3 Palmer Urban Travel Demand Model Development

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1 3 Palmer Urban Travel Demand Model Development This section discusses the development of the urban travel demand model. The Palmer Urban Transportation Study includes a detailed demand model for the Palmer area. The model horizon year (planning year) is Under travel demand modeling, the home is the primary trip producer, which would include home based work trips (home to work and then work to home) and home based other trips, for example home to shopping then shopping to home. Trip attractions in the aforementioned example would be work places and retail stores, but may include other activities such as recreation or school. If a production or attraction activity is not well described by standard model parameters, then special generators may be established. The trips are distributed between productions and attractions based upon the anticipated size and proximity of employment, retail, and institutional attractions to residential areas, the model then assigns a route to each trip that minimizes the travel time for that trip. Summing the trips along each route produces the travel demand, which can be expressed in vehicles per day. This work consists of the development of two types of models. The first model type is an existing conditions (base year 2005) model from which calibration and validation is determined. This model is critical because it is assumed that if the existing conditions model can accurately replicate current traffic demand, then the model variables can be reset to future year conditions and the future year traffic demand will also be accurately predicted. Validation of the existing condition s model consisted of comparing predicted traffic volumes against measured traffic volumes. Calibration consisted of adjustment to the model parameters to better match the measured traffic volumes. The second model type that is developed in this section is the Future 2025 models for each alternative roadway network. Each of these models are modified versions of the validated 2005 model, adjusted to reflect the forecasted development and committed Palmer Urban Traffic Study Page 46 Kinney Engineering

2 and alternative system improvements. In general, these models retain the same future development and differ only in the transportation network. Finally, this section assesses the lane and intersection requirements at the planning level and adjusts the future year models accordingly before proceeding into more refined analysis. 3.1 Model Context The MSB retained HDR to update/prepare a Borough-wide demand model as part of the LRTP effort. HDR used the TransCad platform, since it could be integrated with the Municipality of Anchorage model (their model is also TransCad), and present a regional demand model. This approach provides a good forecast for higher-mobility facilities. Generally, interstate, expressway, and arterial class roadways are reasonably well-modeled. However, collector model outputs can be highly variable compared to actual observations, and local streets have such a high degree of variation that they are usually not included in the model network. The inaccuracies of the lower functional group streets are not an indication of model deficiency, but rather model focus. The demand models are typically used to define new corridors and corridor improvements; and therefore inaccuracies on lower-mobility streets are usually due to model construction. As an example, Figure 16 shows traffic analysis zones summary of generators that cover a large land area with only a limited connection to the network. This configuration will adequately load the major corridors, but is likely to not do so for the local or minor collector streets. The focus of this study is to study east-west circulation alternatives. It was determined that additional east-west capacity improvements within Palmer would require a micromodel that would operate within the larger framework of the LRTP model. The micromodel would include a more detailed street system and distribute traffic generators to more closely represent current land use and potential development. Palmer Urban Traffic Study Page 47 Kinney Engineering

3 3.1.1 Four Step Travel Demand Process Travel demand models follow a four-step process including trip generation, trip distribution, modal split, and trip assignment. Typically, each of these steps uses source documents, and classical methods and algorithms that extend across proprietary models. Trip Generation: There are trip types in this model; home-base-work, homebased-other, and non-home-based. Home-based trips are produced by households, with unit rates being a function of income levels and auto-ownership, and are independent of actual origin or destination. Non-home based trip production and attraction are determined from generator activity. Trip Distribution: Trips produced in one zone are attracted to another zone in a methodology analogous to gravity in which the pull between objects is a function of their respective mass and the separation distance. More trip making activities available in a zone, for example households or employees, results in a greater mass of the zone. Similarly, zones that are closer to one another are more likely to produce and attract trips between one another, rather than ones that are further away. In addition to inter- and intra-zonal travel, there will be trip exchange between productions and attractions that are outside of the study area. These are addressed by an external station that is positioned at the end of a road at the edge of the model area. The external station attributes are approximated by current or future forecasted AADT. Modal Split: Person-trips generally have several mode choices including a private automobile, transit, or as a pedestrian. Table 14 summarizes the 2000 census transportation to work within the urban Palmer area. As shown, passenger vehicles are the dominate mode split by a wide margin for homebased work trips. Palmer Urban Traffic Study Page 48 Kinney Engineering

4 Mode used for Work Trips 2000 Palmer Urban Area Car, truck, or van 1498 Bus or trolley bus 53 Walked 91 Other means 55 Worked at home 100 Total 1797 Source: _SF3_U&_lang=en&_ts= Table Census Means of Transportation to Work for Workers 16 Years and Over Current and future public transportation opportunities include: MASCOT (see Section 2.4.2, 2006 ridership was 72,000); Ride-share between MSB and Anchorage (the LRTP states 675 people from MSB, inclusive of Palmer, were carpooling); and, Potential rail commuting service (the LRTP cites a 2002 study about feasibility requirements and investment, two levels of service, with 150,000 to 170,000 initial annual ridership, with about 80% of costs subsidized). The LRTP recommends advancing public and non-vehicular modes of travel. However, it is not clear as to the forecasted benefits of alternative transportation. As such, this study assumes that non-automotive travel modes are unlikely to alter the alternatives during the period studied. This assumption is consistent with the goal of improving the area s limited road network by estimating the highest level of person-trips by automobile and the highest automobile demand, which produces the most conservative models for alternative development. Trip Assignment: Trips are assigned paths so that the travel costs are minimized between zones. There are several methods to do this, but in general aggregate Palmer Urban Traffic Study Page 49 Kinney Engineering

5 zone to zone trips are iteratively assigned to links, with costs (usually travel time) updated until link volumes converge on the minimum cost solution. 3.2 Palmer Urban Transportation Study QRSII Parameters Trip Generation and Traffic Analysis Zones As discussed under Section MSB LRTP Socio-Economic Model Parameters, the LRTP model socio-economic parameters are reasonable for Palmer. As such, trip generation quantities (households and employment) were retained from the LRTP model and used for this micro model. The TAZ provided by the LRTP demand model were divided into smaller zones and distributed across the LRTP TAZ area in a manner that would correspond to current and/or future development. For future development in the 2025 model, it was determined that some of the TAZ forecasts were not compatible with land availability or the zoning (Figure 5). In those cases, development aggregate levels were maintained at the LRTP levels, but were distributed to other more viable zones. The result was that the Palmer Urban Transportation Study QRSII model overall had very similar levels to the Palmer area LRTP model (see Table 11 and Table 12). External stations (boundaries) for the Palmer urban demand model used the existing AADT for the 2005 base model, and the LRTP forecasted AADT for the 2025 model Future Street Network (Existing and Committed) The 2025 LRTP base-level network, without the Knik Arm Crossing, was used as the basis of this study, augmented with an extension of Hemmer Road north beyond the PWH to a future Bogard Road. This study does not attempt to model the entire future road network as described in the Borough LRTP Needed Improvements since all improvements could not be assumed to be in place in 2025 with a reasonable certainty. For example, both the Borough LRTP Needed Improvements list and the Palmer Comprehensive Plan show Hemmer Road extending north to Palmer-Fishhook Road. Palmer Urban Traffic Study Page 50 Kinney Engineering

6 While the improvement is needed, basing this study on the assumption that the road will be in place in 2025 is not considered reasonable. During a December 2006 discussion between representatives of Kinney Engineering, LLC, ADOT&PF, the City of Palmer, and the Matanuska-Susitna Borough, it was determined that extending Hemmer Road north of the PWH to Bogard Road was in keeping with the concept that the base-level network should be expected to exist in 2025 with reasonable certainty. As a result, the 2025 traffic models include the following additions to the existing street network: Glenn Highway will be a four-lane arterial/highway from the Parks Highway to Palmer Fishhook Road. The Glenn Highway speed through Palmer will be 45- mph. Bogard Road will be extended from the 49th State Street to the Glenn Highway as a 35-mph (or higher speed) two-lane facility and upgraded in functional classification to a Minor Arterial. Hemmer Road will be extended from the Glenn Highway to the PWH as a 40- mph two-lane minor arterial. Hemmer Road will be extended from Arctic Avenue to the Bogard Road extension, so that a continuous 35-mph, two-lane collector will be completed between the PWH and Bogard Road. Felton Road will be added as a two-lane facility (25-mph, local street) from the Arctic/Bogard extension to the PWH. Dogwood Street is added as a two-lane facility from south Alaska Street to Felton Street. The PWH will be a 45-mph four-lane Major Arterial highway with left turn treatments to the east of Hemmer Road. Palmer Urban Traffic Study Page 51 Kinney Engineering

7 3.2.3 Calibration and Validation Calibration verified that street conditions (lanes, intersection control) were represented by the 2005 Palmer QRSII model trip generation parameters from Table 12 were redistributed to existing businesses located in the field and from aerial photographs. Volume counts at existing intersections were considered, and volume counts at major generators were used to calibrate special generators. Validation consisted of adjusting the QRSII capacities, speeds, trip production tables and the splits between productions and attractions within the network and at external stations until the model trips matched ADOT&PF counts within allowable deviation limits per roadway classification. The model link volumes for major roadways in the model were averaged and divided by the average of ADOT&PF counts for the same links. Federal Highway Administration (FHWA) has recommended error limits for aggregated functional classification roadways (total model link volumes by class divided by total link ground counts by class) as follows: Freeways: ±7% Principal Arterials: ±10 Minor Arterials: ±15% Collectors: ±25% Frontage Roads: ±25% Table 15 summarizes the calibrated and validated 2005 QRSII model volumes for key links and compares these to the 2005 link AADT shown in Figure 7,and other MSB volume estimates. Palmer Urban Traffic Study Page 52 Kinney Engineering

8 Street Segment Class AADT Model AADT % Error Alaska Way Collector 4, % Arctic Avenue East of Airport Collector 7, % Arctic Avenue Airport-Denali Collector 8, % Arctic Avenue S Valley to Alaska Collector 9, % Arctic Avenue Alaska-Glenn Collector 10, % Chugach Street Outer Springer Loop to Fireweed Collector 3, % Chugach Street Fireweed to Elmwood Collector % Colony Way Glenn to Fireweed Collector 2, % Dahlia Avenue Valley to Denali Collector 1, % Dahlia Avenue Denali to Gulkana Collector 1, % Evergreen Street Near Glenn Collector 12, % Evergreen Street Gulkana to Airport Collector % Gulkana Street Evergreen to Dahlia Collector % Hemmer Road Arctic to PWH Collector 2, % Inner Springer Loop Glenn to ISL Collector 2, % Inner Springer Loop Collector 1, % Outer Springer Loop ISL to Chugach Collector 2, % Valley Way Dahlia to Arctic Collector 1, % Valley Way Elmwood to Dahlia Collector 3, % Average -9.29% Weighted Average -7.28% Standard + or - 25% Street Segment Class AADT Model AADT % Error Glenn Highway ISL to Colony Prin. Arterial % Glenn Highway Colony to PWH Prin. Arterial % Glenn Highway PWH to Arctic Prin. Arterial % Glenn Highway Arctic to Scott Prin. Arterial % Average -4.00% Weighted Average -4.17% Standard + or - 10% Street Segment Class AADT Model AADT % Error Palmer Wasilla Hwy Hemmer to Glenn Min. Arterial % Standard + or - 15% Table Model AADT and Actual AADT-Validation Results Palmer Urban Traffic Study Page 53 Kinney Engineering

9 As Table 15 indicates, the 2005 base QRSII model was within FHWA tolerances. The validated 2005 micro-model was then updated to include the 2025 committed network improvements described in Future Street Network, as well as the 2025 Socio-Economic data presented in Table 11. The trips generated were redistributed in accordance with the modified development patterns that are more closely aligned with zoning as discussed under Section At this point, the resulting model was the committed network alternative. 3.3 Alternative 2025 Model Development and Refinement Process Figure 17 provides an overview of the demand model process, and encompasses all of the elements discussed under the preceding sections of this report. Data Collection Construct Base Model Structure, 2005 Street Network Research Socio- Economic Conditions: Compare MSB LRTP 2000 Model Parameters to Census Populate Model Structure with Productions/Attractions Calibrate and Validate Base Model Output to 2005 AADT 2025 Socio-economic LRTP, Add committed links Model No Action Alternative Begin Iterative Refinement Model Build Alternatives Begin Iterative Refinement Figure 17 - Travel Demand Model Process Steps Palmer Urban Traffic Study Page 54 Kinney Engineering

10 Figure 18 summarizes the alternative refinement process. For Each Alternative Input Lanes (Capacity) and Intersection Control Run Model Check Intersection Control Assumptions (CAL-TRANS Warrant) Check Roadway Capacity (Screen line and HCM Planning) Lanes and Control Needed Match Input? Performance OK? Model Done Evaluate Roundabout Options Figure 18 - Alternative Model Refinement Process Elements and steps within the process that are bold and highlighted are discussed in more detail in the following sections Future Intersection Control Signal Warrants Generally, signals should only be considered for intersections if one or more warrants established by the Manual of Uniform Traffic Control Devices (MUTCD) are satisfied. The warrants include: Warrant 1 - Eight-Hour Volume (conditions A, B, and 80% of A and B combined) Warrant 2 - Four-Hour Volume Palmer Urban Traffic Study Page 55 Kinney Engineering

11 Warrant 3 - Peak Hour Volume Warrant 4 - Minimum Pedestrian Volumes Warrant 5 - School Crossings Warrant 6 - Coordinated Signal System Warrant 7 - Crash Experience (five or more correctable crashes in a 12-month period, and volume criteria) Warrant 8 - Roadway Network These warrants require current vehicle and pedestrian volumes, speeds, and crash history. The warrants are evaluated in accordance with MUTCD procedures for these inputs, augmented with engineering judgment that considers area planning and adjacent intersections. Seventy percent of volume warrant values from the MUTCD apply if an intersection is located in a rural area. The MUTCD warrant system for new signals evaluates recent or current conditions. Cal-Trans has a methodology for future signal warrants that is presented in the ITE Manual of Traffic Signal Design, Second Edition, by James H. Kell and Iris J. Fullerton. The method uses future estimated average daily traffic as the input variables and estimates whether the intersection with future estimated average daily traffic would meet the Manual of Uniform Traffic Control Devices Signal Warrant 1, Condition A - Minimum Vehicular Volume; Condition B - Interruption of Continuous Traffic; and the combination of warrants allowed in MUTCD procedure. The warrant is applicable to rural and urban conditions, with rural volume thresholds at 70% of urban values. The MUTCD signalization warrants use an area population of 10,000 as the minimum population threshold for urban areas. Since the Palmer population will be below 10,000 for most of the study period, the rural warrant volumes are applied for modeling. As such, the rural assumption lowers the volume warrant levels for signals and makes it more likely that signals will be used in the model. However, it should be recognized that Palmer land use and traffic volume levels will Palmer Urban Traffic Study Page 56 Kinney Engineering

12 resemble urban conditions over a larger area. Therefore, when it becomes time to evaluate signal controls, the assumption of rural conditions should be re-evaluated. Table 16 summarizes Cal-Trans entering ADT volumes for warrant levels. Warrant 1 - Minimum Vehicular Warrant 2 - Interruption of Continuous Traffic Warrant 3 - Combination Major Road Lanes Minor Road Lanes Major Road (Total Entering ADT) 5,600 5,600 6,720 6,720 Minor Road (Highest Approach 1,680 2,240 1,680 2,240 Entering ADT) Major Road (Total Entering ADT) 8,400 8,400 10,080 10,080 Minor Road (Highest Approach Entering ADT) Major Road (Total Entering ADT) Minor Road (Highest Approach Entering ADT) Table 16 - Future Signal Warrants, Rural Conditions 850 1, ,120 80% Levels of 1 & 2 AADT volumes are the input variables for this method, and signalization causes travel delay which affects the traffic volume route assignment. It is necessary to re-evaluate the warrants following the run to ascertain if the intersection should be signalized Planning Capacity Analysis Screen Line Segment Level of Service Planning-level capacity analysis was performed at appropriate steps in the model process to estimate lane requirements for the alternatives. The Florida Department of Transportation Quality/Level of Service Manual provides a planning-level capacity analysis methodology that uses lanes, road class, and signal spacing to estimate the planning level of service. This manual was the basis for planning level ARTPLAN Palmer Urban Traffic Study Page 57 Kinney Engineering

13 module additions to the Highway Capacity Software, HCS+. summarizes the Florida information used for this study. The following table Class I (>0.00 to 1.99 signalized intersections per mile) Lanes/LOS A B C D E 2 4,200 13,800 16,400 16, ,800 29,300 34,700 35, ,300 44,700 52,100 53, ,400 58,000 66,100 67,800 Not Applicable, intersections control and volumes below D levels indicate F Class II (2.00 to 4.5 signalized intersections per mile) Lanes/LOS A B C D E 2 1,900 11,200 15,400 16, ,100 26,000 32,700 34, ,500 40,300 49,200 51, ,500 53,300 63,800 67,000 Class III (more than 4.5 signalized intersections per mile) Lanes/LOS A B C D E 2 * 5,300 12,600 15,500 4 * 12,400 28,900 32,800 6 * 19,500 44,700 49,300 8 * 25,800 58,700 63,800 These values are base conditions. Per the manual, level of service volumes are reduced if there are no left-turn treatments at intersections, and increased for divided roadways (cumulative change -25% to +5%). Decrease corresponding two-directional volumes in this table by 40% to obtain the equivalent one directional volume for one-way facilities. Table 17 - Planning Level of Service for AADT on Various State Two-Way Arterials This method should be used with caution. It has a range of assumptions, of which all are not likely satisfied for any analysis. With respect to this project, one of the method s assumptions that is not true is that there are balanced green times between the analyzed street and its cross-streets, which will not be the case for minor streets intersecting the Glenn Highway or the PWH. Palmer Urban Traffic Study Page 58 Kinney Engineering

14 Intersection Planning Capacity Analysis For the last iterations of the build alternatives, the turning movement volumes were extracted from the QRSII model, and these volumes input into the Highway Capacity Manual 2000, (Highway Capacity Software or HCS2000) intersection planning application. This step was used to verify that the alternative would have adequate capacity and could be advanced to the next stage of the study. HCS2000 reports quality of operations as an intersection volume to capacity ratio and provides a qualitative performance described as under capacity, near capacity, at capacity, and over capacity. From the planning perspective, under capacity is desirable, and near capacity may be acceptable conditions. At capacity or over capacity conditions are generally not acceptable. Roundabouts are increasingly being used as alternatives to signalization. A roundabout has good operational performance, excellent crash and severity reduction performance, and has no signal control maintenance and operations burden and liability in the case of failure. ADOT&PF has observed that roundabouts may be appropriate at several PWH intersections, specifically Hemmer Road in this study area (per memorandums from Thomas to Keith, September 12, 2005 and March 14, 2006). During interim progress reviews of this study, the State indicated that the Glenn/Palmer-Wasilla/Evergreen and Glenn/Dogwood, and Glenn/Arctic intersections should be candidates as well. In addition, all new intersections created by the alternatives were reviewed for roundabout feasibility. Palmer Urban Traffic Study Page 59 Kinney Engineering