Project Objectives and Impacts

What planning objectives is the project intended to achieve? What impacts should be considered in economic analysis?

Transportation planning tends to have multiple objectives, which usually include:

    • Traffic congestion reductions

    • Parking cost savings

    • Consumer savings and affordability (savings to lower-income households)

    • Improved mobility for non-drivers

    • Improved safety

    • Energy conservation

    • Air, noise and water pollution reductions

    • Habitat protection

    • Support for local economic development

    • Improved public fitness and health (from increased walking and cycling)

Although a project may have one primary objective, such as reducing congestion or improving mobility for non-drivers, transportation agencies should generally try to maximize social benefits by selecting projects that help achieve multiple planning objectives. For example, when evaluating various congestion reduction options it is desirable to select those that also help reduce parking costs, improve mobility for non-drivers, and increase safety. Conversely, when evaluating transportation energy conservation strategies it is best to choose those that also reduce traffic and parking congestion.

As much as possible, all significant impacts (benefits and costs) should be considered in economic analysis. Many impacts can be quantified and monetized (measured in monetary values), using methods described in this website, and so can be incorporated into benefit-cost analysis. Others may be unsuited for monetization, but should still be described and quantified as much as possible (for example, by estimating the acres of wildlife habitat that will be impacted, or the number of non-drivers who will benefit from improved mobility options) so they can be effectively considered in the planning process.


Project: Straightening a curve in a road

Purpose: To reduce accidents

Unintended effects: Reduced travel time

Benefits: Reduced accidents and travel time

Project: New bus route

Purpose: To provide mobility for transit-dependent people

Unintended effects: Reduced automobile trips, bus noise on new route, people waiting at new bus stops

Benefits: Increased person-trips, reduced automobile congestion and noise, noise from buses (a negative benefit), effects on property adjacent to bus stops (these effects may or may not be significant and may be negative or positive -- people trampling a lawn and dropping trash or people patronizing an adjacent neighborhood store)

Project: Changeable message signs on a congested freeway providing travel time via an alternate route

Purposes: To reduce overall delay by encouraging alternate routes, to reduce travel time uncertainty

Unintended effects: Increased delay on alternate routes and connecting streets

Benefits: Reduced overall travel time on freeway, increased overall travel time on alternate routes and connecting streets (negative benefits).

Intended Recipients

These will depend on the perspective of the sponsoring agency. A city may wish to consider only the benefits and costs that accrue to city residents. A federal agency, allocating funds for new transit starts, is likely to consider the costs and benefits to all involved. A large state, such as California, with significant manufacturing and trade, may consider benefits and costs to all parties in prioritizing highway projects, while a small state, with substantial through traffic that does not substantially benefit its economy, may desire to focus only on the costs and benefits to the state's residents and businesses. This tendency to take a parochial view is a potential pitfall in that, when applied properly, benefit-cost analysis should be broad enough to consider all persons who incur significicant costs or benefits.

Unintended Effects

The term "unintended effects" is used to focus attention on a project's foreseeable side effects that may be either good or bad. These are important in evaluating and gaining support for projects. For example, a project that is effective in reducing automobile congestion may make pedestrian or bicycle travel more dangerous, while an alternative that is somewhat less effective in reducing automobile congestion may not reduce pedestrian safety and may thus have greater overall benefits. In the bus route example above, awareness that bus stops affect adjacent property may result in locating stops so as to minimize damage.


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