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Evaluation of Highway Performance Measures for a Multi-Study Corridor - A Pilot Study

5.0 Design Report: Condition Indicator Display Capability in ICAT

This section contains the design report for incorporating the display of bridge and pavement condition information into the ICAT web application (WebCAT). The goal of this task was to provide users with the capability to use the WebCAT map interface to select a section of Interstate 95 in Virginia, Maryland, and/or Delaware and to overlay information representing bridge and pavement condition measures.

5.1 WebCAT Environment

Geodatabase

The ICAT geodatabase was built using ESRI's ArcGIS Server 9.3. ArcGIS Server includes SDE (Spatial Database Engine), which is used to spatially enable a relational database management system (RDBMS). For ICAT, the RDBMS is Microsoft SQL Server 2005. SQL Server and SDE together form a geodatabase, which holds all information displayed within WebCAT.

Web Application

The WebCAT web application is an Adobe Flex program that uses the ESRI Flex Map application programming interface (API) to communicate with ArcGIS Server. ESRI developed a sample web application called FlexViewer, which is written using Adobe Flex and the ActionScript programming language. The WebCAT web application is a customized version of the FlexViewer web application.

5.2 WebCAT Design

The application framework used for the WebCAT provides a standard architecture for incorporating new geographically tagged information. No custom elements or programming were required for this effort. The following steps were used to add map layers containing bridge and pavement condition data:

  • As described in Section 3.4, common data structures were defined for the bridge and pavement data. These structures were created as tables in the SDE geodatabase. The bridge table contains one record for each bridge and the pavement table contains one record for each pavement section. Each record in these tables includes:
    • Sufficient information to position the bridge or pavement section on the ICAT network;
    • A set of condition measures associated with the bridge or pavement section; and
    • Any other relevant information associated with the bridge or pavement section. For example, the bridge table contains a subset of the NBI items for each bridge.

    A database structure for bridges is shown in Table 5.1 and a structure for pavement is shown in Table 5.2. These database structures also include columns that contain calculated performance measures.

  • ArcMap, part of ArcGIS desktop, was used to create a set of map services. A map service defines:
    • The data to be included (e.g., pavement sections);
    • A condition measure to be categorized (e.g., IRI);
    • A method for categorizing the condition measure (e.g., by value range); and
    • Display characteristics for the condition measure categories (e.g., lines of different widths or colors).

    The specifics of these map services (i.e., the condition measures and the ways in which they are categorized) are documented in Section 4.3.

  • ArcCatalog, another part of ArcGIS desktop, was used to publish the map services to ArcGIS Server.
  • The WebCAT configuration files were updated to incorporate the map services as additional data layers into the WebCAT application.
Table 5.1 Bridge Database Structure
Column Name Data Type Description
State CHAR(2) State Code
County Code CHAR(3) County Code received from state
BRKEY VARCHAR(16) Bridge Key
Route ID VARCHAR(40) Route ID received from state or calculated from state values
ON_UNDER NUMBER(1) Record Type
KIND_HWY NUMBER(1) Route Signing Prefix
LEVL_SRVC NUMBER(1) Designated Level of Service
ROUTENUM CHAR(5) Route Number
DIRSUFFIX CHAR(1) Directional Suffix
ROADWAY_NAME VARCHAR(25) Roadway Name
KMPOST NUMBER(4,3) Kilometer Point
FACILITY VARCHAR(18) Facility Carried
LOCATION VARCHAR(25) Location
FEATINT VARCHAR(25) Features Intersected
LATITUDE NUMBER(8) Latitude
LONGITUDE NUMBER(9) Longitude
CRIT_FEAT CHAR(1) Critical Feature
TOLLFAC NUMBER(1) Toll
FUNCCLASS NUMBER(2) Functional Class
LANES NUMBER(4) Lanes On/Under
ADTTOTAL NUMBER(6) Average Daily Traffic
ADTYEAR NUMBER(4) Year of Average Daily Traffic
TRAFFICDIR NUMBER(1) Direction of Traffic
TRUCKPCT NUMBER(2) Average Daily Truck Traffic
ADTFUTURE NUMBER(6) Future Average Daily Traffic
ADTFUTUREYEAR NUMBER(4) Year of Future Average Daily Traffic
DECK_AREA NUMBER(10,5) Deck Area
TEV_WEIGHT NUMBER(10,1) Total Element Value Weight (entire bridge)
CEV_WEIGHT NUMBER(10,1) Current Element Value Weight (entire bridge)
HIX_WEIGHT NUMBER(3,1) Health Index (entire bridge)
TEV_WEIGHT_DECK NUMBER(10,1) Total Element Value Weight (deck only)
CEV_WEIGHT_DECK NUMBER(10,1) Current Element Value Weight (deck only)
HIX_WEIGHT_DECK NUMBER(3,1) Health Index (deck only)
TEV_WEIGHT_SUPER NUMBER(10,1) Total Element Value Weight (superstructure only)
CEV_WEIGHT_SUPER NUMBER(10,1) Current Element Value Weight (superstructure only)
HIX_WEIGHT_SUPER NUMBER(3,1) Health Index (superstructure only)
TEV_WEIGHT_SUB NUMBER(10,1) Total Element Value Weight (substructure only)
CEV_WEIGHT_SUB NUMBER(10,1) Current Element Value Weight (substructure only)
HIX_WEIGHT_SUB NUMBER(3,1) Health Index (substructure only)
DKRATING CHAR(1) Deck Rating
SUPRATING CHAR(1) Superstructure Rating
SUBRATING CHAR(1) Substructure Rating
CULVRATING CHAR(1) Culvert Rating
STRRATING CHAR(1) Structural Rating
NBI_RATING CHAR(1) NBI Rating
SUFF_RATE NUMBER(3,1) Sufficiency Rating
SUFF_PREFX CHAR(1) Sufficiency Rating Prefix
SR_HIX_DIFF NUMBER(10,1) Difference Between SUFF_RATE and HIX_WEIGHT
Table 5.2 Pavement Database Structure
Column Name Data Type Description
State CHAR(2) State Code
County Code CHAR(3) County Code received from state (only for MD and VA)
Route ID VARCHAR(40) Route ID received from state or calculated from state values
Road Name VARCHAR(100) Road Name received from state (only for DE)
Beg MP NUMBER(7,3) Beginning Milepoint
End MP NUMBER(7,3) Ending Milepoint
Length NUMBER(7,3) Segment Length (only for VA)
IRI_L NUMBER(3) IRI Left (only for DE and VA)
IRI_R NUMBER(3) IRI Right (only for DE and VA)
IRI_Avg NUMBER(3) IRI Average
T_CR1_LF NUMBER(5) Transverse Cracking Severity 1 (only for VA)
T_CR2_LF NUMBER(5) Transverse Cracking Severity 2 (only for VA)
L_CR1_LF NUMBER(5) Longitudinal Cracking Severity 1 (only for VA)
L_CR2_LF NUMBER(5) Longitudinal Cracking Severity 2 (only for VA)
L_JT1_LF NUMBER(5) Longitudinal Lane Joint Severity 1 (only for VA)
L_JT2_LF NUMBER(5) Longitudinal Lane Joint Severity 2 (only for VA)
RT_CR1_LF NUMBER(5) Reflective Transverse Cracking Severity 1 (only for VA)
RT_CR2_LF NUMBER(5) Reflective Transverse Cracking Severity 2 (only for VA)
RT_CR3_LF NUMBER(5) Reflective Transverse Cracking Severity 3 (only for VA)
RL_CR1_LF NUMBER(5) Reflective Longitudinal Cracking Severity 1 (only for VA)
RL_CR2_LF NUMBER(5) Reflective Longitudinal Cracking Severity 2 (only for VA)
RL_CR3_LF NUMBER(5) Reflective Longitudinal Cracking Severity 3 (only for VA)
A_CR1_SF NUMBER(5) Alligator Cracking Severity 1 (only for VA)
A_CR2_SF NUMBER(5) Alligator Cracking Severity 2 (only for VA)
A_CR3_SF NUMBER(5) Alligator Cracking Severity 3 (only for VA)
PA_WP_SF NUMBER(6) Patching Area - Wheel Path (only for VA)
PA_NWP_SF NUMBER(6) Patching Area - Nonwheel Path (only for VA)
POT_NO NUMBER(3) Pothole Count (only for VA)
DELAM_SF NUMBER(5) Delamination Area (only for VA)
BLEED1_SF NUMBER(5) Bleeding Severity 1 (only for VA)
BLEED2_SF NUMBER(5) Bleeding Severity 2 (only for VA)
RUT_S_AVG NUMBER(5,2) Average Rut Depth - Straight Edge (only for VA and MD)
RUT_W_AVG NUMBER(5,2) Average Rut Depth - Wire Method (only for VA and MD)
LDR NUMBER(3) Load Distress Rating (only for VA)
NDR NUMBER(3) Nonload Distress Rating (only for VA)
CCI NUMBER(3) Critical Condition Index (only for VA)
Latitude Start NUMBER(15,10) Latitude at start of segment (only for VA)
Longitude Start NUMBER(15,10) Longitude at start of segment (only for VA)
Latitude End NUMBER(15,10) Latitude at end of segment (only for VA)
Longitude End NUMBER(15,10) Longitude at end of segment (only for VA)
OPC NUMBER(6,2) Overall Pavement Condition (only for DE)
IRI Condition NUMBER(1) IRI Condition Index (only for MD)
Rut Count NUMBER(5,2) Rut Count (only for MD)
Rut Condition NUMBER(1) Rut Condition Index (only for MD)
Friction Number NUMBER(5,2) Friction Number (only for MD)
Friction Condition NUMBER(1) Friction Condition Index (only for MD)
Cracking Index NUMBER(5,2) Cracking Index (only for MD)
Crack Condition NUMBER(1) Cracking Condition Index (only for MD)
OPC_VS_CCI NUMBER(6,2) Difference Between OPC and CCI
User Interface Changes

Integration of bridge and pavement condition measures into WebCAT manifests itself in three places (refer to Figure 5.1):

  1. Additional data layers are available within the WebCAT data toolbox. This toolbox is displayed by selecting "WebCAT Data" under the Map menu item. These additional data layers correspond to the map services described previously.

    Under the heading "Bridges (Mid-Atlantic)," options represent the ways in which bridges are categorized. For example, one option is "Health Index - Overall," which categorizes bridges based on a set of health index ranges. Each category is represented visually using icons of different colors.

    A heading called "Pavement (Mid-Atlantic)" contains a set of options by which pavement sections are categorized. For example, one option is "IRI," which categorizes pavement sections based on a set of IRI ranges. The line representing each pavement section is shown using a different width based on the IRI category for that section.

Figure 5.1 WebCAT User Interface
This is a sample screenshot of the modified WebCAT user interface. The WebCAT is a web-based system that uses a map interface onto which one or more data set may be layered. This screen shows the Interstate 95 corridor from the southern border of Virginia to the northern border of Delaware using a street map view. I-95 is overlaid with a red line, the thickness of which represents the International Roughness Index for the particular road segment. On top of this line is set of red diamonds, each one representing a bridge. The standard WebCAT menu, with the title Multi-State HPM, is displayed in the upper left corner. The following WebCAT control panels are displayed on the right side of the screen: at the top, the WebCAT data panel with the Bridge (Mid-Atlantic) and Pavement (Mid-Atlantic) layer groupings checked; in the middle, the WebCAT legend; at the bottom, the WebCAT identify panel with the Bridges (I-95) layer selected.

  1. Each map service also appears as an option in the Identify toolbox. This toolbox is displayed by selecting "Identify" under the ID menu item.

    Using the Identify tool, users can click on a specific bridge or pavement section to see detailed information. The information is pulled from the bridge or pavement tables in the geodatabase. This process displays most of the data available for the selected item, excluding elements used only for internal purposes.

  2. The legend was updated to include information on the different condition measure categories. This information helps in interpreting the visual information contained in each map layer. Note that the legend currently is a static image and contains information for all map layers. The user must manually locate the specific portion of the legend that applies to the layer that is displayed.
Issues

Data for specific bridges and pavement sections may be missing. This could manifest itself in one of two ways:

  • The entire bridge/section is missing from the data table - in this case, the object would not appear in any of the data layers created for this project; or
  • The bridge/section is available but a particular performance measure could not be calculated - in this case, the object would not appear only when certain data layers are selected.

Section 4.3 discusses gaps in the base data and how these affect the performance measures calculated from these data as well as the display of the different layers.

When multiple data layers are selected, they are drawn on the base map in order from bottom to top. Given that there are a limited number of visual options that may be applied to the different performance measure categories, it would be easy to select two data layers where the second completely obscures the first. Section 4.3 identifies the visual display characteristics used for each performance measure. It is up to the user to either display one measure at a time or to select measures that are visually compatible.

For practical reasons, the number of data layers created in the WebCAT was limited to the most interesting condition measures identified during Task 3. In total, eight layers were created using bridge data and 10 layers using pavement data.

5.3 Web-Based Training

FHWA personnel participated in a web-based demonstration and training session on March 9, 2010 for the revised WebCAT. This training covered the process of using WebCAT features as well as the content and display characteristics of each map layer. Following this session, some changes were made to the WebCAT system to address comments received, including the creation of five additional map layers. FHWA personnel then used this system during a two-week test to conduct their own analyses.

The revised WebCAT currently is deployed on a CS server and will remain available for a limited time consistent with policies to be established between the I-95 Corridor Coalition and CS. The University of Maryland is scheduled to take over hosting of the WebCAT at some future time. When this transition occurs, the revised WebCAT developed for this project also may be moved to the University of Maryland.

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Updated: 06/18/2012