Complementing Harvard’s Map of the Month series, each week, Map Monday highlights a data visualization that enhances understanding of or helps resolve a critical civic issue.
Promises to rebuild America’s crumbling infrastructure have become a trope in contemporary political life. And yet, it often seems like policymakers have made little progress: in 2017, the American Society of Civil Engineers gave American infrastructure a grade of D+.
However, unequivocal statements about the poor state of American infrastructure are not particularly helpful. Rather than identifying the entire system as broken and blindly throwing money at infrastructure projects, policymakers must identify those areas in critical need of intervention. The State of Iowa has sought to do just that with its Iowa Bridge Conditions story map, a visualization of bridge conditions across the state.
Based on inspections by the Iowa Department of Transportation, the state’s GIS team plotted the condition, serviceability, and presence of any restrictions for every bridge in Iowa. While condition is an overall measure of bridge quality that takes into account a number of factors including clearances, width, and traffic levels, serviceability is a federal standard that examines bridge functionality and the presence of any structural deficiencies like inadequate length or load carrying capacity. The restrictions index identifies whether a bridge is closed or if there are any constraints on the types of cars that can cross.
The tool was originally designed for Iowa’s 2017 legislative session in order to help the Iowa Legislature understand the condition of bridges throughout the state and direct funds accordingly. The state also rolled the map out publicly so that drivers could understand the conditions of the roads they were driving on and lobby for repairs in critical areas. The map pulls data directly from the state’s production system, meaning legislators and citizens alike have access to information in near-real time and can make accurate and timely decisions.
Of the 24,140 bridges plotted on the map, about half (11,251) are in good condition, 10,818 in fair condition, and 2,071 in poor condition. 4,953 bridges are structurally deficient, 4,264 are restricted, and 429 are completely closed. This paints a picture of a state that has kept most of its bridges in working order, but must improve its maintenance practices in order to create a truly quality infrastructure system.
By collecting and visualizing timely and accurate infrastructure information, governments can start to make good on promises to revitalize American infrastructure. Often it is not a matter of building the next big and shiny thing, but rather of making practical fixes in high priority areas. Maps can point policymakers in the right direction.