Socioeconomic Data Updates

Utah County Household & Population Adjustments

Version 9.1.1 includes a secondary (revised) household and population forecast reflecting new housing developments in the Utah County (MAG) region from 2019 to 2025. These forecasts are based on the 2023 5-year estimates from the American Community Survey (ACS). This revised forecast incorporates observed growth between 2019 and 2025 and is then aligned as closely as possible with the existing 2050 forecast. The employment forecast remains unchanged. The new socioeconomic (SE) files can be found in the 1_Inputs\2_SEData\3_MAG directory, within the Adjusted_to_NewGrowth folder.

These forecasts have not been formally adopted as an amendment to the 2023–2050 RTP and therefore are not the default socioeconomic inputs to the model. However, this secondary dataset is available and may be used at the modeler’s discretion.

Household & Population Adjustments Across Districts

Figure 1 and Figure 2 show household and household population forecasted adjustments at the district level. Across the region, household projections for 2050 show slight changes: The large districts of Central Utah Valley and South Utah Valley see a modest decline in households, while the Cedar Valley and Goshen Valley districts remain relatively consistent. In contrast, North Utah Valley shows an increase in projected households.

Figure 1: Revised Household Forecasts (City Groups))

Figure 2: Revised Household Population Forecasts (City Groups)

Household & Population Adjustments Across Cities

Figure 3 shows household, household population, and household size forecast revisions at the city level. Similar patterns that exist at the district geography exist at the city level geography. For example, Provo and Orem show a lower level of household population (like with Utah Valley Central) and Lehi and Draper show an higher level of household population (like with Utah Valley North). However, the patterns may not be entirely consistent across all cities.

Code

dataLT = transpose(df)

validCities = Array.from(new Set(dataLT.map(d => d.CITY_NAME))).sort()

viewof citySelect = Inputs.select(
  validCities,
  { label: "City Name" }
)

viewof seSelect  = Inputs.select(new Map([['Total Households','TOTHH'], ['Household Population', 'HHPOP'], ['Household Size', 'HHSIZE']]), {value: 'SE_VAR', label: "SE Variable"});

Code

dfData = dataLT
  .filter(dataL =>
    citySelect == dataL.CITY_NAME &&
    seSelect == dataL.SE_VAR &&
    dataL.Year > 2018
  )
  .map(d => ({
    ...d,
    Source: d.Source === "v910" ? "Adopted" :
            d.Source === "v911" ? "Revised" :
            d.Source
  }));

yMax = Math.max(...dfData.map(d => d.SE_VAL))
seLabelMap = new Map([
  ['TOTHH', 'Total Households'],
  ['HHPOP', 'Household Population'],
  ['HHSIZE', 'Household Size']
])
yLabel = `${citySelect} ${seLabelMap.get(seSelect)}`

Code

Plot.plot({
  grid: true,
  aspectRatio: 0.5,
  x: {label: 'Year', tickFormat: d => d},
  y: {
    label: yLabel,
    domain: [0, yMax], 
    fontSize: 18
  },
  marginRight:140,
  marginLeft: 140,
  color: {legend: true},
  style: {
    fontSize: 12
  },
  marginTop: 60,
  marginBottom: 60,
  height: 500,
  width: 800,
  marks: [
    Plot.line(
      dfData, {x: 'Year', y: 'SE_VAL', stroke: 'Source', strokeWidth: 3})
  ]
})

Figure 3: Revised Household, Household Population, and Household Size Forecasts (City)

Effect of Household & Population Adjustments on Roadway Volumes

Figure 4 through Figure 7 compares the roadway volumes between the revised and the adopted socioeconomic data. These figures show how the revised socioeconomic data affects the roadway volumes with blue segments showing a decrease in traffic and red showing an increase. In 2023, an increase in volumes along I-15 exists along North Utah County into South Salt Lake County. A similar pattern of higher volumes exist along other major roadways in North Utah County and South & Central Salt Lake County from 2032 to 2050. Alternatively, a decrease in roadway volumes seem to occur along Central to South Utah County from 2032 to 2050. These shifts in volumes are relatively consistent with where population estimates were revised – higher volumes along corridors with higher population and vice versa.

Figure 4: Segment-Level Revised vs Adopted Comparison - 2023

Figure 5: Segment-Level Revised vs Adopted Comparison - 2032

Figure 6: Segment-Level Revised vs Adopted Comparison - 2042

Figure 7: Segment-Level Revised vs Adopted Comparison - 2050