Overview
While the Transportation Project Impact Case Studies (T-PICS) screening tool developed in SHRP 2 Project C03 portrays the general range of economic impacts associated with various transportation projects, most agencies also move on to examine the specific changes in transportation conditions associated with individual project proposals as well as their economic consequences. SHRP 2 Project C11 provides spreadsheet tools to assist local agencies in moving on to this next stage.
The foundation for this project is the fact that transportation projects can lead directly to wider benefits that stem from more than just the traditional measures of traveler impact, which are based on average travel time and travel cost. These wider benefits are effects on business productivity, factors that enable businesses to gain efficiency by reorganizing their operations or changing the mix of inputs used to generate products and services. There are at least three classes of transportation system impacts that can directly lead to wider benefits for business organization and operation: travel time reliability, intermodal connectivity, and market access. These three classes of effects are the focus of this report and are summarized as follows.
Reliability
Some transportation projects are designed to reduce congestion. Those projects may reduce not only average travel times, but also the likelihood of traffic incidents and length of traffic backups that result from each incident. That brings less variability and uncertainty in freight pickup and drop-off times and hence fewer late deliveries. The reduction in late deliveries can enable reduction in inventories and more centralized warehousing and delivery processes to be put in place. These effects are often referred to as supply chain logistics benefits. It is also possible for reliability improvement to reduce employee lateness and hence enable business operations to make more productive use of workers because they show up on time. This effect is often referred to as a labor productivity benefit.
A reliability assessment spreadsheet was developed for this study (Chapter 3). It takes information on the type of highway, projected traffic volume, speed, lanes and capacity, and it then generates measures of a travel time index, average delay, buffer time, and cost of delay. The travel time index and buffer time provide a basis to further calculate the direct economic value of improving reliability, in a separate accounting spreadsheet (the accounting spreadsheets for reliability as well as those for market access and intermodal connectivity are described in Chapter 2).
Intermodal Connectivity
Some transportation projects have the effect of enhancing the frequency of service and reducing total time involved for bus, car, and/or truck movements from business locations to intermodal terminals (including airports, marine ports, rail terminals, and intermodal truck and rail facilities) and vice versa. Other transportation projects may enhance the frequency of air, marine, and/or rail services or enhance the breadth of origins and destinations directly accessible from those terminals. Either way, the result is a faster movement for intermodal travel between some origins and destinations. That can be viewed as reducing travel cost for existing movements, as well as enabling new movements between origins and destinations that were previously not practical or economically feasible.
An intermodal connectivity assessment spreadsheet was developed for this study (Chapter 4). It takes information on the specific intermodal port or terminal affected by a transportation project, projected ground access volume, change in access time, and fraction of vehicles on the affected access routes that have that terminal as their destination. It then looks up information regarding the modes and destinations served by that facility, and from that data it generates a connectivity index. This index provides a basis for calculation of the direct economic value of improving connectivity, in a separate accounting spreadsheet.
Market Access
Some transportation projects have the effect of expanding the breadth of destinations that can be served by same-day truck deliveries from a given business location, or the breadth of area from which a business can reasonably expect to draw customers and workers. These effects are often represented as changes in the effective size or the effective density of the customer market and labor market available to the firm. Expansion of the customer delivery market can enable scale economies in production and delivery processes. Similarly, expansion of the worker labor market can enable scale economies through better matching of specialized business needs and specialized worker skills, and it can also enable more innovation through greater interaction of complementary firms and their employees.
Two market access assessment spreadsheets were developed for this study. One tool uses an effective density metric with a spatial decay factor to assess access from a firm to buyers and suppliers. This tool can also be used to assess labor market access. The second tool uses an impedance threshold metric to assess commuter access. Both work on the same general principal. They take information on zonal population or employment as well as distance or time decay factors and then generate measures of effective market size or effective market density. This information can be used to calculate the direct economic value of improving accessibility, in a separate accounting spreadsheet.
The results from all three categories of project impact spreadsheet can be used directly to generate project impact indicators useful for project evaluation and prioritization processes such as multi-criteria rating systems. They can also be used as drivers for benefit–cost and economic impact models. To aid in this process, a generalized benefit–cost accounting framework is also presented as a fourth class of spreadsheet tool. The accounting framework shows how results of the travel time reliability, intermodal connectivity, and market access tools can be used, together with traditionally measured travel time and travel expense measures, to more fully assess the direct economic benefits that a given roadway improvement may have on both travelers that use it and the operation of businesses that depend on it (for workers, customers, and deliveries). These results can also be used to drive more sophisticated economic impact forecasting and analysis systems to more fully estimate the long-term regional economic growth implications of proposed projects.
Related Artifacts: C11 Reliability User’s Guide; Project C11 – Reliability Module