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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.
| 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 |
| 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):
- 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
- 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.
- 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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