Quantification of Latent Travel Demand on New Urban Facilities in the State of Texas

I recent years there has been a growing concern over the congested conditions of our urban highway facilities. The continuing escalation of adverse driving conditions in major urban areas has generated a feeling of discontent among automobile owners and transportation planners alike. One major factor that has contributed to this feeling of dissatisfaction is the rapid pace with which many of the new highway facilities are being filled to capacity. In some instances, the traffic volume on a new facility will grow at such a rapid pace that within only a few years the twenty-year design volume will be exceeded. While the financial constraints of local, state, and federal governments may never permit the construction of highways that provide sufficient vehicular capacity for long-term traffic demands, there should at least be the capability to accurately predict near-term future traffic volumes on new highway facilities. A significant factor affecting future traffic volumes on new highway facilities is that of latent travel demand. Latent travel demand is defined as additional traffic that desires to use an existing facility, but is discouraged from doing so by the unsatisfactory operation of the facility caused by high levels of congestion. ] Latent travel demand is commonly divided into the components of converted traffic (switch of modes), diverted traffic (switched routes), and induced traffic (new trips), and it constitutes the majority of the initial vehicular traffic that will use a new highway facility.’ Because the traditional transportation planning process does not consider latent travel demand, when new facilities are constructed that provide a significant reduction in travel time within an area, the resulting traffic volumes are often seriously underestimated. This can be attributed to the fact that existing forecasting techniques have yet to quantify the component of future traffic volumes designated as latent travel demand.