Construction Impacts

What is the traffic impact during construction? How will the construction be phased to minimize traffic impacts during construction? Interruptions to traffic could be expected during off-peak hours. Construction would be phased in a manner that prioritizes those areas of the Corridor that have the greatest need or add more immediate utility to the transportation system. Disruption to traffic by temporary lane closures or reducing the normal number of through lanes would be avoided during peak travel times. Construction of any alternative would be phased in such a manner that the operation of the existing highway would be maintained throughout construction.

Localized Congestion

Why was the “pinch point” plan (only solve congestion problems at bottleneck locations) not one of your studied alternatives? Studies show that alternatives limited to local pinch points would not accommodate the travel demands projected for the Corridor and, therefore, have not been included among the alternatives retained in the PEIS. Person trips are projected to increase by more than 10 million trips (an increase of 65 percent) at the Eisenhower-Johnson Memorial Tunnels over the next 25 years. Ninety-six percent of the westbound traffic is bound for areas west of Idaho Springs. Seventy-four percent of westbound traffic is bound for destinations west of the US 40/Empire exit.

Travel Time

What is the benefit of the travel time savings of the alternatives? Due to the increases in projected demand, travel time will not change appreciably from today’s travel time. In some instances, the hours of congestion will reduce from double digits to single digits. If no major improvements were made (that means the capacity remains the same as the current condition) along the Corridor, to accommodate this huge growth, the travel time between Glenwood Springs to C-470 for a distance of 144 miles would be approximately 460 minutes (over 7 hours) with a trip to Vail taking nearly 4 hours.

Purpose and Need Assumptions

Why increase the capacity for only weekend congestion? Projections indicate that by 2025 weekday traffic on the eastern part of the Corridor will begin to mimic year 2000 weekend traffic.

Could congestion eventually be reduced by not increasing capacity and taking No Action? Is increased capacity really necessary? Suppression of trips for the No Action alternative would result in reduced demand (from the 2025 Baseline prediction), congestion during peak travel would continue with greater hours of congestion, and suppression of the Corridor economy would also result.

Travel Demand Model

How reliable is your travel demand model? The I-70 travel demand model develops credible estimates of travel forecasts both for the purpose and need and for evaluating transportation alternatives in this study. It is important to understand that travel forecasts in the I-70 Mountain Corridor necessarily focus on recreational travel. The demand models developed for this PEIS, therefore, represent leading-edge research into this increasingly important aspect of travel behavior.

The analysis combines conventional four-step travel demand models with a traffic simulation model to address the effects of queue formation at bottlenecks, and differences in vehicle characteristics on average highway speeds and effective capacity. This approach goes significantly beyond most conventional travel forecasting procedures used to evaluate alternatives.

Classifying the segments of the I-70 Corridor based on transportation system characteristics and travel demand characteristics are particularly helpful in addressing the diversity of transportation issues that must be considered for each alternative. Furthermore, the detailed stratification of Corridor travel demand by trip purpose provides a well-structured basis for forecasting future total demand under each alternative.

Transit Ridership

How many people will ride the transit? Transit systems would carry approximately 15 percent to more than 25 percent of the total person trips during peak summer and winter recreation travel at the Twin Tunnels. For example, the transit share for winter Saturday westbound recreation travel at the Twin Tunnels would be about 25 percent to 28 percent for the Transit alternatives (Rail, AGS, and Bus in Guideway alternatives), and about 20 percent for the Combination alternatives (Six-Lane Highway with Rail, AGS, or Bus in Guideway transit systems). These percentages would equate to about 29,000 transit person trips for the Transit alternatives (and about 73,000 person trips on the highway) on a winter Saturday in 2025.