US Roundabout Construction Explorere Tool

A basic interactive tool to explore US Roundabout construction over time
Author

Gabriel Zangirolani

Published

May 20, 2026

Introduction

This is a simple shiny app that allows the user to input a range of years and see the roundabouts that were constructed in the US during those years

The App

Methods

This is the dataset that was used for this app, from Tidy Tuesdays

It has been cleaned up and the coordinates have been converted to work with the USMAP function.

This is the code for the shiny app:

load("rb_cs_usmap.rda")

# filter out NA in year completed

rb <- rb_cs_usmap[!is.na(rb_cs_usmap$year_completed), ]

min(rb$year_completed)

# min is 1791

max(rb$year_completed)

# max is 2023

# let's make the plot function

rbPlot <- function(years) {
  
rb_years <- rb[rb$year_completed >= years[1] & rb$year_completed <= years[2] , ]

plot_usmap(regions = "states") +
  geom_sf(data = rb_years, aes(color = year_completed)) + 
  scale_color_continuous(low = "green", high = "red", name = "Year Completed")
  
}

ui <- fluidPage(
  titlePanel("US Roundabouts by Year Completed"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("years", label="Years", min=1791, max=2023, value=c(1900, 2000))
      
    ),
    mainPanel(
      plotOutput("yearPlot")
    )
  )
)

server <- function(input, output, session) {
  
  output$yearPlot <- renderPlot({rbPlot(input$years)})
  
}

shinyApp(ui = ui, server = server)