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Travel Demand Considerations 51 Exhibit 5-6. Elasticity values for different methods of computation. Fare Change Log Arc Midpoint Arc Shrinkage (%) Elasticity Elasticity Factor -50 -0.300 -0.311 -0.46 -30 -0.300 -0.303 -0.38 -10 -0.300 -0.300 -0.32 +10 -0.300 -0.300 -0.28 +30 -0.300 -0.302 -0.25 +50 -0.300 -0.311 -0.23 +100 -0.300 -0.311 -0.19 Source: Calculated Exhibit 5-7. Typical midpoint arc elasticities. Bus Item Travel Time Bus Miles Frequencies New routes replace or Greater Service Application complement existing frequency of expansion routes existing routes Range -0.3 to -0.5 0.6 to 1.0 0.3 to 0.5 Typical -0.4 0.7 to 0.8 0.4 Source: TCRP Report 99 (18 ) Assume that travel times to the rapid transit station decrease from 12 to 10 minutes as a result of a service improvement to feeder transit service. The following changes in ridership are anticipated based on an elasticity of -0.35 and a base ridership of 1,000. By the shrinkage factor method: ( -0.35)(1, 000)(10 - 12) R2 = 1, 000 + = 1.058 = 5.8% 12 By the midpoint arc elasticity method: ( -0.35 - 1)(12)(1, 000) - ( -0.35 + 1)(10)(1, 000) R2 = = 1, 066 = +6.6% ( -0.35 - 1)(10) - ( -0.35 + 1)(12) Estimating Ridership for New and Infill Stations Estimating ridership for new stations as well as infill stations is normally done for future plan- ning or horizon years. The process requires knowledge of existing travel patterns and reasonable estimates of future population, employment, and land development. Estimates can be made either by using this report's station ridership model and access planning tool (or an agency-specific model) or using a traditional four-step model using trip generation, trip distribution, modal allocation, and trip assignment to transit and highway networks. When a four-step model is used, the model should be calibrated for both the transit and automobile

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52 Guidelines for Providing Access to Public Transportation Stations modes, and the model's network design should include highway and transit links and a means to model multi-modal trips, such as park-and-ride. The modal allocation of travel is a major concern in rapid transit demand estimation. Most regional planning agencies use a logit model to estimate mode splits. Logit models assume that the share of trips by a specific mode is a function of the mode's utility (i.e., attractiveness to passengers, based on various user and system characteristics such as vehicle ownership, travel time, and price) divided by the sum of the utilities of all possible modes for the trip. Ratio Method for Infill Stations In addition to the methods described, a simple ratio method may also prove to be a valuable tool in estimating demand for infill stations. This method works by assuming that the proposed station will have similar relation of ridership to surrounding land uses. To apply this method, information should be assembled on the population, demographic, and development characteristics for an area within to 1 mile of the proposed station and the two adjacent stations. Exhibit 5-8 summarizes the information that should be assembled. Basic information should be compared for the proposed station and the two existing adjacent stations. These key comparisons include total population, resident workers, and employment in the station areas. The catchment area characteristics of the proposed station should be compared with those of the two adjacent stations. The ratios of ridership to the key demographic factors (i.e., population, workers, and employment) can be determined for the two existing stations and then applied at the proposed station to estimate number of boardings. Exhibit 5-9 provides an illustrative example. The new station ridership can be expressed as either a range or as average. The analysis may also be extended to also estimate mode split and parking demand. Exhibit 5-8. Desired station profile information within -mile radius of existing and proposed stations. Station Characteristics Station Area Demographics Status Population Rapid transit mode Workers Station type Jobs Predominant Land Use Median household income Topography Percent zero-car households Vehicles per worker Access Provisions Daily parking spaces (at the station) Reserved parking spaces Daily and monthly parking rates Parking occupancy at 9 am Bicycle parking spaces Round trip transit fares Connecting transit lines Transfer charge (if any)

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Travel Demand Considerations 53 Exhibit 5-9. Illustrative computations for estimating boardings at a proposed station. Existing Station A Proposed Station Ratio Boardings 4,000 boardings X Population 10,000 population 8,000 0.80 Employment 6,000 workers 5,000 0.83 x 0.80 * 4,000 = 3,200 x 0.83 * 4,000 = 3,320 Existing Station B Boardings 6,000 boardings X Population 16,000 population 8,000 0.50 Employment 9,000 workers 5,000 0.56 x 0.50 * 6,000 = 3,000 x 0.56 * 6,000 = 3,360 Exhibit 5-9 shows that the proposed station could have daily boardings of between approximately 3,000 and 3, 400. This ratio or interpolation method requires that the land uses at the proposed stations are similar to those at adjacent stations. When this is not the case, the characteristics for the planned station should be compared with those for stations elsewhere in the system with similar uses. Note that this method assumes all of the ridership at the infill station consists of new riders. In practice, this is unlikely to be true, and analysis of infill stations should consider the potential that an infill station will simply re-distribute existing ridership rather than generate new riders.