6.0 CONGESTION HOT SPOT PROBLEM AND IMPROVEMENT TRAVEL DEMAND MODEL ANALYSIS

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1 6.0 CONGESTION HOT SPOT PROBLEM AND IMPROVEMENT TRAVEL DEMAND MODEL ANALYSIS 6.1 MODEL RUN SUMMARY NOTEBOOK The Model Run Summary Notebook (under separate cover) provides documentation of the multiple travel demand model runs and resulting forecasts that have been developed during the course of the Congestion Hot Spots Study for the SR-91/I-605/I- 405 in the Gateway Cities. The forecasts are the output of a travel demand model that estimates traffic volumes by vehicle class (e.g., drive-alone, shared-ride, and trucks) for a network of highway and roadway links of interest in the study area. The computer model is based on the TransCAD platform and it produces traffic forecasts for four different time periods, which together constitute average daily traffic volumes. Additional techniques outside of the model are applied to estimate peakhour traffic volumes for different times of the day. The traffic forecasts provided critical inputs for a number of subsequent engineering and analysis tasks: The traffic forecasts are inputs to traffic operations analysis that characterizes traffic flow conditions and is used by the design engineers to evaluate the geometric design of different alternatives for freeway, ramp, and arterial improvements. The traffic forecasts form the basis of defining traffic circulation impacts and benefits of improvement alternatives. Forecasts were used to assess implications of other improvements and programs including multi-modal projects, travel demand management, intelligent transportation systems and all other known or foreseeable transportation projects that could affect the study area s transportation system. A separate report was reviewed and approved by the project Technical Advisory Committee entitled I-605/SR- 91/I-405 Congestion Hot Spots Travel Demand Model Methodology and Validation Report. That report described the model components, key input assumptions, as well as the validation of the model to ensure that it accurately replicates area traffic conditions. The purpose of the Notebook is to provide further detailed description of the model run history and to help the reader understand the relationship of the various runs to each, and what types of information the runs produced. In addition to these two reports, the model results have been documented in a series of detailed technical memorandum on various subjects including the impacts and benefits of added freeway mainline capacity, realigned and modified arterial ramp interchanges, potential freight corridors, multi-modal improvements, express lanes, HOV to HOV connectors and other transportation projects within and adjacent to the study area. The appendix to the Notebook includes various technical memos on these topics that were developed during the course of the study, along with the model validation report which describes the model validation process and model runs conducted during validation. Page 67

2 The model data has also been used throughout the study by the geometric team to help assess congestion hot spots as well as to assess the benefits of a series of geometric improvements as part of Concepts A, B, C and variations of those Concepts. The travel model was used to forecast demand levels for all of the roadways and highways in the study area, providing input to the design of freeway, arterial intersection, and ramp improvements. Travel forecast data are also used by traffic engineers to determine whether the various design concepts will be sufficient to relieve bottlenecks and resolve safety hazards (and to what extent). The Notebook documents 18 model runs that were undertaken during the course of the project. The model runs are numbered 1 through 20, however, a total of 18 unique runs are included in the documentation. Two of the runs were deferred and not used until later in the process, however for clarity the numbering scheme remained consecutive since all of the models were assigned their unique model run during the course of the analysis. It should be noted that many other model runs were also made, such as numerous model validation runs as well as numerous runs conducted during the development of geometric Concepts A, B and C. Those are not documented herein because they are considered testing runs and were conducted for purposes of interim analysis leading up to the final Concept design recommendations. The Notebook provides a summary of each model run, its application, and key run assumptions for the highway network, transit network and modal split. 6.2 MULTI-MODAL ANALYSIS The objectives of the Multi-Modal Analysis Report (under separate cover) are to assess the existing, future, or potential capabilities of alternative modes of transportation to reduce or relieve or impact traffic on freeway and arterial facilities within the SR-91/I-605/405 Congestion Hot Spots study area, as well as to understand the relationships between various multi-modal improvements. To set the stage for this multi-modal analysis, existing and proposed transit system and other modes of transportation data and information were collected and summarized for the study area, for the Gateway Cities and in some cases beyond the Gateway Cities. This includes an in-depth review of existing, future or potential transit capacities, seats, ridership, demographics, trip share, system constraints, and capabilities. The following modes of transportation and transportation programs were evaluated as part of this effort: Local and Regional Bus Transit Services Non-Motorized Facilities Rail Transit High Speed Rail Park and Ride Facilities High Occupancy Vehicle Lanes Toll Facilities Goods Movement Page 68

3 Intelligent Transportation Systems Trip Reduction Programs/ Travel Demand Management Arterial Highways A maximum investment scenario analysis has been developed, which includes all of the planned transportation improvements in and around the Gateway Cities, in order to determine the potential effect on the transportation system of investment in other modes and programs beyond those already funded (No-Build conditions). The potential for other modes to affect travel and reduce congestion in the study area was examined for three types of outcomes: 1) Reducing study area internal auto trips via shifting them to other modes 2) Reducing through auto trips via shifting them to other modes 3) Other mobility improvements such as shifting trips to other facilities (e.g. truck/freight corridors, HOV lanes) from general purpose freeway lanes and reducing vehicle delay (Intelligent Transportation Systems or Toll facilities) As noted, two types of trips are studied as part of the multi-modal analysis; 1) internal trips which have an origin or destination (or both) within the Gateway Cities and 2) external trips that pass-through the area but have neither a beginning nor end in the Gateway Cities (such as a freeway trip from Orange County to Downtown Los Angeles). It is important to understand that some multi-modal projects and improvements mainly affect trips with one or both ends of the trip inside the Gateway Cities, while others primarily affect through trips and some affect both internally generated trips as well as through trips. Information and data for specific improvements were obtained from project study documents including alternatives analysis, environmental documents, feasibility studies and regional plans. The data was compiled and quantified in terms of the number of person trips each improvement could transport in lieu of vehicle trip, and to the extent feasible the information is presented for internal trips versus through trips. 6.3 APPLICATION & ASSESSMENT OF OTHER TRAVEL MODEL SCENARIOS The geometric concept levels of service (both HCM and travel demand model) are based on prior model runs which include the concept geometric improvements plus selected (mostly funded and foreseeable) multi-modal transportation improvements in the study area and that affect the study area. They do not, however, reflect the results of the final multi-modal model runs (runs 19 and 20). The final runs estimate the benefits of the Maximum Investment scenario for multi-modal improvements and programs on study area freeways. Model Runs 19 and 20, the Maximum Multi-modal Investment Scenario model runs, add many potential multi-modal projects beyond what is included in the Concept A, B and C model runs Page 69

4 and associated analyses. Specifically, for Model Run 19, additional highway system improvements include HOV connectors, I-405 Express lanes, and Intelligent Transportation System improvements throughout the study area. Also included in Model Run 19 beyond Concepts A, B and C is assumed maximum investment in transit services including the potential Pacific Electric Right of way/west Santa Ana Branch rail line, High Speed Rail and maximum increases in Metrolink, Amtrak and local bus services. Model Run 20 includes the same assumed maximum investments as Model Run 19, plus the potential East/West Freight Corridor project, the proposed Southern California Intermodal Gateway (SCIG) project and the proposed Intermodal Container Transfer Facility (ICTF) capacity improvement project. These potential projects were tested using the model to determine what additional benefit they would have if implemented together on the local area freeway and roadway system in terms of reduction in automobile travel in the system, and commensurate reduction in vehicle miles travelled, motorist delay and vehicle hours of travel and increases in system operating speeds. For the entire study area, the Maximum Multi-modal investments would be expected to benefit the freeway and arterial system via reductions in vehicle miles travelled and vehicle delay during peak hours. On the freeway system, an aggregate reduction in VMT (beyond Concept B) of two percent is projected. That is, the effects of the Maximum Multi-modal investments would result in a net reduction of approximately two percent of the volume on the study area freeway system overall. It is important to note that the actual gross overall reduction in volume due to Multi-modal investments would be greater than two percent, but there would then be diversion of trips back to the study area freeways, thus resulting in a lower net reduction in volumes. This is because by 2035 most of the freeways in the vicinity of the study area would operate at very poor levels of service (and many arterials as well), and thus removing traffic from the study area freeways would free-up roadway capacity that would then be used by trips shifted from other parallel routes. In terms of motorist delay, the Maximum Multi-modal investments would be expected to result in an additional incremental benefit of about ten percent reduction delay on the freeways. The reduction in freeway delay is much larger than the reduction in VMT because delay is already high on congested facilities and removing even some VMT will result in a disproportional benefit in reduced delay on the system. On the arterial highway system, the vehicle miles travelled would also be expected to decrease. This is due to the effects of the multi-modal improvements as well as the additional freeway capacity which can then serve some of the arterial traffic. On the arterial system, the VMT is expected to decrease about three percent beyond Concept B. As with freeway conditions, the vehicle delay is expected to be reduced by about ten to eleven percent beyond the level of reduction due to the Concept B improvements alone. In terms of specific freeway locations, the assigned traffic volumes will decrease by different amounts due to the effects of the Maximum Multi-modal investments. For example, the Page 70

5 PEROW will affect some freeway segments more than others, and increases in other transit services will affect some areas more than others. Route by route descriptions of the affects of the Maximum Multi-modal scenario are provided below. The SR-91 problem definition areas have been reviewed against the final model runs to determine if the run results would significantly affect the problem definition and thus ultimately the recommended improvements. The final model run results indicate the following for SR-91: East of I-605 the final multi-modal analysis indicates that an additional reduction of approximately 6,000 daily vehicles from the mainline due to the maximum multi-modal investments (a reduction of two percent of 2035 volume). Peak period average speeds on this portion of SR-91 are expected to increase by one to two miles per hour. Between I-605 and I-710 up to approximately 13,000 vehicles (a reduction of four percent of the 2035 volume) per day could be reduced due to multi-modal investments. Peak period average speeds on this portion of SR-91 are expected to increase by about two to three miles per hour. The I-605 problem definition areas have been reviewed against the final model runs to determine if the run results would significantly affect the problem definition and thus ultimately the recommended improvements. The final model run results indicate the following for I-605: South of SR-91 the final multi-modal analysis indicates that an additional reduction of approximately 5,000 daily vehicles from the mainline due to the maximum multi-modal investments (a reduction of two and one half percent of 2035 volume). Peak period average speeds on this portion of I-605 are expected to increase by up to one mile per hour. Between SR-91 and I-5 up to approximately 15,000 vehicles (a reduction of four percent of the 2035 volume) per day could be reduced due to multi-modal investments. Peak period average speeds on this portion of I-605 are expected to increase by up to three miles per hour. North of I-5 the final multi-modal analysis indicates that an additional reduction of approximately 7,500 daily vehicles from the mainline due to the maximum multi-modal investments (a reduction of two percent of 2035 volume). Peak period average speeds on this portion of I-605 are expected to increase by up to two miles per hour. The I-405 problem definition areas have been reviewed against the final model runs to determine if the run results would significantly affect the problem definition and thus ultimately the recommended improvements. The final model run results indicate the following for I-405: Page 71

6 The final multi-modal analysis indicates that an additional reduction of approximately 9,500 daily vehicles from the mainline due to the maximum multi-modal investments (a reduction of three percent of 2035 volume). Peak period average speeds on this portion of I-605 are expected to increase by up to three miles per hour. In summary, with the maximum potential investment in other multi-modal projects and programs it is expected that the hot spots on all freeway segments would be improved. Daily volume reductions are projected to range from about 5,000 up to 15,000 vehicles per day, depending on freeway location and how each location is affected and benefits from the Maximum Multi-modal investments scenario. This equates to a percentage reduction in ADT of one to four percent, again varying by location. The greatest benefits are seen on I-605 north of SR-91 and on SR-91 west of I-605. The level of improvement is not sufficient to eliminate significant congestion points or eliminate the need for physical improvement via the any of the corridor concepts (Concept A, B & C), but it would likely cause improvements in the final level of service, operating speeds and other conditions. Implementation of the full range of multimodal improvements could also affect the final design once the refined volumes and further detailed analyses are completed. Page 72