SPATIOTEMPORAL VISUALIZATION OF UNIT
PRICES OF MAJOR COST ITEMS OF
TRANSPORTATION PROJECTS ACROSS IOWA
USING GEOGRAPHIC INFORMATION SYSTEMS
(GIS)
DEEPANSHI JAIN
GIS CERTIFICATE CANDIDATE
MASTER OF SCIENCE CANDIDATE
DEPARTMENT OF CIVIL, CONSTRUCTION, AND ENVIRONMENTAL ENGINEERING
CRP 595
GIS ADVISOR: DR. KEVIN KANE

AGENDA
• Motivation/Background
• Introduction
• Research Problem
• Methodology
• Spatial Questions
• GIS Tool: Spatial Analyst
• Exploring Data
• Quantity effect considered
• Results
• Creating precise predictions
• Time effect considered
• Evaluation: Cross validation
• Conclusions
• Further analysis

BACKGROUND
• Construction industry is driven by time and cost.
• Highway construction is a costly investment.
• Funding sources are limited.
• Efficient utilization of funds requires
“better estimation”.
• Estimation department strives for accuracy in estimating unit price.
• Closer the unit price == better cost estimate.
Iowa DOT (http://www.iowadot.gov/program_management/Final%202014-
2018%20Highway%20Program%20Brochure.pdf)

INTRODUCTION
• Iowa Department Of
Transportation Projects
• Hot Mix Asphalt (HMA)
Pavements across Iowa
• Identified major cost items of construction HMA Pavements:
• Asphalt Binder 64-22
• Asphalt Binder 58-28
• Hot Mix Asphalt Mixture

RESEARCH PROBLEM
• Unit price estimation using available historical bid data for various locations.
• New project == New location
• Adjustment of unit price for new location??
• Exploring inbuilt tools in GIS to assist estimator to quantify unit price

METHODOLOGY
Historical Bid Data
Identify Major Cost Items
Explore Data
Spatial Interpolation Techniques
Identify better interpolation Technique and parameters

POSSIBLE FACTORS AFFECTING UNIT PRICE
• Location of project
• Quantity
• Time
• Location of Asphalt plant
• Labor Cost
• Population Density

SPATIAL QUESTIONS
• How are unit prices of Asphalt binder 64-22 related to location ?
• How quantity of material affects the unit price spatially?
• Does asphalt binder plant location have any effect on unit prices?
• Does Urban /rural location of projects have any effect on prices?
• Does population density have any effect on unit price?

ARCGIS GEOSTATISTICAL ANALYST AND SPATIAL
ANALYST
• Compliment each other.
• Geostatistical analyst has some additional features like:
• exploratory data analysis
• More statistical models and tools
• Variety of surfaces e.g. prediction, probability, etc.
• Spatial analyst has some additional features like:
• Map algebra
• Data conversion
• Combinational operators

INTERPOLATION METHODS
Point
Interpolation
Kriging
Natural
Neighbor
Spline
Spatial
Interpolation
Methods
Trend
Methods
Inverse
Distance
Weighting
Topo
to Raster
Geostatistical
Techniques
Deterministic
Techniques
Spatial
Interpolation Methods in GIS

GIS PROCESS
• Explore the data
• Findings
• Parameters
• Predictions
• Cross Validation

2011

2012

2013

2014

FINDINGS
• Histograms: Not symmetrical
• Normal Quantile Plot: Way off from normality
• Trend Analysis: A order two polynomial directional trend observed for data of years 2011, 2012, 2014. No particular trend observed for 2013.
• Kriging model will be very difficult to fit.

INVERSE DISTANCE WEIGHTING (IDW)
• Simpler to apply (Henley, 1981)
• Applicable for dataset of small sizes (Rasmunsen- Rhodes and Mayers, 1993)
• Flexible to model the variables with a trend or anisotropy present (Tomczak,
1998)
• Bette interpolation technique for Construction cost index (Zhang, 2013)

AVERAGE ERROR FOR ASPHALT
BINDER 64-22 IN VARIOUS CASES
Cases
Inverse Quantity
No Quantity
Quantity
2011
19.17
3.505
-11.075

AVERAGE ERROR FOR ASPHALT BINDER 64-
22 IN VARIOUS CASES
Cases
Inverse Quantity
No Quantity
Quantity
2012
-5.414
-2.05
-2.39

AVERAGE ERROR FOR
ASPHALT BINDER 64-22 IN
VARIOUS CASES
Cases/Year
Inverse Quantity
No Quantity
Quantity
2013
4.7655
5.59
13.5427

AVERAGE ERROR FOR ASPHALT
BINDER 64-22 IN VARIOUS
CASES
Cases/Year
Inverse Quantity
No Quantity
Quantity
2014
5.370608
0.938
-3.044

RESULTS
Image Source:http://quoteimg.com/unit-elastic-demand-curve/2/
How quantity of material affects the unit price spatially?
• General assumption that unit price decreases with quantity is not true in case of asphalt binder 64-22
• Using IDW without any quantity effect gives better results in terms of least error .

RESULTS
ASPHALT BINDER 2011-
2014 USING IDW
How are unit prices of Asphalt binder 64-22 related to location ?
• For each year the relationship with location shows repeated high cost zones and repeated low cost zones.

INFLATION CONSIDERED
• All year data was extrapolated to 2014 by using the developed average inflation rate of unit price.
• More data points
• Better distribution
• Better interpolation result

ASPHALT BINDER 64-22 ,
INFLATION INCLUDED
• Zero average standard error
•
More data points, distributed better

ASPHALT PLANT
LOCATION
Does asphalt binder plant location have any effect on unit prices?
• Low cost regions have more asphalt plants located nearby.
• Transportation cost maybe one of the major component of unit price.

CONCLUSIONS
• IDW is most suitable for Asphalt Binder 64-22 data.
• Considering quantity, and 1/quantity as weights shows that better interpolation results are obtained when no weight is given.
• By increasing the number of data points IDW results improved.
• Transportation cost maybe a major component of unit price of asphalt binder
64-22.

FURTHER ANALYSIS
• Analysis of interpolation results using:
• Average weekly Labor cost for county.
• Population density of Iowa

THANK YOU!
Questions?