DESCRIPTION

 

DATA LAYER NAME:           FDOT_NAB_GDB.mdb

DESCRIPTION:                      Personal of Florida Department of Transportation (FDOT) Noise Abatement Barriers

TYPE:                                      Feature classes (lines / points)

SCALE:                                   1:2,500

DATUM:                                 GCS North American 1983, HARN

PROJECTION:                        Albers Conical Equal Area (Florida Geographic Data Library)

MAP UNITS:                          Meters

 

PROVIDING ORGANIZATION

 

AGENCY:                               Florida Department of Transportation

                                                Environmental Management Office

CONTACT PERSON(S):        Mariano Berrios

AGENCY DATA NAME:       Noise Abatement Barriers

 

DESCRIPTION OF SOURCE MATERIALS

SOURCE TITLE(S):                FDOT June 2000 Noise Barrier Status Report (Spreadsheet)

Global Positioning Systems (GPS) via Trimble GeoXT with GPS correct for real-time post-processing

GlobeXplorer’s high resolution imagery via ArcWeb Services

SCALE:                                   1:2,500

DATUM:                                 NAD1983

MAP PROJECTION:              Albers Conical Equal Area

MEDIA OF SOURCE:            ArcWeb Services

CONDITION OF MEDIA:     Good

SOURCE MATERIALS:        

(DATE)                        :           Spreadsheet (Attributes) and GPS – May-Nov 2004

                                                GlobeXplorer’s High Resolution Aerials - 2004

UPDATE SCHEDULE:           CUES is available upon request for contract services

 

CREATOR OF DATA LAYER

 

AGENCY / ORGANIZATION:          Center of Urban and Environmental Solutions (CUES)

                                                            Florida Atlantic University

                                                            111 East Las Olas Blvd, Suite 709

                                                            Fort Lauderdale, Fl 33301

                                                                                                                                                           

UNIT / SECTION:

CONTACT PERSON:                        Christina Bryk

TITLE:                                     Research Associate

PHONE NUMBER:                             (954) 762-5255 / Fax: (954) 762-5666

WEB ADDRESS:                                http://www.cuesfau.org

 

 

 

DERIVIATON METHOD(S) FOR DATA

PRE-AUTOMATION:                        Noise Barriers were compiled based upon locational information in the FDOT - Noise Barrier Status Report, June 2000. Based upon telephone interviews and surveys, the Noise Barriers in Districts 1, 2, 5, and 7 were identified. District 4 Noise Barriers were collected via GPS and provided as a line feature class and point feature class within a personal geodatabase from District 4. District 6 collected the start and end nodes for each wall via GPS and provided the information as a point feature in Shapefile format.

OPERATING SYSTEM:                     Windows XP

GIS / MAPPING SOFTWARE
AND VERSION:                                 ArcGIS (ArcEditor) 9.0, Service Pack 3

METHOD OF AUTOMATION:         GPS for primary automation and On-Screen digitizing

 

RESOLUTION OF
AUTOMATION:                                 GlobeXplorer’s ‘Citipix/Digital Ortho’ - six-inch resolution

and in 24-bit color

INITIAL DATA OF
AUTOMATION:                                 May 2004 onward

UPDATE SCHEDULE:                       To be Determined by FDOT

SIZE OF DIGITAL FILE:                    Approximately 43.3 megabytes

FORMAT OF DIGITAL FILE:            Personal Geodatabase (ArcGIS 9.x)

 

EXPLANATION OF PROCEDURES USED TO CREATE DATA:
Excerpt from Final Report, Conversion of the Statewide Noise Barrier Inventory

Into a Spatially Referenced Geodatabase, prepared for Office of Environmental Management, FDOT, April 2005.

Primary Data Collection - GPS

In late May 2004, the Center for Urban and Envionmental Solutions deployed a field team to ground-truth the original 30 noise abatement walls in the June 2000 Report.  Utilizing a Trimble GeoXT with GPS correct for real-time post-processing, the field team collected GPS information to verify the location of these barriers.

During the GPS field work, three (3) new walls were identified in District 1 along the I-4 Corridor, the GPS information was collected for these walls as well. Once research staff confirmed these were owned by FDOT, they were included into the Statewide Noise Abatement Geodatabase. GPS coordinates were collected by the research field team for 33 noise abatement walls.  District 4 and District 6 indicated that they would be initiating their own GPS collection during the summer and fall of 2004. Rather then replicate this effort, CUES coordinated with these two districts to obtain the completed GPS information and import it into the Statewide Geodatabase. However, approximately seven walls were not included in these two Districts inventories. Therefore, CUES field team used GPS to collect wall information mainly for the Sawgrass Expressway and the Florida Turnpike. Overall GPS coordinates were collected for 40 walls by CUES.

 

The internal setting of the GeoXT’s GPS were set to ensure the highest possible accuracy. The settings utilized are as follows:

 

Each noise barrier wall in the region was surveyed to obtain both spatial, attribute and photographic information necessary for the project. Upon arrival to the particular barrier wall, the team would investigate the following conditions before undertaking the survey:

Upon arrival to the location, traffic volume was determined by the amount of traffic traveling adjacent to the wall of interest. The estimated volume determined whether it was judged safe for a foot survey or required use of a vehicle. Hard hats and florescent safety vests were worn at all times while conducting the surveys.

Numerous barrier walls surveyed had large swaths of vegetation planted next to them. Major types of vegetation included: Sable Palm trees, Sea Grape and various other bushes.  These vegetation lines often followed the length of the given wall an ranged on an average from 10-75 feet. Since many of the walls had some type of vegetation, an offset was incorporated into the survey. Generally all surveys were done on an average of 20 feet in front of the wall. Many of the walls not only had a vegetation line in front but also a layer of standing water. This situation occurred in areas where the walls possessed a gully or depression directly in front of the vegetation line. In many situations, the accumulated water actually formed a small linear wetland including typical wetland flora and fauna which included unfortunately high concentrations of biting insects. If these water bodies existed, the offset was increased to account for the additional obstacle so that the survey could continue. Other barriers to the survey included manmade structures such as tollbooths, embankments, bridges and narrow walks. If such obstacles were encountered, the situation was noted in the attribute table and the offset increased as needed.

GPS is a line of sight technology which relies on the ground based receiver the ability to have a clear and unobstructed line of sight to the GPS satellites. noise barrier walls provide a unique problem in that they can obstruct half of the sky depending on how close the survey is conducted to them. Due to this fact, an offset was also needed to obtain the best possible satellite lock. GPS uses a measurement called PDOP (Position Dilution of Precision) to indicate accuracy. To ensure high accuracy GPS positioning, it is recommended that the PDOP value be less than 6. During all wall surveys, PDOP was monitored very closely and any measurement greater than 6 was resurveyed.

 

Once the Noise Barrier Wall was cleared to survey, the walking team member would activate the Mobile GIS/GPS unit and begin logging the poly-line feature. At the beginning of the logging, an initial starting coordinate would be relayed to the vehicle team member for input into handwriting log. If a walking Survey was done, the survey team member would walk the length of the wall with the vehicle team member following along to provide a look out for traffic. At the halfway point of the survey, the walking team member would again call out the coordinate of the middle of the wall to the vehicle team member. Once the entire length of the wall had been traversed, the walking team member would stop the logging and fill in the custom input form in the ArcPad software. Digital photos were also taken at each survey location.

After each wall was surveyed, the team would back up the data on the GeoXT mobile device and then download the data onto a laptop computer. This procedure was completed at the location incase data was lost and the survey would have to be redone. Once back at the office, all data for that day was downloaded onto the project server to be used by the GIS section.

Acquisition from Individual Districts of Walls in GIS format 

According to interviews conducted during this project among FDOT personnel, at the time of interviews, District offices were not maintaining an inventory of their noise barriers in GIS. However, in the summer and fall of 2004, two District offices used GPS technology to store their noise abatement walls in GIS.

District Four utilized GPS to store both the point (begin/end points) and line feature classes representing 95 noise abatement walls. District 4 provided the research team with their personal geodatabase. Next, the point and line feature classes were merged and spatially projected into the Statewide Geodatabase. District 4 also created a hyperlink to the photos collected during their GPS work.  This hyperlinkis included as part of the Statewide Geodatabase.

District Six utilized GPS technology to capture the begin node and end node for each wall. However, no line feature classes were created. Utilizing the GPS begin and end nodes, the research team digitized the line feature class representing the noise barriers for approximately 84 out of 96 total walls in District 6. A Trimble GeoXT was used to collect the points and linear features depicting the remaining 12 barriers.

On Screen (Heads-up) Digitizing

This spatial data collection technique, based on utilizing high quality, rectified aerial photos and other georeferenced GIS layers, was used to primarily to edit the spatial data collected through GPS for relative positional accuracy purposes. The level of accuracy of the derived dataset is taken from the initial accuracy of the digital image along with georeferenced GIS layers.

One of the challenges was to utilize aerial photos in GIS at an acceptable resolution needed to create and edit spatial features for all District offices that have noise abatement walls. The central problem is that most ortho photos in GIS are collected by county governments who collected this raster information at varying scales, different data formats (e.g. MrSID, TIF, JPEG, SDE) and/or captured at different time frames. Based upon these challenges as well as the degree of acquiring these raster features, it was decided to utilize ESRI’s ArcWeb Services.

One of ArcWeb Services offered is access to GlobeXplorer’s ‘Citipix/Digital Ortho’  which was used to perform the spatial edits required to verify and/or‘re-align’ the GPS collected data relative to scale of FDOT’s GIS base map layers. Citipix is the largest high-resolution aerial imagery dataset available online through ArcWeb Services.  Captured at six-inch resolution and in 24-bit color, Citipix is precision geo-referenced and ortho-rectified.   It covers over 7,000 cities and towns in over 73 metropolitan areas in the United States, with a total area of over 90,000 square miles.

Because of Citipix high resolution, it provided the optimal back ground layer to digitize, edit, and verify the linear features representing the walls. Using GPS points collected by District 6 which represent the begin and end nodes for each wall along with GlobeXplorer’s digital orthophotography, the line feature classes for these walls were digitized.  96 out of the 217 walls within the Statewide Geodatabase were digitized. District 6 accounts for approximately 44% of all noise barriers in the Statewide Geodatabase.

 

 

Data Verification / Quality Assurance

To verify the correctness of the georeferenced information collected (ground truthing), the research team validated nearly 70% of all noise barriers maintained by FDOT  in the field utilizing GPS technology (150 of the 217 walls). The remaining 30% of the walls were validated utilizing GlobeXplorer’s high resolution imagery. 

 

 

ATTRIBUTE DESCRIPTION

 

The Noise Abatement Barriers personal geodatabase has attributes that can be related to Roadway Characteristics Inventory (RCI) data with the ‘ROADWAY’ field. In addition, since there were numerous yet incomplete unique identifiers associated with noise barriers such as RCI, Job number, FM number, WPI number or unique identifier assigned by an individual District office, a Key Identifier was created by CUES.

 

The Key Identifier developed for this project is a combination of FDOT’s multiple unique identifiers including identifiers that distinguish each individual District office as well as the county the wall is located in. For example, a noise barrier in District 4 located in Palm Beach County would be assigned ’120409999004342017’ where [12] represents the State FIPS, [04] represents the District, and so forth, refer to table for further explanation.

 

Key Identifer

120409999004342017

Value

Width

Description

12

02

Statewide FIPS

04

02

FDOT District

099

03

County FIPS

99004

05

RCI / Job Number

3420

04

WPI

17

02

Sequence Unique ID Assigned by CUES

 

Some limitations with the unique identification number include those walls where no WPI, no FM numbers exist or was available. For example, in District 6, the research team incorporated the key identifier along with the Statewide FIPs, FDOT District number, Countywide FIPS, and Roadway Characteristic Inventory number, including the new RCI number for south-bound Interstate 95. As for District 4’s unique identifier, it is contained in the point feature class which can be linked to the line feature. Although, the WPI or FM numbers may not be included since it was not available for this geodatabase, it can be updated to it quite easily.

 

The importance of the Key Identifiers are to link together information derived from individual District offices and it should be considered by FDOT as a standard identifier for future data updates. The Key Identifiers provide users the ability to create relationships among multiple tables both within and outside the geodatabase. For example, if a District office maintains a database containing the WPI or FM numbers associated with the noise barriers, a relationship class can be generated.

 

The Key Identifier established by the research team permits a relationship between the point feature class and the line feature class to exist as well. The point feature class contains the GPS coordinates representing the begin point and end point of a wall, hyperlink to digital pictures for District 4, and District 4’s unique identifier. Therefore, if the user clicks on a line feature representing a wall within District 4, they can easily identify the unique identifier assigned to that wall by the District itself as well as any digital photos associated with the wall. One of the limitations with relating the line features to the point features is where a begin or end point overlap.

 

As for the remaining attributes, an assessment of the existing Noise Barrier Inventory was conducted by CUES as well as a review of processes and procedures related to this task. This was accomplished through surveys, interviews, and review of the existing district databases. Based upon the assessment, the following attributes were included:

 

 

 

An additional feature class representing the ‘start’ point and ‘end’ point of the walls was also stored within the personal geodatabase as a point feature class. The point feature class can be ‘related’ or ‘linked’ to the line feature class based upon the NBID which was the CUES Unique Identifier:

 

 

LIMITATION OF DATA

 

Spatial Limitations:

 

ü      Relative scale was utilized as opposed to field measurements that define absolute scale. This is not to say GPS technology was excluded, in fact during this project, nearly every barrier was identified and/or verified using a Trimble GXT. However, the X/Y coordinates collected through the use of GPS were no longer positionally aligned relative to the scale used for FDOT FGDL layers. Therefore, spatial editing was used to adjust the positional location of the barriers to align them to based upon the relative accuracy of the existing GIS layers.

 

ü      Physical Access to Noise Abate Barriers

 

o       CUES field team could not stand directly on top of the wall to collect GPS readings. Rather, the field team had to collect GPS readings near or offset of the wall location.

 

o       Traffic Volume - Upon arrival to the location, traffic volume was determined by the amount of traffic traveling adjacent to the wall of interest. The estimated volume determined whether it was judged safe for a foot survey or required use of a vehicle. Thus, the offset ranged from 2 feet to 20 feet.

 

o       Natural barriers (vegetation/standing water) - Numerous barrier walls surveyed had large swaths of vegetation planted next to them. Major types of vegetation included: Sable Palm trees, Sea Grape and various other bushes.  These vegetation lines often followed the length of the given wall ranging from 10-75 feet. Since many of the walls had some type of vegetation, an offset was incorporated into the survey. Generally all surveys were done on an average of 20 feet in front of the wall. Many of the walls not only had a vegetation line in front but also a layer of standing water. This situation occurred in areas where the walls possessed a gully or depression directly in front of the vegetation line. In many situations, the accumulated water actually formed a small linear wetland including typical wetland flora and fauna which included unfortunately high concentrations of biting insects. If these water bodies existed, the offset was increased to account for the additional obstacle so that the survey could continue. Other barriers to the survey included manmade structures such as tollbooths, embankments, bridges and narrow walks. If such obstacles were encountered, the situation was noted in the attribute table and the offset increased as needed.

 

o       GPS is a line of sight technology which relies on the ground based receiver the ability to have a clear and unobstructed line of sight to the GPS satellites. noise barrier walls provide a unique problem in that they can obstruct half of the sky depending on how close the survey is conducted to them. Due to this fact, an offset was also needed to obtain the best possible satellite lock. GPS uses a measurement called PDOP (Position Dilution of Precision) to indicate accuracy. To ensure high accuracy GPS positioning, it is recommended that the PDOP value be less than 6. During all wall surveys, PDOP was monitored very closely and any measurement greater than 6 was resurveyed.

 

ü      Limitation in the Point feature classes is where a begin or end point overlap when depicting more than one wall which are connected to each other.

 

Attribute Limitations:

 

ü      One of the limitations associated with the Noise Barrier Geodatabase was identified during the logical design. Specifically, the number of new walls that were constructed after 2000. Unfortunately, information pertaining to attributes such as WPI#, RCI#, FM#, construction dates, materials or costs were not updated to the 2000 Noise Barrier Inventory, nor was it available to be appended to the Noise Barrier Geodatabase being developed in this project.

 

ü      There were numerous yet incomplete unique identifiers associated with noise barriers such as RCI, Job number, FM number, WPI number or unique identifier assigned by an individual District office, a Key Identifier was created by CUES.

 

ü      Although the logical design of the geodatabase structure is designed to collect and store attributes significant to the noise abatement barriers, the data values for these fields are incomplete.  it is recommended that the Transportation Statistics Office, Central Office, FDOT, be the entity responsible for coordinating with other District offices in regards to acquiring the missing information within the geodatabase as well as facilitate a policy where changes or additions can be submitted to the Transportation Statistics Office from each District office so that they can update the geodatabase as part of the standard FDOT GIS base map layers and made available to all District offices.

 

 

GEODATABASE DIAGRAMMER