The city of West Des Moines is a suburban community in central Iowa of about 68,000 residents (doubling to over 150,000 during the daytime due to its location at an interstate crossroads) with 800 lane miles of pavement that are all maintained by the West Des Moines Department of Public Services.
West Des Moines Public Services has been very proactive over the years on winter maintenance operations. They have been incrementally enhancing agency practices and continuously improving performance by leveraging available resources to deploy new technologies and equipment, including:
- Road weather information systems (RWIS)
- Infrared sensors for pavement friction determination
- Automatic vehicle location (AVL)
- Mobile sensors on plows and other agency vehicles
- Integrating Mobile Observations (IMO)
- Software, including that for route optimization and a maintenance decision support system (MDSS) for material type and application determination.
These efforts have been accomplished by identifying trends and pushing technology to continuously improve and automate agency practices.
Upgrades have been made incrementally to the entire fleet of snow plow vehicles over about 10 years, beginning with the installation of AVL around 2008. This technology determines material spread rates, pavement temperature, and the plow position. As of winter 2017-2018, all 16 snow plow vehicles—which are a mix of single- and tandem-axle vehicles—are equipped with AVL, automated spread controls, and sensors.
West Des Moines contracts with a private-sector provider for weather services, such as RWIS information and MDSS outputs for strategies on how to handle storms. The MDSS outputs provide recommendations to operators on the most appropriate treatment strategy given the circumstances, including material and spreading rates. AVL and real-time data from the plow trucks are used to monitor the storm and road weather response, which includes feedback to the MDSS.
West Des Moines has also implemented plow truck route optimization. Once in place, route optimization allowed West Des Moines to more effectively meet level-of-service goals in a timely manner for arterial, collector, and residential networks.
West Des Moines believes the benefits of IMO have greatly exceeded the costs. The up-front technology costs have decreased significantly since IMO was deployed in West Des Moines. Ongoing monthly costs during the winter include about $8,700 per year for contract weather services and MDSS, and $30 per month per plow truck for AVL cellular communications and data management.
Key benefits are in the following two areas:
- Savings on materials. Reduced salt and material usage are the primary benefits of this IMO deployment. The MDSS uses real-time road weather conditions and fleet vehicle locations to provide recommendations on material type, application rates, and timing for maintenance staff to make better decisions. Specifically, West Des Moines Public Services has reduced chloride applications by 30 percent while maintaining the same level of service, saving about $150,000 annually.
- Improved agency efficiency. Route optimization has reduced the time needed to clear various areas, fuel consumption, and wear and tear on the plow truck fleet, resulting in about $50,000 savings per year and the ability to do more with less. With increased data available for review after a winter weather event, agency staff can examine the storm progression using available road weather data such as friction data and RWIS photos and then compare it to the operational strategy and results. This is used to modify and enhance the operational strategy including truck placement, material type, and application timing of materials to better meet level of service goals for future winter weather events.