A Sampling of Emissions Analysis Techniques for Transportation Control Measures

Introduction

Forecasting Approaches

Selecting a Method

Key Inputs and Outputs for Each Method

References

List of Acronyms

Overview - Quick-HOV is a set of procedures and a software model for predicting and evaluating the impacts of HOV lanes on person travel, vehicle travel, auto occupancy, congestion, delay, air quality, and fuel consumption.

Strategies Addressed - HOV lanes; traffic flow improvements (ramp meter bypass).

Methodology - The methodology addresses HOV facilities proposed for specific links in the transportation network. Travel time differences are computed based on facility and demand characteristics, and are used to predict demand shifts. An equilibration process balances supply and demand. Emissions are calculated using MOBILE5 or EMFAC emission factors, based on the speeds and mixes of traffic.

Data Requirements - Project description inputs include various characteristics of the proposed HOV facility and parallel roadway, such as length and capacity. Demand and travel inputs include peak-period and free-flow travel times, vehicle volumes, and person volumes. Parameters are assigned default values that can be changed by the user.

Outputs - Changes in person travel, vehicle travel, auto occupancy, congestion, delay, air quality, and fuel consumption.

Level of Effort - Quick-HOV is a Windows-based application that is easy to use. The calculation methodologies are generally straightforward and easy to apply. The calculation steps are clearly documented. Some effort may be required to develop assumptions appropriate for local use.

Advantages - The Quick-HOV model can provide a reasonable estimate of HOV facility diversion and use, along with corresponding emissions benefits, without the data and time requirements for a network-level analysis. At the same time, the methodology includes enough facility-specific detail that it should be more accurate than the sketch-planning approaches embodied in more general TCM analysis tools.

Limitations - Some effort is involved in developing the inputs for the model and running the model. It does not account for network-level changes in travel patterns or traffic flow characteristics.

Source/Availability - The Quick-HOV model, developed for FHWA in 1996, is a DOS-based software program. It is distributed by McTrans (352-392-0378, mctrans@ce.ufl.edu) at a cost of $250. The documentation only is available for $20.

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