Baseline 2020: Transportation

Source and Assumptions

Transportation planning in the Greater Wasatch Area is the responsibility of the Utah Department of Transportation, Mountainland Association of Government, Wasatch Front Regional Council, Utah Transit Authority, and local governments. The projections prepared by these entities inform decisions regarding transportation infrastructure investments. Transportation projections are also critical to the monitoring of air quality. The fundamental logic of the modeling process used in the metropolitan counties follows the general points listed below. These points are followed by the main assumptions.


  • Projections of vehicle miles traveled (VMT) are based on analysis of trip generation, trip distribution, mode choice, and route choice.
  • Trip generation between and among small areas is based largely on the residential and employment characteristics of these areas. For instance the more employment an area has, the more work trips it generates. The more retail employees located in an area, the more shopping trips that are attracted.
  • Trip distribution is allocated based on the premise that the more distant the destination, the more costly the trip.
  • The mode choice includes the option to take public transit, drive alone, car pool, or travel in a non-motorized mode such as walking or bicycle. Choices are based on the attractiveness of each mode as measured by accessibility to mass transit, automobile ownership, costs and time required to use the mode, and pedestrian friendliness.
  • The choice of route is determined by the best path through the highway network for each type of trip based on the shortest route in terms of time and distance.

  • The projections are based on detailed observations about the number of individual trips made by different sized households and the number of vehicles they own. For instance, in Utah County trips per day per household range from 4.7 for a one person household to 32.7 for a six or larger person household.
  • The projections also include projections and observations about the demand for the travel of people and goods. Commuting and work related travel comprise 30 percent of the travel.
  • Initially, drive-alone-travel comprises 77 percent of total trips, followed by 14 percent with one passenger, 3 percent by bus, and 7 percent walking, bicycle, working at home, or other. These percentages change as population grows and the transportation system develops.
  • Cost estimates for major transportation infrastructure developments include those projects that are part of the long range plans of the Metropolitan Planning Organizations, Utah Department of Transportation, and Utah Transit Authority. These include local municipality investments when they are part of the regional plans, but exclude them when they are not. Transportation cost estimates are therefore minimum estimates and some estimates are higher.
  • The major projects included in the cost estimates are I-15 reconstruction in Salt Lake, Davis, and Utah County, sections of the Legacy Highway in Davis, Salt Lake County, and Utah Counties, I-80 improvements, Bangerter Highway extensions, Highland Drive extensions, and the North-South TRAX light rail line. Dozens of smaller projects have been identified and included. Commuter rail and East-West and South Valley light rail extensions are excluded.


Characteristics and Trends

Average weekday vehicle miles of travel are projected to increase from 40.7 million in 1995 to 76.9 million in 2020. The annual growth in VMT during the next 25 years of 2.6 percent is higher than the projected annual growth in population of 2.1 percent. VMT per capita is projected to increase from 25.1 in 1995 to 28.5 in 2020.

Current investment will increase speeds by 5 percent in the early years. Average peak period speeds over the entire period, however, are projected to decline from 29 miles per hour in the metro counties in 1995 to 23 miles per hour in 2020. Peak period delay per trip is projected to more than double in the metro counties from 4.4 minutes in 1995 to 9.7 minutes in 2020. Average peak period delay in terms of vehicle-hours increases from 70 thousand in 1995 to 250 thousand in 2020. These reductions in the transportation system's performance occur despite the major investments in highways and mass transit included in the baseline.

Mass transit ridership is projected to increase from 23.5 million in 1995 to 39.1 million in 2020. This level of ridership is based on the provision of comparable levels of bus service and only the North-South TRAX light rail.

Major Issues and Findings

The anticipated growth in VMT and mass transit ridership in the Greater Wasatch Area introduces several major issues and findings that are relevant to the understanding of the baseline and the development of alternative scenarios. These include the following:

  • The use of roads in the Greater Wasatch Area as measured by total vehicle miles of travel is projected to increase at a rate faster than population growth. This occurs as residents continue to increase vehicle ownership, drive farther for work trips, and make more non-work trips. A changing age structure and increasing female participation in the labor force also impact this trend.
  • Demand for transportation will continue to exceed the state's ability to build new facilities. Even with the aggressive highway and mass transit development plans which will succeed in the early years to increase average speeds and reduce congestion, the average commute in 1995 of 24 minutes is projected to increase to 34 in 2020. Over the entire period average peak period speed is projected to decline from 29 mph in 1995 to 23 mph in 2020. Minutes of peak period delay per trip is projected to increase from 4.4 in 1995 to 9.7 in 2020.
  • The performance of the transportation system would be far worse in the future without the current levels of investment. For instance, without the additional capacity investment of the transportation plans in the Salt Lake-Ogden Urbanized Area, average speeds in 2020 would be 12 miles per hour.
  • Future maintenance and repair costs will take up a larger portion of future budgets than they have in the past. Existing transportation infrastructure is aging and increased traffic will quicken that deterioration.
  • The investment in light rail will provide some mobility benefits throughout the region and will help increase accessibility, air quality, congestion reduction, and cost effectiveness. However, much of the current and projected mass transit system is based on buses which operate in the same congestion as the automobile.
  • Current transit revenues will not support expansion beyond the already planned development of the North-South TRAX and bus service comparable to what exists today.
  • Transportation infrastructure development is projected to exceed $9.7 billion between 1995 and 2020 (current 1997 dollars). This equates to $3,600 per person and $10,100 per household in the year 2020 . There are those who believe that the total need is even greater.(7)




7. Infrastructure costs were estimated based on the plans of the agencies providing transportation and water services. With each of these types of services, a list of projects was developed based on the agencies' plans. The project list was then tabulated and an estimated total cost for each type of infrastructure was developed. The estimated costs are for the 25 year period from 1995 to 2020 and are in 1997 inflation adjusted dollars. If all the identified projects are actually built, and are built as currently anticipated, the actual amount of money spent will be greater than the total reported here because of inflation between now and 2020. Per capita and per household costs are based on the estimated population and households in 2020.

In the case of transportation, the $9.7 billion total is based on the long range plans of Utah Department of Transportation, Wasatch Front Regional Council, and Mountainlands Association of Governments. Hundreds of projects are identified in these plans. The projects range in size from $100,000 minor surface work to the $1.59 billion I-15 reconstruction in Salt Lake County. 



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