McHenry County implements GIS technology to enhance snowplow application
Nicole Gattuso, GIS Manager, McHenry County, IL
R. Mark DeVries, Superintendent of Operations, McHenry County Division of Transportation, Woodstock, IL, and member, APWA Winter Maintenance Subcommittee
Xun Zhang, GIS Technical Manager/Lead Developer, Bruce Harris and Associates, Batavia, IL
Mike van Meeteren, Systems Engineer, Cirus Controls, Brooklyn Park, MN
McHenry County is one of the fastest growing counties in the State of Illinois. During winter months, it is imperative for the McHenry County Division of Transportation to effectively route snowplows to enhance operational efficiency. McHenry County developed a GIS website to manage the snowplow fleet and to analyze the application of salt along routes in an effort to maximize the use of limited resources. This article covers the implementation of Wireless, GPS, laser and other latest technologies for data collection, n-tier distributed system architecture powered by ArcIMS and ArcSDE software, benefits achieved, and lessons learned from our experience.
The McHenry County Division of Transportation (MCDOT) has been proactive by necessity in its winter maintenance operations. Located in northeastern Illinois along the Wisconsin border, the County gets its share of severe winter weather. MCDOT maintains 230 centerline miles of roadway and approximately 550 lane miles of road. MCDOT cannot support 24-hour coverage with its limited staff, so running an efficient operation is vital.
The County road system is divided up into 19 snowplow routes averaging 28 miles per truck. MCDOT incorporates additional staff and equipment during large events and at times splits its crew to provide 24-hour coverage but a lower level of service.
MCDOT snow and ice removal systems have evolved in recent years to incorporate the most modern methods and best practices. In 2000, MCDOT added computer-controlled dispensing systems. In 2004, MCDOT developed a passive snowplow tracking system. In 2005, MCDOT incorporated the snowplow tracking system into the County-wide GIS. Now, MCDOT not only tracks their vehicles and thematically maps operational statistics at their offices but also provides data throughout the County and to the public.
Building the snowplow tracking system
Beginning in the year 2000, MCDOT changed its fleet vehicles completely incorporating new upgrades: automatic transmissions, patrol wings, pre-wetting systems, tarps, modern hydraulic systems and computer-controlled granular and liquid dispensing systems. In 2004, the decision was made to track operations with passive data, and a wireless data download was created.
Computer-controlled dispensing systems. The computer-controlled granular and liquid dispensing systems allowed the operator to dispense materials at precise increments at all speeds. While the units precisely dispense materials, they record operational statistics such as speed of the vehicle, distance traveled, amount of material dispensed, amount of liquid dispensed, pavement temperature, ambient temperature and several other functions. These early units were not capable of gathering GPS information and MCDOT wanted the ability to track where the plows had been and display the data on a map.
The tracking system: live vs. passive data. MCDOT's Superintendent of Operations attended many different seminars and gathered information from vendors regarding various GPS tracking systems. Most were active web-based systems where the County purchased the hardware, the vendor held the data and the County would be given access. The County had to reassess its position and evaluate why it needed the data live.
It was determined that the data did not need to be live for the following reasons:
Subsequently, the search for a passive system began. Research showed that most passive systems gathered data and then the organization must physically remove the data from the unit in the truck. This was accomplished using a laptop and a data cable. This was certainly an option but it was time consuming as well.
Going wireless with the development of the Drive by Download system. MCDOT worked with a vendor to develop a system that would download the data using a wireless connection as the vehicles entered the maintenance shed. The result was the Drive by Download system.
The Drive by Download system consists of several components that allow the wireless transfer of data from one or many trucks to a central computer. Formatted data can be used to determine how much material (salt, brine, etc.) was used in snow removal and ice prevention, where the vehicles were located, what time, speed vehicle was traveling, and equipment fault codes, etc. The Drive by Download system can be broken down into the following components:
The Drive by Download system uses a Garmin GPS17HVS antenna to receive positional data. A Sprague RoadWatch sensor is also needed to collect ambient and road surface temperature.
Another component is the spreader control system called the SpreadSmart spreader. The SpreadSmart spreader controller receives data from sensors, records this information in non-volatile memory, and transmits this data when the vehicle is in range of the base station.
The third component is the wireless ethernet bridge. The system uses standard 802.11 networking technologies to transmit its data to the base station. Using a standard transmission technology ensures availability and compatibility with Windows compatible computer equipment.
The fourth component that is needed is the wireless access point. The access point is the physical receiver for the data. It is connected to a base station computer which is responsible for managing the wireless connections.
A fifth component is the Drive by Download software. This software runs on a standard Windows platform as a server application. The software checks at a setable interval whether vehicles are in range of the wireless system. If a vehicle is detected, the data transfer process is started, and the data is extracted from the spreader controller. Once finished, the data is stored to the hard drive of the computer (or optionally somewhere on the LAN of the installed site) in an ASCII comma delimited file.
The sixth component of the Drive by Download system is the Shapemaker software. The Shapemaker software is what converts the ASCII comma delimited files into a shapefile. This data can then easily be imported into GIS software such as ArcView, where it can be further manipulated into maps, reports, and other GIS functions.
Recognizing the need to refresh skills between winters, a user's guide was created by GIS staff to assist MCDOT staff in viewing shapefiles.
Incorporating snowplow tracking system into the County-wide Enterprise GIS
Once the data was channeled to a computer in the maintenance section, the data needed to be displayed on a map. MCDOT coordinated with McHenry County's GIS Manager to take the system to the next level. MCDOT wanted a fast and user-friendly way of displaying data needed on a map without having to have a great deal of knowledge of any GIS software. MCDOT worked with the GIS Manager to create an application that would meet the needs of displaying the data on a map in a user-friendly environment.
The GIS Manager worked with a GIS developer (Bruce Harris and Associates), the Superintendent of Operations and the vendor (Cirus Controls) who created the Drive by Download system to develop the application as part of the County-wide enterprise GIS and achieve the goals years before expectations.
System architecture. The snowplow tracking system was incorporated into the County-wide enterprise GIS which is powered by ESRI ArcIMS, ArcSDE and ArcEngine Technology. The hardware includes a web server, an ArcIMS application server and ArcSDE Database Server.
The snowplow tracking system as part of the County-wide GIS has three components:
Component 1: Snow Plow Uploader. The McHenry County GIS Manager decided it would be best to have a web-based interface that was easy to use and to have the information on the website update automatically. Using a web-based interface would allow multiple people within MCDOT to view the data without having to have additional GIS software installed on individual computers. The GIS Manager worked with a consultant to develop an interface that would automatically convert the shapefiles to a geodatabase within ArcSDE. This interface is called the Snow Plow Uploader.
The GIS Manager wanted MCDOT to have the ability to upload the information without having to go into ArcCatalog. This would allow users to upload information without having much knowledge of GIS. The advantages of storing the data within the geodatabase environment are the following:
The Snow Plow Uploader will upload all the point data into an ArcSDE snowplow points feature class. After the upload is completed, the points are converted into lines and the snowplow lines feature class is created, with line angle as an attribute. When converting the points into lines, it allows the viewer to see the data as one continuous flow. At the same time an offset of the snowplow lines feature class is created and inserted into a feature class called snowplow offsetlines. The offset is created with an algorithm described below. Creating an offset of the line feature class allows the viewer to see the direction of the snowplow. This has been developed using ESRI ArcEngine Technology.
Snow Plow Route Uploader Offset Algorithm. The Snow Plow Uploader organizes GPS point data into route groups based on truck, date, and time. Consecutive points are converted to line segments and appropriate starting and ending attributes are carried to the line feature records. An additional offset polyline feature class is populated to better visually represent trucks traveling on the same road in different directions.
The offset algorithm is an extension of the polyline construction process. It requires existing line features. Every line segment is assumed to be between two other segments so a perpendicular mean angle can be established. If the line feature isn't between two other features, i.e., it's the first or last in a route, then the perpendicular angle is used. Since every two sequential line segments have two angles between them (an acute and an obtuse) the angle on the right-hand side of the line flow is used. The specified offset distance (20 feet) refers to perpendicular distances, so a hypotenuse distance must be calculated along the perpendicular mean angle to locate a new endpoint for the line segment.
There are two special cases where this logic is not followed:
Component 2: Developing the Intranet Administrative Application. After the data is uploaded to ArcSDE through the uploader it is automatically pulled by an ArcIMS website. An intranet application allows users within the County, with appropriate permissions, to access the snowplow trucks information.
Component 3: Internet Application for Public. McHenry County is currently testing a website that will be deployed on the Internet for public use. This will allow the public to view the location of the snowplows within the last three hours of the day. The public website prototype allows the user to zoom in and out in a simple viewer. This is a user-friendly interface and does not require any additional software to be downloaded to view. Providing the location of the snowplow trucks within the last three hours, allows the public to make more informed decisions before traveling in a winter storm.
Benefits and future uses
The benefit of the visual and statistical data that is compiled allows the MCDOT staff to make informed decisions. The visual map display allows the viewer to track where the snowplow has been, the pavement temperature, speed, the amount of salt applied, etc. Having an understanding of the pavement temperature allows the staff to adjust the application of salt to the road conditions. Not only can a visual reference be seen, but a statistical calculation can be created as well. This allows better efficiency in the application of salt brine and in the end will save in cost.
MCDOT continues to improve operations with technology. In addition to providing maps of the routes traveled by the snowplows, the operational statistics collected by the computer-controlled dispensers are able to be displayed on maps to evaluate operations beyond time and location variables.
In the future, it is hoped that regular evaluation of snowplow operations using this data will continue to provide a tool to use resources more efficiently, assist in management of operations, and increase safety with having a better understanding of the roadways.
Nicole Gattuso can be reached at (815) 334-4280 or firstname.lastname@example.org; R. Mark DeVries can be reached at (815) 334-4975 or email@example.com; Xun Zhang can be reached at (630) 761-0951 or firstname.lastname@example.org; and Mike van Meeteren can be reached at (763) 493-9380 or email@example.com.