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Heffron Transportation Inc - Preliminary Treip Generation Analysis062609.pdfheffron TECHNICAL MEMORANDUM Project: Edmonds Shopping Center - Redevelopment Project Subject: Preliminary Trip Generation Analysis Date: June 26, 2009 Author: Michelle M. Br . n, Senior Transportation Engineer Marni C. Heff 2 .E., Principal Engineer This memorandum presents the trip generation estimates for the Edmonds Shopping Center redevelopment project. 1.. Proposed Project The project proposes to redevelop the existing S 1,124 square foot (so retail mall located south of the Edmonds Ferry Terminal. It would demolish the existing mall and construct both commercial (30,302 sf) and residential (up to 360 units) spaces. The project program is summarized in Table 1. Table 1. Edmonds Shopping Center Proposed Redevelopment Land Use Planned Development Commercial 30,302 sf Restaurant 10,100 sf Retail 20,102 sf Residential 286 to 360 units Condominiums 106 to 144 units Apartments 180 to 216 units Parking 423 spaces Residential 331 spaces Commercial 92 spaces Source: UB! Group, June 11, 2009. 2. Trip Generation Methodology Trip generation for the proposed Edmonds Shopping Center Redevelopment Project was estimated using rates published by the Institute of Transportation Engineers and a methodology that accounts for the project's mix of uses and location near major transit facilities. The following briefly defines the methodology used to determine the trip generation: W Edmonds Shopping Center Redevelopment Project h e f f r o n Preliminary Trip Generation Analysis 1. The total number of "person trips" generated by the proposed uses was determined using trip generation rates and equations from the Institute of Transportation Engineers (ITE) Trip Generation, plus information regarding the average number of persons per vehicle. These person trips reflect all modes of travel to the site including transit, bike, and foot. It also includes the trips that would be made between on -site uses (internal trips). 2. Internal trips between on -site uses were determined using the methodology in Chapter 7 of the Trip Generation Handbook (ITE, June 2004). Examples of internal trips would include a resident who makes a morning or evening trip to the retail or restaurant. All of the internal trips at this site would be expected to be made by foot, so they would not create vehicle trips. Some of the commute trips are expected to be made by non -automobile modes of travel (transit, train, bicycle or walking). For this site vicinity, Puget Sound Regional Council (PSRC) provided data showing non -automobile rates of 10% based on year 2000 Census surveys. This rate was used; however, it is expected the non -automobile rate would be higher for the proposed residences since they would have direct access to the Sound Transit Commuter Rail Station, which was not yet built when the latest Census was performed. The remaining 90% of the trips were assumed to be made by single -occupant vehicles or carpools. Mode of travel assumptions are detailed in Section 4 below. 4. The commercial trips (retail and restaurant) were divided into three trip types —pass -by trips, diverted -linked trips, and primary trips —using information from the Trip Generation Handbook. Further information related to various trip types is described in Section 4 below. All of the assumptions listed above were used to determine the number of trips that would be generated by buildout of the site. Key information from these calculations includes vehicle trips, transit trips, and pedestrian/bicycle trips. This same retail mode splits and trip types were used to calculate the existing trip generation for the site. Although internal trips are likely to occur within the existing retail mall, no reductions were assumed since the retail space is assumed as one entity. The difference between the existing and proposed trip generation results in the net increase in traffic due to the proposed project. Rates and equations found in Trip Generation (Institute of Transportation Engineers [ITE], 8th Edition, 2008) were used. For the existing and proposed retail uses, "Shopping Center" (Land Use Code 820) rates were used. "High -Turnover Restaurant' (Land Use Code 932) rates were used for the proposed restaurant. "Apartment" (Land Use Code 220) rates were used for all the proposed multi- family residential units, which have a slightly higher rate than "Condominium/Townhouse" (Land Use Code 230) to account for a worst -case condition. 3. Summary of Trip Generation Results Table 2 presents the net increase in vehicle trips associated with redevelopment of the site. Some of the retail trips come from traffic already using roadways adjacent to the site, and some may divert from roadways further away. Table 3 summarizes the estimated number of pass -by, diverted, and primary trips for the project. The proposed redevelopment is expected to generate about 3,660 vehicle trips per day and about 332 vehicle trips during the PM peak hour. Of the PM peak hour trips, 238 would be primary trips that are new to the site area. Further information related to the assumed trip types are presented later in Section 4 below. heffron -2- June 26. 2009 Edmonds Shopping Center Redevelopment Project Preliminary Trip Generation Analysis TahIR 2_ Proposed Vehicle Trips — by Land Use trans r3 o r t a t i o n, Daily Vehicle AM Peak Hour Vehicle Trips PM Peak Hour Vehicle Trips In Out Total In Out Total Land Use Size Trips Retail 20.202 sf 710 10 6 16 30 31 61 Restaurant 10,100 sf 1,030 49 45 94 54 37 91 Residential 360 units 1920 1 25 125 150 1 120 60 180 Total 3,660 1 84 176 260 1 204 128 332 Source: Heffron Transportation, Inc. June 25, 2009. Table 3. Proposed Vehicle Trips - by Trip Type Trip Type Daily Vehicle Trips AM Peak Hour Vehicle Trips PM Peak Hour Vehicle Trips in Out Total In Out Total Primary Trips Diverted -Linked Trips Pass -by Trips 2,580 390 690 49 12 23 84 141 12 23 176 190 24 46 260 157 17 30 204 81 17 30 128 238 34 60 332 Total 3,660 Source: Heffron Transportation, Inc. June 25, 2009. Table 4 shows the existing trip generation by trip type. The difference between the two developments is the net increase in trips related to the proposed redevelopment. The redeveloped site would increase the vehicle trips at the site driveways by 1,680 daily trips, 214 AM peak hour, and 160 PM peak hour trips. Table 4. Vehicle Trips by Trip Type — Existing Retail Mall Daily Vehicle AM Peak Hour Vehicle Trips PM Peak Hour Vehicle Trips In Out Total In Out Total Trip Type Trips Primary Trips 790 14 4 18 32 36 68 Diverted -Linked Trips 510 6 6 12 23 23 46 Pass -by Trips 680 8 28 8 18 16 46 29 84 29 88 58 172 Total 1,980 Net Change to Proposed +1,680 +56 +158 +214 +120 +40 +160 Source: Heffron Transportation, Inc. June 25, 2009. heffron - 3 - June 26. 2009 Edmonds Shopping Center Redevelopment Project he f f r on Preliminary Trip Generation Analysis transportation, 4. Detailed Trip Generation Assumptions and Calculations This section presents detailed information related to the assumptions and methodology used to determine the site's trip generation. It defines and explains how the number of person trips was calculated, and then describes the modes of travel for those trips including vehicle trips, transit trips and pedestrian/bicycle trips (non -vehicle trips). The following subsections detail the trip rates used in the analysis, internal trips expected to be made between uses on the site, mode of travel, and retail trip characteristics. Person Trips Trip generation for new projects is typically determined using rates and equations in Trip Generation (Institute of Transportation Engineers [ITE], 8th Edition, 2008). This reference manual summarizes the results of numerous traffic studies throughout the country for a variety of land -use types. The applicable rates and equations in ITE's Trip Generation are based on studies of stand-alone suburban land uses. As a result, trip generation rates for residential and retail uses reflect the suburban trend of driving in single -occupant vehicles (SOVs). However, the Edmonds Shopping Center site is not an isolated suburban site —it is located near downtown Edmonds with some residents who live within walking distance of the site. It is also located within walking distance of the Edmonds Ferry Terminal, and the Sound Transit Commuter Rail Station. As recommended by ITE in Trip Generation, the ITE trip generation rates were adjusted to account for these other travel modes. The ITE trip generation rates and equations were used as the basis for determining the number of per- son trips for all uses. Person trips are the total number of trips made by all modes of travel, including carpooling, transit, walking and bicycling. The person trips were determined by applying an average vehicle occupancy (AVO) factor to the ITE vehicle trips for each land use. The assumed AVO factors and mode of travel percentages for each land use are summarized in Table S. Table 5. Mode Split and Average Vehicle Occupancy (AVO) Assumption Residential Land Use Retail Restaurant Assumed AVO Rate Applied to ITE Rates 1.09 a 1.20 b 1.52 c AVO Rate for Site Area in Edmonds 1,098 1.20 b 1.52 c Non -vehicle Trips d 10°% 10°% 10°% Person Trips by Vehicle 90°% 90°% 90°% Source., Heffron Transportation, Ina, June 1, 2009. a. Estimated AVO rate (personslvehicle) since none are listed for residenlial uses, based on 'Journey to Work' Census 2000 data for Transportation Analysis Zone (TAZ) 578, which encompasses the site. b. AVO rates are not published for these uses; estimated by Heffron Transportation and assumed to remain unchanged in site area c. AVO role from ITE's Trip Generation for Restaurant, assumed the some as AVO rate in Edmonds. d. Non -vehicle trips (transil, train, walking/bicycling) based on Journey--to-Work surveys for residential uses. heffron - 4 - June 26, 2009 Edmonds Shopping Center Redevelopment Project heffron Preliminary Trip Generation Analysis Internal Trips The total number of trips generated by a mixed -use site includes "internal trips," or trips made between one use on the site and another use on the site. For example, a trip that a resident makes to the retail space is included in the trip generation values for both the residential unit and the retail space. All of the internal trips at this site are expected to be made by foot, and would not create vehicle trips. Chapter 7 of the Trip Generation Handbook is devoted to estimating trip generation for multi -use developments, and includes a methodology to estimate the number of internal trips that can be expected at specific types of sites. This method is based on the type and size of various land uses. The more balanced the mix of uses, the higher the percentage of internal trips. Developments with a predominance of one type of use (e.g., mostly retail or mostly residential) typically have a lower percentage of internal trips. ITE's methodology to determine internal trips includes several steps: 1. Determine the number of trips expected to be generated by each land use as if each was on a separate site. 2. Determine the number of internal trips based on internal capture rates presented in the Trip Generation Handbook. 3. Balance the number of internal trips to and from all land uses at the site. 4. Total the resulting number of internal trips and calculate the percentage of internal trips. Using the methodology described above, the internal capture rates for the various alternatives were estimated and are shown in Table 6. Table 6. Internal Capture Summary — Trips between Proposed Site Uses % of Intemal Trips for Each Land Use Land Use Daily AM Peak Hour PM Peak Hour Retail 10°% 10% 10% Restaurant 10°% 10°% 10°% Residential 11% 10% 11% Source: Heffron Trenspottatlon, Inc., June 25, 2009. Rates were derived from methodology in the Tdg Generation Handbook (1TE, June 2004). Mode of Travel The site is located adjacent to Sound Transit's Edmonds Commuter Rail Station and Washington State Ferry Terminal. It is also located within walking distance to downtown Edmonds and the residential population there. Because of its location, some of the trips are expected to be made by non -automobile modes of travel (transit, train, bicycle, or walking). For this site vicinity, Puget Sound Regional Council (PSRC) provided data showing non -automobile rates of 10% based on year 2000 Census surveys. It is expected that this rate is conservatively low given that it is almost a decade old (newer data are not available), and were taken before the Sound Transit station was built. The remaining 90% of the trips were assumed to be made by single -occupant vehicles or carpools. The mode -of -travel assumptions for each land use were previously presented in Table 5. heffron - 5 - June 26. 2009 Edmonds Shopping Center Redevelopment Project Preliminary Trip Generation Analysis Retail Trip Characteristics • , trans ortat�on, inc. Retail trips are different than other types of trips that the site would generate. Unlike residential trips, retail developments attract a portion of their trips from traffic that is already using streets in the site vicinity. Retail trips are typically divided into three trip types —pass -by trips, diverted -linked trips, and primary trips —which are described further below. • Pass -by trips are trips that are already on a roadway immediately adjacent to the site en route to another destination. For example, people driving along Sunset Avenue S could stop and shop or dine at the site. This would be a pass -by trip. Pass -by trips do not require a diversion from another roadway. • Diverted -linked trips are trips that are attracted from the traffic on roadways within the vicinity of the site, but that require a diversion from that roadway to another roadway to gain access to the site. For this site, a diverted -linked trip could be one that comes from Main Street. These trips would divert to local roadways to access the site. • New (primary) trips are single -purpose trips generated by retail or a restaurant. New trips are generally assumed to begin and end at home, although some new trips could originate at work or other locations. The percentage of driveway trips that is attributed to each of the above components depends on the size, type, and location of a proposed project. Information in the Trip Generation Handbook was used to derive the percentages for this site. The trip type assumptions are presented in Table 7. Table 7. Assumed Trip Characteristics % of Trips for Each Land Use Land Use Pdmary Trips Pass -by Trips Diverted -Linked Trips Retail 40% 34% 26°% Restaurant 37% 43% 20°% Residential 100% 0°% 0°% Source: Hebron Transportation, Inc., June 25, 2009. Rates were derived tram information in the Trip Generation Handbook (ITE, June 2004). MMB/mch heffron - 6 - June 26.2009