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HomeMy WebLinkAboutSD-22-03 - Supplemental - 1170 1180 Dorset Street (15) Lamoureux & Dickinson Page 1 Consulting Engineers, Inc. Wheeler Parcel & Park Road Commons Residential Developments Traffic Impact Assessment Park Road South Burlington, VT November 13, 2020 rev. January 24, 2022 Project Introduction This updated TIA examines the cumulative traffic impacts of two proposed developments: C A 32-unit residential development located in the southwest corner of the Wheeler Parcel (northeast corner of the intersection of Dorset St and Park Rd. Access will be via a looped roadway accessing onto Park Road. The proposed residential units will include 10 single-family units and 22 duplex units. C A 14-unit residential development (Park Road Commons) located in the southeast corner of the intersection of Dorset St and Park Rd. Access will be via two cul-de-sacs accessing onto Park Rd. The westerly cul-de-sac will line up directly across the Wheeler Parcel’s westerly access. The easterly cul- de-sac will be located to the east, between the Wheeler Parcel’s looped roadway. Both developments also include new sidewalks and shared use path connections linking with existing nearby shared use paths. Additionally, the trip generation of both developments has been updated using the 11th Edition of ITE’s Trip Generation. For purposes of this traffic impact assessment (TIA), it is anticipated that construction of both developments will commence in 2022. The following sections present the results of our analyses of traffic congestion and safety conditions in the immediate vicinity of the two developments. Background Traffic Volumes Background traffic volumes at the Dorset Street / Park Road intersection were obtained from a pm peak period turning movement count performed by this office at the Dorset Street/Park Road intersection on Thursday, November 5, 2020. A copy of the count results is attached in Appendix A. The observed peak hour volumes from the above turning movement count require two adjustments. The first is the usual DHV adjustment. For this, we used hourly data from VTrans Continuous Count Station (CTC) D277 located on Shelburne Road just north of Shelburne village. Comparing the afternoon peak hour volume on the first Thursday in November 2019 to the design hour volume (DHV) for 2019 yielded a DHV adjustment factor of +14% (1.14). The second adjustment is to account for the effect of the COVID pandemic on traffic volumes. As this report is being written, the available data from CTC D277 extends to mid-October. Comparing the Lamoureux & Dickinson Page 2 Consulting Engineers, Inc. afternoon peak hour volume on Thursday, October 15, 2020 to the same volume on Thursday, October 17, 2019 yielded a second adjustment factor of +7% (1.07). Combining those two adjustment factors yields an overall DHV adjustment factor of +22% (1.22). Background traffic growth rates were obtained from VTrans’ Red Book.1 VTrans’ most recent estimates of traffic growth on Vermont’s highways predict a 0.5% growth rate from 2020 to 2022 and a 3% growth rate from 2020 to 2027. For the purposes of this updated TIA, the previous growth rates of 1% and 3%, respectively, have been retained. With am peak hour volumes being less than pm peak hour volumes at both intersections, this traffic impact assessment (TIA) only examines traffic congestion conditions during the latter time period. Figure 1 presents the estimated 2022 and 2027 background (no-build) design hour turning movement volumes in the vicinity of the two developments. Figure 1 - No-Build DHV’s 2022 2027 Dorset St Dorset St 437 39 446 40      30 Park Rd  30 Park Rd  2  3     293 4 299 4 Dorset St Dorset St Project-Generated Trips Anticipated peak hour trips for each development were calculated using trip generation rates2 for single family dwellings (ITE Land Use Categories #210 and 215). Table 1 summarizes the resulting peak hour trip generation estimates. Table 1 - Weekday Trip Generation Development Average Weekday (vte/day) AM Peak Hour (vte/hr) PM Peak Hour (vte/hr) Enter Exit Total Enter Exit Total Wheeler Parcel 10 single-family detached 22 single-family attached 121 158 279 2 3 5 7 8 15 9 11 20 7 7 14 4 6 10 11 13 24 Park Road Commons 14 single-family attached 101 2 5 7 5 3 8 1 Continuous Traffic Counter Report Based on 2020 Traffic Data, Vermont Agency of Transportation, May 2021 2 Trip Generation, Institute of Transportation Engineers, 11th Edition Lamoureux & Dickinson Page 3 Consulting Engineers, Inc. The directional distributions of the above pm peak hour development-generated trips are estimated to be 85% to/from the north and 15% to/from the south. This is based on pm peak hour directional patterns observed entering and exiting the east approach of Swift St at its intersection with Dorset St during a June 2016 turning movement count performed by VTrans. Figure 2 presents the estimated pm peak hour trip directional distributions for both developments (combined). Figure 2 - Estimated Development PM Peak Hour Trips Dorset St 0 16    11 Park Rd  2   0 3 Dorset St Combining the development-generated trips with the no-build volumes provides the 2022 and 2027 Build DHV turning movements shown in Figure 3. Figure 3 - Build DHV’s 2022 2027 Dorset St Dorset St 437 55 446 56      41 Park Rd  41 Park Rd  4  5     293 7 299 7 Dorset St Dorset St Traffic Congestion Levels of service (LOS) at intersections are determined by the average control delay; measured in seconds per vehicle. The methodology for analyzing LOS is established by the Highway Capacity Manual (HCM)3. Table 2 summarizes the LOS/delay criteria for unsignalized intersections. Table 2 - Unsignalized Intersection Level of Service/Delay Criteria LOS Avg. Delay (sec/veh) LOS Avg. Delay (sec/veh) A B C ≤10 ≤15 ≤25 D E F ≤35 ≤50 >50 3 Highway Capacity Manual, Transportation Research Board, 6th Edition Lamoureux & Dickinson Page 4 Consulting Engineers, Inc. In Vermont, LOS C represents the desired design standard for roadways and signalized intersections.4 At two-way stop controlled (unsignalized) intersections having greater than 100 vph approach volume on a single-lane side street approach or greater than 150 vph approach volume on a two-lane side street approach, the VTrans level of service policy establishes LOS D as the desired design standard on the minor street approach(s). There is no level of service standard for unsignalized intersections not meeting the above side street volume thresholds. Reduced levels of service are acceptable in densely settled areas where volume/capacity ratios remain below 1.0 and/or the improvements required to achieve LOS C would create adverse environmental and cultural impacts. Transportation demand management (TDM) strategies can also be used to help mitigate levels of service not meeting the foregoing standards. While the Dorset St/Park Rd intersection does not meet the above approach volume thresholds for unsignalized intersections, intersection capacity analyses were nonetheless performed for the purpose of this TIA. All analyses were performed using Highway Capacity Software v.2010. The impact on future levels of service and average delays which will result from both developments was analyzed by performing both no-build and build analyses, and comparing the results of the two. All analyses were performed using existing geometric conditions. The results are presented in Table 3. Detailed analysis worksheets are also attached in Appendix B. Table 3 - Dorset St / Park Rd Levels of Service Approach & Lane Group No-Build Build LOS Delay V/C LOS Delay V/C 2022 DHV Park Rd WB LT-RT Dorset St SB LT B A 10.4 7.9 0.05 0.03 B A 10.8 8.0 0.07 0.04 2027 DHV Park Rd WB LT-RT Dorset St SB LT B A 10.7 7.9 0.05 0.03 B A 11.0 8.0 0.07 0.04 The above results indicate that the Dorset St / Park Rd intersection will continue to experience low delays and good levels of service with these two developments. Safety The posted speed limits on Dorset St and Park Rd in the vicinity of both developments are 40 mph and 25 mph, respectively. Both streets provide one travel lane in each direction and have parallel shared-use paths for use by pedestrians and bicyclists. Existing traffic patterns entering and exiting Park Rd are overwhelmingly directional to and from the north due to Park Rd being a loop street also connecting with Dorset St to the south via Old Cross Rd. A southbound left-turn lane presently exists on Dorset St serving the left-turn movement onto Park Rd. This exclusive left-turn lane reduces conflicts between southbound left-turns and through movements, thereby improving safety conditions for southbound traffic on Dorset St. 4 Vermont Agency of Transportation Highway Design “Level of Service” Policy, May 31, 2007 Lamoureux & Dickinson Page 5 Consulting Engineers, Inc. Both new intersections of the Wheeler Parcel’s new roadway onto Park Rd will have intersection sight distances exceeding the recommended 280 ft for the 25 mph posted speed limit. This sight distance also provides the recommended safe stopping sight distance for vehicles exceeding the speed limit by as much as 10 mph.5 Park Road Commons’ roadways will also have greater than 280 ft of sight distances. VTrans identifies high crash intersections and high crash segments on major highways and urban streets based on their five-year crash history. The most recent high crash report6 identifies the Dorset St/Kennedy Dr/I-189 intersection, located 1 mile north of the two developments, as a high crash location. This intersection experienced 40 crashes over the 2012-2016 five-year period. Of those, 39 were property damage only crashes. There was one injury resulting in the remaining crash. During the 2014-2018 five- year period, the number of crashes dropped to 38; all of them being property damage only crashes. The large majority of the above crashes are same direction rear-end and sideswipe crashes. There are not any obvious geometric deficiencies at this intersection or on its approaches. It also operates under traffic signal control using split (exclusive) signal phases for each of its approaches; thus minimizing vehicular conflicts. Crosswalks, pedestrian signals and street lighting also exist. Multi-Modal Facilities Both developments will be served by existing shared-use paths extending north and south on the east side of Dorset St and to the east on the north side of Park Rd. Wheeler Parcel - In the Wheeler Parcel development, a new sidewalk will be constructed paralleling the new roadway. A new cross-country shared-use path connection will also be constructed from the approximate northerly apex of that roadway to the existing shared-use path on the east side of Dorset St. Park Road Commons - This development will construct new sidewalks along Private Road “B” and along the south side of Park Road between Private Roads “A” and “B” together with a new crosswalk on Park Rd to link with the existing shared-use path on its north side. It will also construct a new walking path from the cul-de-sac of Private Road “A” to the existing shared-use path on the east side of Dorset St. The closest local transit service is Green Mountain Transit’s Purple Line serving Dorset St from Kennedy Drive north. Transportation Impact Fees Both developments will be responsible for paying both local and state transportation impact fees. The estimated impact fees for each are outlined below: At the City level, the Road Improvement Impact Fee is set at $924 per pm peak hour trip end for single family dwellings constructed in 2021. The Road Improvement Impact Fee is used to pay costs associated with the following local road improvement projects: C Hinesburg Road/Van Sicklen Road Intersection Improvements 5 The safe stopping sight distance for a vehicle traveling at 35 mph on a flat grade is 250 ft. That increases to 275 ft on a 6% downgrade. 6 2012-2016 High Crash Location Report, Vermont Agency of Transportation, August 2017 Lamoureux & Dickinson Page 6 Consulting Engineers, Inc. C Williston Road Reconstruction C Airport Drive Extension C Airport Parkway/Ethan Allen Road Intersection Improvements C Tilley to Community Drive Connector C City Center Road Network The cost of this impact fee for each development is estimated to be: C Wheeler Parcel: $22,176 C Park Road Commons: $7,392 The City also assesses a Recreation Impact Fee of $1,665 per unit, the majority of which is designated for constructing recreation paths and bicycle lanes. The cost of this impact fee for each development is estimated to be: C Wheeler Parcel: $53,280 C Park Road Commons: $23,310 At the State level, both developments will also be assessed an Act 145 Transportation Impact Fee. The only state highway improvement project located within a 3-mile travel distance is the Champlain Parkway in Burlington. The Champlain Parkway has an impact fee of $2,069 per pm peak hour vehicle trip end. Both developments are eligible for a 15% adjustment in that impact fee due to their new sidewalk and shared- use path connections, reducing the impact fee to $1,759 per pm peak hour vehicle trip end. The cost of this impact fee for each development is estimated to be: C Wheeler Parcel: $3,518 C Park Road Commons: $1,759 Calculations of the development-generated trips using the Champlain Parkway are enclosed as Appendix C. Conclusions From the foregoing analyses, we have formed the following conclusions regarding the potential traffic congestion and safety impacts of these two developments: C Intersection capacity analyses at the Dorset St/Park Rd intersection indicate that acceptable levels of service will be maintained with both developments. C The relatively small volume of additional traffic resulting from both will not create unsafe traffic conditions. C Payment of state and local transportation-related impact fees will mitigate their impact on future off- site traffic conditions on the adjacent highway network.