ITS Architecture Implementation Program
time lapse of traffic traveling down and exiting from a freeway at night
21st Century Operations Using twenty-first Century Technologies

Executive Summary

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The Nashville Regional Intelligent Transportation Systems (ITS) Architecture was prepared to guide the implementation of ITS systems in the Nashville region, with a goal of improved system-wide traffic and incident management. The Nashville region is defined to include Cheatham, Davidson, Robertson, Rutherford, Sumner, Williamson and Wilson Counties. The time frame considered in the Plan is a 20-year horizon.

The Plan was developed through a consensus process that involved a variety of ITS stakeholders in the study area. This included representatives from the Tennessee Department of Transportation (TDOT), the Nashville Area Metropolitan Planning Organization (MPO), local traffic management agencies, emergency service providers, transit system operators, the Federal Highway Administration (FHWA), local planning agencies and other transportation stakeholders.

In conducting this effort, a systematic approach was taken that utilized nationally available information on ITS deployment along with the results of several recent ITS related studies that have taken place in the Nashville region. This included the Nashville Area ITS Early Deployment Plan and the Nashville Regional Incident Management Plan.

As an initial step, traffic performance measures were generated and user service needs were defined, leading to the selection of ITS deployment locations and market packages that would meet the priority traffic and incident management needs of the Nashville region.

Over the 20-year planning horizon, the following ITS elements are recommended for implementation in the Nashville region:

  • Freeway surveillance, covering 320 centerline miles
  • Surface street control and surveillance, covering 296 centerline miles
  • Freeway service patrols, covering 320 centerline miles
  • Construction of a regional transportation management center and nine traffic operations centers
  • Use of electronic fare boxes and automated tracking on transit vehicles
  • Operation of two transit management centers
  • Installation of 19 transit traveler information sites
  • Communications to support the private broadcast of interactive traveler information
  • Communications to support regional traffic control
  • Communications to improve railroad highway grade crossing safety
  • Installation of ten roadside weather stations
  • Communications to support emergency response/routing
  • Traffic signal preemption on selected surface streets
  • Implementation of a virtual data warehouse for traffic/safety information storage and transfer
  • Support for traffic forecasting and demand management
  • Parking facilities management in downtown Nashville
  • Reversible lane management on selected surface streets

As with any major transportation initiative, ITS deployment should be implemented incrementally, both to maximize system effectiveness and to recognize limitations on available funding. With this in mind, the recommended implementation schedule was divided into three phases: 0-5 years, 5-10 years and 10-20 years. Projects were assigned to each phase based on a desire to address the most critical traffic and safety needs first.

For each phase, estimates of capital, operations and maintenance (O&M), and capital replacement costs were developed, as shown below:

ITS Funding Requirements (millions of 1999 dollars) [1]
empty cell Capital O&M Capital Replacement Total
0 to 5-Year Increment $42.49
 $14.65 $ 0.00
 $57.14
5 to 10-Year Increment $30.22 $29.20 $ 0.00 $59.42
10 to 20 Year-Increment $58.91
 $69.18 $36.96 $165.05
20-Year Plan $131.62 $113.03 $36.96 $281.61

[1] The discount rate used was 7.00%

These cost estimates are inclusive of funding requirements for the entire integrated system, recognizing that different stakeholders will be bearing the cost of different ITS components. Moreover, it includes consideration of existing and programmed ITS projects.

The approach recommended for the Nashville region assumes decentralized management and operation of ITS components that are integrated into an overall regional system. As a result, providing a ITS system that appears seamless to the traveling public becomes an important institutional challenge. To successfully implement ITS within the region, agreements must be reached between involved parties to ensure that respective roles and responsibilities are clearly understood and that a full commitment of all involved has been made.

This is considered a living document that should be updated on a regular basis to reflect changes in travel patterns, gains in local ITS knowledge and experience, advances in ITS technology, access to improved cost estimates and changes affecting funding availability. The preferred update schedule is every three years, to be consistent with the Long Range Transportation Plan updating process.