Retail

                  Employment + .23 TAZ

                  Other Employment + .28

                  TAZ Dwelling Units

Internal-External = 31.93 + 1.19 TAZ Retail Employment

                              + .26 TAZ Other Employment + .10 TAZ

                              Dwelling Units + .05 TAZ Total School Attractions

 

            The independent variables used in the equations are defined as follows:

                        Dwelling Units – Dwelling Units

Automobile Ownership - Automobiles Garaged in the Zone of   Resident

                        Labor Force – Total Resident Labor Force

School Enrollment –   Total Resident Students including Primary,  Secondary Attendant, and College Students

                        Retail Employment – Retail Employment within the Analysis Zone

Other Employment – Non-retail Employment within the Analysis  Zone

            These trips were defined as daily person trips using all modes of travel. The model update did not include any significant changes to the original HAITS travel demand model.  The Kentucky zones whose data were developed from the Ashland Travel Study were analyzed with the HAITS trip generation travel relationships.

Base Year Socio-Economic Factors:

            In order to estimate trip productions and attractions by TAZ, socio-economic data were obtained from the 2000 census.  For the Kentucky zones the Ashland study relied on different independent variables to estimate trip productions and attractions, since the Census information was not available by zone and had to be estimated.  This process was completed by the KYOVA staff and Sam Granato of the Ohio Department of Transportation.  The characteristics of the study area are noted in Table 5 and compares the 1990 KYOVA study to the current 2000 study for those portions of the study area that are directly comparable.  In this area the population decreased 8.3 percent between 1990 and 2000.  Likewise the labor force declined 20.3 percent and auto ownership declined 8.6 percent, while employment for the comparable Huntington/Ironton area increased 13.6 percent.  The new areas of Lawrence, Wayne and Cabell counties and the two Kentucky counties almost doubled the population of the study area.  In the expanded area auto ownership was at a slightly lower rate than in the original study area (population/auto of 1.60 vs 1.67), labor force was at a slightly higher rate (labor force/population .37 vs. .40), but employment was at a lower rate than exists in the original study area (employment/population .59 vs. .38).  These demographic shifts will have implications on the number of trip ends estimated by trip purpose.  The major shifts are reported in Table 6. 

Table 5 Socio-Econ Trends – 1990 and 2000 Study Comparisons 

Comparable Area	1990		2000	Percent Change
Population	156,897		143,772	-8.3%
Labor Force	67,702		53,969	-20.3%
Employment	75,275		85,513	+13.6
Auto Ownership	94,066		85,982	-8.6
Population/Auto	1.67		1.67	---
If/Population	.43		.37	-14.0
Employment/Population	.48		.59	+22.9
New Area 2000
Population		144,018
Labor Force		57,384
Employment		54,554
Auto		89,843
Population/Auto		1.60
If/Population		.40
Employment/Population		.38
Current Study Area 2000
Population		287,790
Labor Force		111,353
Employment		140,060
Auto		175,837
Population/Auto		1.64
If/Population		.39
Employment/Population		.49

 1990 Data reported in HAITS – Long Range Plan 2025 [1].
 

Table 6 Demographic Shifts 1990 vs 2000 Study

 

	1990				2000
	Pop. du.	Pop. auto.	If pop.	Emp. Pop.	Pop. du.	Pop. auto.	If Pop.	Emp. Pop.
Comparable Area	2.41	1.67	.43	.48	2.35	1.67	.37	.59
New Area					2.54	1.60	.40	.38
Total Study Area	2.41	1.67	.43	.48	2.44	1.64	.39	.49

 

1990 Data reported in HAITS Long Range Plan 2025 [1].

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Estimates of Trip Productions by TAZ 

            After applying the regression equations, estimates were made of trip productions and trip attractions by TAZ.  A summary by County and State is presented in Table 7. 

Greater reliance was placed on the estimate of trip productions, which provides good regional control totals.  The person trips per household or per capita can be compared to external sources to determine if trip making in the Huntington Metropolitan Area reflects typical conditions.  The comparisons are provided in Table 8 and indicate that the Huntington trip rates at 10.7 household person trips per day and 4.4 per capita person trips per day was compatible with national sources although on the high side.  National sources suggest the appropriate household trip rates for a community of 300,000 was on the order of 11.8-7.6 trips per day from NCHRP Report 187 [6], 9.0 trips per day from NCHRP Report 365 [7] or 10.7 trips per day for the 1995 National Personal Transportation Study [8] (Table 8).  However, it is generally accepted that trip making in smaller communities has higher household trip rates than larger urban areas.  The Huntington distribution of trips by trip purpose indicated about 15 percent HBW, 50 percent HBO, 26 percent NHB and 9 percent HBS.  These percentages were compatible with household trip rate data recently collected in Tennessee (see Table 9) [9].  National guidelines have been published for trip generation and are presented in Table 10 [10].  The trip generation relationships indicate the rates calculated for the Huntington Metropolitan Area were generally within the guidelines.       

Table 7 2000 Study Area 

Population	287,794*
Auto Ownership	175,837
Household	117,690*
Population/Household =	2.45
Population/Auto =	1.64
Person Trips/Household	10.7**
Person Trips/Capita	4.4
Percent Trips
HBW	15.1
HBO	50.3
NHB	25.7
HBS	8.9
Total	100.0

 

  *2000 Census Data

**Ashland used 10.4 trips per household with 20% HBW, 55% HBO

    and 25% NHB. [2]

    Households are defined for TAZ Socio-Economic data and are used as DU’s.

 

Table 8 Comparative National Trip Rate Data 

NCHRP 187			NCHRP 365		NPTS
Urbanized Area Population	Person  Trips/ Household		Urbanized Area Population	Person  Trips/ Household	Urbanized Area Population	Person Trips/ Household
50,000 to 100,000	14.1		50,000 to 200,000	9.2	Less Than 250,000	10.8
100,000 to 250,000	11.8		200,000 to 500,000	9.0	250,000 to 499,999	10.7
250,000 to 750,000	7.6		500,000 to 1,000,000	8.6	500,000 to 999,999	10.7
750,000 to 2,000,000	7.6		>1,000,000	8.5	1,000,000 to 2,999,999	10.4
					Overall	10.5
Conditions:  early 1970’s		Conditions:  early 1980’s			Conditions: mid-1990’s

 

Source 1        NCHRP 187 [6]

Source 2        NCHRP 365 [7]

Source 3        NPTS – National Personal Transportation Survey [8]

 

Table 9 Person Trip Summary by Household (Total and By Purpose) 

MPO	n	Total Trips/hh	HBW		HBS
			Trip/hh	%	Trip/hh	%
Chattanooga	816	7.53	1.49	19.79	0.12	1.59
Knoxville	1381	8.04	1.21	15.08	0.50	8.52
Nashville	1817	8.44	1.38	16.60	0.50	6.02
Memphis	2229	8.27	1.57	19.01	1.04	12.58

 

MPO	HBO		NHB		HBW&S
	Trip/hh	%	Trip/hh	%	Trip/hh	%
Chattanooga	3.19	42.36	2.73	36.25	1.61	21.38
Knoxville	3.44	42.72	2.71	33.68	1.90	23.60
Nashville	3.65	44.02	2.76	33.35	1.87	22.63
Memphis	3.46	41.87	2.19	26.54	2.61	31.59

 

 

HBW = Home Base Work Trip

HBS = Home Base School Trip

HBO = Home Base Other Trip

NHB = Non-Home Base Trip

HBW & HBS = Combination of Home Base Work and School Trips

Total Trip Rate = Combination of HBW, HBS, HBO, and NHB

 

Source [9] 

Table 10 Trip Generation Calibration Guideline 

National Experience	2000 Huntington Study
Person Trips per Household: 8.5 to 10.5	10.7
HBW Person Trips per Household: 1.7 to 2.3*	2.6
HBO Person Trips per Household: 3.5 to 4.8	5.4
NHB Person Trips per Household: 1.7 to 2.9	2.8
NBW Trips: 18%  to 27% of all Trips*	24%
HBO Trips: 47% to 54% of all Trips	50%
NHB Trips: 22% to 31% of all Trips	26%

*Includes home based school trips

  Source [10]

Comparisons are provided in Table 11 with the early KYOVA traffic model calibrated with 1990 data.  Since labor force and school enrollment declined between 1990 and 2000, the percent of home based work and school trips also declined.  Increases in employment increased the percent of non-home based, and home based other trips.  For both models internal trips remained between 91 to 92 percent of all vehicle trips between 1990 and 2000, but the percent of the work and school trips declined. After applying vehicle or occupancy factors there were 7.5 auto trips per household, 3.5 auto trips per person and 8.1 vehicle trips per household.  Table 12 presents the county household trip rates and trip purpose distribution by county.

 

Internal-External Trips (IE/EI)

            Internal-external and external-internal trips were movement that cross the study boundary (cordon-line).  One portion of the movement had a trip end within the study area and the other trip end was outside the study area.  The estimates of EI/IE were provided by Sam Granato of the Ohio Department of Transportation based upon an analysis of average annual daily traffic (AADT) at the external station.  Using default values derived from other sources and local knowledge these trips were distributed by trip purposes as noted in Table 13.  The analysis was based on recent data collected for the region including bridge origin-destination interviews conducted by the Ohio Department of Transportation.  It was assumed only 7 percent of the trips were classified as external-external to the study area.  With a year 2000 AADT of 160,000 vehicles at external stations,

Table 11 Trip Comparisons 1990 vs 2000 Studies 

Person Trips
	1990*		2000
HBW	155,000	18%	190,038	15%
HBS	146,000	17%	113,364	9%
HBO	355,000	41%	636,420	50%
NHB	204,000	24%	325,327	26%
Total	860,000		1,265,147

 

Vehicle Trips
	1990		2000
HBW	122,000	21%	175,961	18.3%
HBS	32,000	6%	31,666	3.3%
HBO	216,000	38%	388,061	40.5%
NHB	151,000	26%	282,893	29.5%
Sub-total	521,000	91%	878,581	91.6%
Truck	50,000	9%	79,592	8.4%
Total	571,000	100%	958,173	100%

 

1990		2004	2000
	*Occupancy Used in 1990	* Occupancy Used in Study	Ashland, KY Occupancy
HBW	1.27	1.08	1.11
HBS	4.56	3.58
HBO	1.64	1.20	1.58
NHB	1.35	1.15	1.66

1990 Data in HIATS Long Range Plan – Technical Analysis 1997

*Data from Clarksville Tennessee study [11]

Table 12 2000 TAZ Data Summary Table 

	HBW	HBNWP	School P	NHBP	% Trips P
					HBW	HBNW	School	NHHB	Trips/pop	Trips/DU
Wayne	25,971	91,090	14,555	31,157	16%	56%	9%	19%	3.8	9.4
Cabell	64,142	203,851	40,286	142,628	14%	45%	9%	32%	4.7	10.9
Lawrence	37,095	142,202	23,924	48,935	15%	56%	9%	19%	4.0	10.2
Greenup	26,576	87,843	14,214	29,507	17%	56%	9%	19%	4.3	10.9
Boyd	36,252	111,432	20,382	73,097	15%	46%	8%	30%	4.8	12.1
Total	190,037	636,420	113,364	325,326	15%	50%	9%	26%	4.4	10.7

  

Table 13  External Station 

	Station Number	AADT Volume 2000	Thru Trips	XHBW-P	XHOB-P	XHOB-P	XNHB-P
9001	US52 W	9731	364	1232	33	1236	2183
9002	OH522	677	0	89	2	89	158
9003	OH93	1798	0	236	6	237	419
9004	OH141	843	0	111	3	111	196
9005	OH7 E	2542	140	316	8	317	560
9006	WV2 E	3733	19	488	13	490	865
9007	Mason Rd	1467	0	193	5	194	342
9008	I-64 E	32667	1188	4139	110	4155	7335
9009	US60 W	14333	0	1885	50	1892	3340
9010	Bulls Gap	467	0	61	2	62	109
9011	WV10	3667	16	480	13	482	851
9012	CR21	300	0	39	1	40	70
9013	WV37 E	717	0	94	3	95	167
9014	12-Pole Creek Rd	317	0	42	1	42	74
9015	US52 S	6300	0	828	22	832	1468
9016	WV73 W	9900	0	1302	35	1307	2307
9017	US23 S	9560	723	1162	31	1166	2059
9018	KY3	816	0	107	3	108	190
9019	US60 W	3873	0	509	14	511	902
9020	I-64 W	18791	1613	2259	60	2267	4002
9021	KY207 W	305	0	40	1	40	71
9022	KY1 S	2340	0	308	8	309	545
9023	KY2 W	1098	0	144	4	145	256
9024	KYAA W	1405	69	176	5	176	311
9025	KY8 W	6590	3560	398	11	400	706
9026	US23 N	12200	3641	1126	30	1130	1994
9027	KYAAE	8300	34	1087	29	1091	1926

26% were assigned as home based work, 1% home based school, 26% home based other and 47% non-home based vehicle trips ends (Table 13).  The internal-external trip generation regression equation discussed earlier was utilized in calculating the internal location of the trip end.

External-External Trips

            An estimated 11,400 trips were determined by Sam Granato of the Ohio Department of Transportation as crossing through the Huntington Metropolitan Area.  The resulting external-external matrix is presented in Table 13.  The external-external trips were defined in an external trip table and were defined as vehicle trips.

Total Area-wide Trips

            In Table 14, a summary of vehicle trips by trip category were defined and compared to the 1990 HAITS calibrated model.  The 1990 network reported a higher percent of external-external trips, but since the study excluded the two Kentucky Counties some internal trips between Kentucky and Ohio or West Virginia would have been defined as external travel.  Outside of this situation there was a similar allocation of trips between the two studies.

BALANCING PRODUCTIONS AND ATTRACTIONS

            Since different mathematical models were utilized in estimating trip productions and attractions it was necessary to reconcile any differences.   Over a 24 hour period it was assumed each production has an attraction.  Thus, its

Table 14 Vehicle Trip Type 

	1990*		2000
	Vehicle trips	%	Vehicle trips	%
Internal	562,000
Truck
Sub Total	562,000	85%	958,173	86%
Ext./Int.	75,000	11%	147,991	13%
Ext./Ext.	25,000	4%	11,367	1%
TOTAL	662,000		1,117,531

**KYOVA Table 4.7 Does Not Include KY [1]

1990 Data from HIATS Long Range 2025 Plan [1]necessary for productions and attractions to balance before applying the gravity model in trip distribution.  For this analysis, HBW and HBO trip attractions were balanced to the trip production totals.  Since the same regression equation was used to estimate NHB and truck trip productions, balancing was not required.

 

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TRIP DISTRIBUTION

Internal Trips Gravity Model

Once the trip ends, in terms of productions and attractions, were estimate by TAZ, then the trip distribution models determined the trip linkage between zones.  For internal travel the gravity model has been traditionally utilized.  Its mathematical form is:

            Where:

            T_ij        =          Trip from zone i to zone j

            P_i         =          Total trips sent from zone i (trip generation)

            A_j         =          Total trips received by zone j (trip attraction)

            F_ij        =          Travel time factor between zone i and zone j

            A key component in applying the gravity model was the friction factors or trip length distribution for trips of different purposes.  Without a recent origin-destination or household travel survey, the friction factors had to be estimated from secondary sources.  In this application the friction factors were utilized from the previous QRSII model.  The factors depended on the shortest travel time calculated between zones.

            The gravity model was calibrated to represent trip distributions within the Huntington Model area.  An iterative process was applied where average trip lengths were compared to estimated trip lengths.  Without a recent locally derived trip length frequency curve a relationship assumed to reflect local conditions was taken from previous models [5].  Thirty iterations were made with exponential factors.  The exponential values used are as follows:

            HBW = .15

            HBO = .18

            HB School = .27

            NHB = .18

            CMV = .18

 

            Terminal trips were not utilized.

            A trip distribution trip table was produced, which included trips between TAZ’s (internal-internal I-I) and between TAZs and external stations (internal-external I-E).  A comparison of travel times are noted in Table 15.

 External Trips

Added to the matrix were trips traveling through the study area defined as External-External trips (E-E).  The linkages between external stations were checked by the equations suggested in the Quick Response Manual NCHRP 365 [7], which relied on an estimate of functional classification, AADT and percent trucks. With limited linkages in the Huntington Metropolitan area, these equations

Table 15 Average Trip Lengths (min.)

	O-D Survey 60’s	1972 Model**	1990 Model**	Ashland* 2002	2002° Survey
HBW	13.2	13.1	20.75	20.976	16.5
HBO	10.6	10.6	18.71	19.465	15.4
NHB	10.1	10.1	15.66	20.364	13.3
CMV	9.5	9.7	---	---	13.3
Ext.	19.9	---	---	---	---
School	8.5	7.2	15.90	---	19.5
Overall	11.3	10.2	17.86°	20.00°	15.0
Ref.	[3]	[4]	[1]	[2]

 

*Includes Int.-ext. and terminal times

**Int.-Int. only.  Includes terminal times

°Calculated as weighted average

proved to be unreliable.  Therefore, estimates were based on local knowledge and bridge surveys data provided by Sam Granato of the Ohio Department of Transportation.  The resulting external-external linkages were noted in Table 16.  The external-external trips were designated as a separate table and combined with the internal-internal and internal-external trips to represent an all “travel trip matrix.”

Table 16 External-External Matrix Daily Two-Way Volumes

External Station	E-E		ADT
US52W	9001 -	9006 9011 9020 9017	15 16 112 182
WV 2 E	9007 -	9005	4
I64 E	9008	9001 9017 9020 9025	39 44 1101 4
US23 S	9017 -	9005 9025 9026	26 21 231
I64 W	9020 -	9005 9017 9026 9027	110 219 58 13
KY8 W	9025 -	9026 9027	3518 21
US23 N	9026 -	9024	65
TOTAL			5799

 

 

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MODE CHOICE AND 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

 

TIME OF DAY ANALYSIS 

      The Huntington model was utilized for a 24 hour or daily travel analysis, therefore time of day factors were not applied.  If in future applications time of day analysis are desired, a time of day distribution (H-Rates File) was developed by Sam Granato of the Ohio Department of Transportation.

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TRAFFIC ASSIGNMENT AND VALIDATION

      The final step of the four step travel demand modeling process was traffic assignment.  Before application, the model needs to be validated.  The results of the validation process was based on traffic assignment.  The assignment process involved a method of successive averages to reflect capacity restraint assignment procedures.  The BPR global information included:

 

      Travel Time Step Size = 1.0

      Base Traffic Multiplier = 1.0

      Actual Speed Multipler = 1.0

      Free Speed Multipler = 1.15

Opposite Direction Factor = 0.4

            In this sections statistics are presented on the validation process and comparisons of the simulated volumes to recommended tolerances.  Validation involves comparing average daily traffic (ADT) collected from field counts against ADT values generated by the model for the base year.  Counts for 580 links were provided by the Ohio Department of Transportation, West Virginia Department of Transportation, and Kentucky Transportation Cabinet.  Additional checks were made for vehicle-miles of travel (VMT) by functional class.  Estimates of VMT were provided by Sam Granato of the Ohio Department of Transportation.  Over 146 assignment iterations were conducted to validate the base your model.

 

 

            Table 17 provides the validation  statistics for the road links by ADT volume range.  The results are presented by the Percent Root Mean Square (PRMS) between the ground counts and simulated counts.  The PRMS was calculated as follows.

RMS =

PRMS =

X_gc = total synthetic volume

X_ta = total ground counts

N = number of observations (links)

X_gc = average of ground counts

            The PRMS gives greater weight to larger errors than small ones and weights positive and negative errors the same.  The overall Percent PRMS was found to be 43.1 percent.  Additionally as part of validation four screenlines were established as follows:

Screenline 1 = WV-OH Bridge Crossings (US52 Bridge, WV 527 Bridge, WV106 Bridge)

Screenline 2 = KY-OH Bridge Crossings (KY10 Bridge, Ironton Bridge, Ashland Bridge)

Screenline 3 = WV-KY Bridge Crossings (US60 Bridge, I-64 Bridge)

Screenline 4 = Wayne/Cabell Boundary (Adams/US60, I-64, WV152, Madison Ave.)

 

            Table 18 contains comparisons between the screenline counts and simulated traffic.  Table 19 provides validation of VMT by functional classification system.

TABLE 17 PRMS By ADT VOLUME GROUPS

Total ADT	Model	Tolerance
0 – 999	95.9%	72.3%
1,000 – 2,499	82.9	57.8
2,500 – 4,999	54.5	48.9
5,000 – 9,999	30.5	40.9
10,000 – 19,999	28.6	33.9
720,000	20.2	27.7

TABLE 18 SCREENLINE COMPARISONS 

Screenline	Location	Model	Ground Count	% Diff.
1	US52 WV527 WV106 Total	22,851 14,067 15,563 52,481	22,000 15,000 16,500 53,500	-1.9
2	KY10 Ironton Ashland Total	8,238 12,059 32,003 52,300	8,300 13,063 32,928 54,291	-3.7
3	US60 I-64 Total	12,295 23,759 36,054	13,710 24,900 38,610	-6.7
4	Adams/US60 I-64 WV152 Madison Ave. Total	8,135 33,060 17,748 13,769 72,712	14,000 30,100 16,000 9,400 69,500	+4.6
Bridges		140,835	146,401	-3.8
Total		213,547	215,901	-1.1

 

Screenline 1 = WV-OH Bridge Crossings (US52 Bridge, WV 527 Bridge, WV106 Bridge)

Screenline 2 = KY-OH Bridge Crossings (KY10 Bridge, Ironton Bridge, Ashland Bridge)

Screenline 3 = WV-KY Bridge Crossings (US60 Bridge, I-64 Bridge)

Screenline 4 = Wayne/Cabell Boundary (Adams/US60, I-64, WV152, Madison Ave.)

 

TABLE 19  VMT Comparisons  

FC-Rural	Model	Required*	Percent Difference	Req’d Percent Difference
1	636,809	607,342	+4.9%	7.0%
2 6	1,121, 797	1,019,080	+10.0%	10.0-5.0%
7 8 9	1,930,674	1,828,275	+5.6%	25.0%
Total	3,689,262	3,454,697	+6.7%
FC-Urban
11 12	1,133,703	1,187,906	_4.5%	7.0%
14 16	1,621,403	1,928,727	-15.9%	10.0-15.0%
17 19	900,660	774,117	16.3%	25%
Total	3,655,766	3,890,748	-6.0%
TOTAL	7,345,028	7,345,495	0.0%	3%

 

*VMT estimates provided by Sam Granato of the Ohio Department of Transportation, January 26, 2004.

 

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UPDATE NETWORK AND FUTURE YEAR 2030 TRAVEL FORECAST

            Based on ADT growth at the external stations a growth factor of 1.9 was applied to external-external stations and the external ends of internal-external trips.  External trips were distributed by trip purpose as presented in NCHRP 365 [7] and were: 25% HBW, 50% HBO, and 25% were NHB.  Future year socio-economic data was extrapolated from a number of sources including:

·        Huntington-Ironton Area – The year 2025 Long Range Transportation Plan [1].

·        Ashland Travel Model [2].

·        Update of Cabell County, Wayne County and Lawrence County TAZ-by KY Staff.

            The following networks changes were complete:

From the HIATS Long Range Transportation Plan for 2025 Document (chap. 8) [1]:

·        Changed Hal Greer from 12^th Ave. (where TAZ 164 intersects) to Washington Blvd approach codes changed to all end in “2” instead of “R” or “U” to account fro a new center turn lane.

·        Changed sat. flow rate on 8^th Ave. from 24^th St. (where TAZ 155 intersects) to 31^st St/US60 from 1385 to 2770 and from 2200 to 4400 to account for going from 2 lanes to 4 lanes.

·        Changed sat. flow rate on Merrick Creek/CR 19 from WV2 to I-64 from 2200 to 4400 to account for going from 2 lane to 4 lane.

·        Changed approach code on Spring Valley/CR7 from WV75 to James River to end with “2” instead of “U” to account for a new center turn lane.

·        Changed sat. flow rate on WV10 from Davis Creek to Madison Creek from 1700 to 3400 and 1385 to 2770 to account for going from 2 lane to 4 lane.

  ·        Changed sat. flow rate on WV152 from south of TAZ 228 to WV75 from 1700 to 3400 to account for going from 2 lane to 4 lane.

·        Change sat. flow rate on US60 from I-64 Exit 15 to Cabell County Border from 1385 to 4155, 1490 to 4470, 2980 to 4470, 3400 to 5100, and 3800 to 5700 to account for going from 2 or 4 lanes all going to 6 lanes.

·        Changed sat. flow rate on I-64 from US60 (Exist 15) to Cabell County Border from 4800 t0 7200 to account for 4 lane to 6 lane.

·        Changed sat. flow rate on 1^st St. (in Huntington) from 4^th Ave. to 7^th Ave. from 1385 to 2770 to account for going from 2 lane to 4 lane.

·        Changed sat. flow rate on US52 from I-64 (WV Exit 1) to southern Wayne County Border from 1800 to 3600, 2000 to 400, and 2200 to 4400 to account for going from 2 lane to 4 lane.

·        Changed sat. flow rate on OH93 from just south of TAZ 41 to northern Lawrence County Border from 1700 to 3400 to account for going from 2 lane to 4 lane.

·        Changed approach code on OH141/Campbell from US52 to OH21/217 to end with “2” instead of “R” or “U” to account for a center turn lane.

·        Added Chesapeake Bypass (Alt20a.1.dta) to come up with the geometry, interchange locations and layouts, and the input data.  Used 4000 sat. flow rate per direction and 55 mph free speed.  Interchanges located at OH243 north of Bent creek Rd. (c-118), WV106 Bridge extension, OH77, Big Paddy Rd. north of OH243, and OH7.

·        Added new bridge across Ohio River from WV2/CR19 intersection to eastern terminus of the new Chesapeake Bypass.

·        Signalized the intersections at the OH141 and US52 interchange.  Assumed a 70 sec. cycle length.

·        Changed sat. flow rate on US52 WB (only) at the Ashland Bridge (4 links total) from 4800 to 720 to account for an additional lane.

·        Signalized interchange of US52 and Marion Pike/OH243.  Assumed 70 sec. cycle length.

·        Replace cloverleaf at US52 and OH93 interchange with a diamond.

 From the Cabell County Land Use Report (p.22ft) [1]

·        Changed sat. flow rate on WV10/16^th St. from south of I-64 to Davis Creek from 1400 to 2800 and 1700 to 3400 to account for 2 lane to 4 lane.

From the Ashland Report (p. 47^th) [2]

·        Change approached code on 13^th St./US60 from Pollard/Oakview to Sycamore St. (intersection of TAZ 1042) to end with “2” instead of “U” to account for a center turn lane.

·        Changed approach code on Pond Run Rd. from US23/Seaton to Raceland Rd. to end with “2” instead of “U” to account for a center turn lane.

·        Changed I-64 WB off ramp onto KY180 from cloveleaf to diamond.
 

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References

 

1.      Huntington-Ironton Area Transportation Study.  The Year 2025 Long-Range Transportation Plan.  KYOVA Interstate Planning Commission Huntington, West Virginia.  February 2002.

2.      Ashland Travel Model.  The Corradino Group.  Louisville, Kentucky.  August 2002.

3.      HAIAT’s Phase II Future Travel and Highway Needs.  Wilbur Smith and Associates, New Haven, CT.  May 1971.

4.      Huntington-Ashland-Ironton Area Transportation Study 1973 Major Review and 2000 Plan Update.  HAIATS Technical Advisory Committee.  January 1975.

5.      Validation of Huntington-Ironton Area Transportation Study Travel Forecasting Model for the Base Year of 1990.  KYOVA Interstate Planning Commission.  Huntington, West Virginia.  July 1998.

6.      Sosslau, A., et al., “Quick Response Urban Travel Estimation Techniques and Transferable Parameters:  Users Guide.”  NCHRP 187,  Transportation Research Board, Washington DC, 1978.

7.      William Martin and N. McGuckin.  “Travel Estimation Techniques vs. Urban Planning.”  NCHRP 365. Transportation Research Board.  Washington, DC, 1998.

8.      Web-site National Personal Transportation Study. US Department of  Transportation. Washington DC, 1995.

9.      Introduction to Urban Travel Demand Forecasting.  National Highway Institute Course.  Federal Highway Administration.  Washington, DC.  March 2002.

10. Wegmann, F, et al. Household Survey and Transferable Parameters for Travel Demand Forecasting in Tennessee, Center for Transportation Research, University of Tennessee, Knoxville, Tennessee, March 2004.

11. Clarksville Urbanized Area Travel Demand Model – Model Documentation and Users Guide.  Kimley-Horn and Associates, Memphis, Tennessee, July 2001.