Transportation & Traffic Engineering

Transcription

1 Transportation & Traffic Engineering 1) Project Description This report presents a summary of findings for a Traffic Impact Analysis (TIA) performed by A+ Engineering, Inc. for the Hill Country Family Fitness Center Project located north of US Hwy 281 and Hwy 46 in Spring Branch, Texas as shown in Figure 1. Figure 1: Site Location The Hill Country Family Fitness Center Project consists of a 52,500 square-feet (SF) building that will serve as a fitness club for the Rodeo Subdivision and adjacent neighborhoods of the area. The project is anticipated to be completed by the end of ) TIA Introduction The Transportation Engineering team has provided all analysis required by the City of San Antonio and/or by Comal County. The analysis and design calculations and procedures have conformed with the following codes and entities: City of San Antonio Unified Development Code (due to lack of a detailed provision by Comal County), Institute of Transportation Engineers Trip Generation Manual, 8th Edition, TxDOT s Roadway Design Manua,l and Transportation Research Boards Highway Capacity Manual, Note that even though the proposed development is located in Spring Branch, Texas, due to the absence of a detailed code by Comal County, the COSA UDC was adopted for this project. Based on Article V, Section of the COSA UDC, the amount of peak hour trips (PHT) generated by this proposed development (see Section 2.1 for details) requires a traffic impact analysis (TIA) Level I. Therefore, A+ Engineering Design was retained to prepare a Level I Traffic Impact Analysis (TIA) for the Hill Country Family Health Fitness Center. A meeting was conducted with city public works and development services staff on October 24 th, 2013 to determine the requirements and scope of the TIA in accordance with generally accepted practice. The meeting determined the type of study, study area, trip generation, trip distribution and assignment, time period of analysis, and established growth rate.

2 This study assesses the transportation impacts of the proposed development on the thoroughfare to review site access and circulation as required by Sections and of the Code of Ordinances for the City of San Antonio. The following sections provide a detailed report of the analyses performed by A+ Engineering Design. 3) Trip Generation The first step was to estimate the traffic generated by the new development proposed. The generated traffic was determined using the ITE Trip Generation, 9 th Edition by the Institute of Transportation Engineers. This manual was used to estimate the number of trips ends that may be generated by the construction project. The number of trips generated by the development is a function of the type and quantity of the land use of the development. The proposed development is categorized as Land Use 492 (Health/Fitness Club) in the ITE Trip Generation, 9 th Edition. This land use is for privately owned facilities that primarily focus on individual fitness or training. Typically they provide exercise classes, weightlifting, fitness and gymnastics equipment; spas; lockers rooms; and small restaurants or snack bars. This land use may also include ancillary facilities, such as swimming pools, whirlpools, saunas, tennis, racquetball and handball courts and limited retail. These facilities are membership clubs that may allow access to the general public for a fee. The gross floor area was selected as the independent variable, which is a measurable and predictable unit describing the study site that can be used to predict the value of the dependent variable (trip ends). The gross floor area of a building is defined as the sum (in square feet) or the area of each floor level that are within the principal outside faces of exterior walls. The proposed development has a total gross floor area of 52,500 square feet. The average rate of generated traffic for a Health/Fitness club during a weekday AM peak hour is 1.41 trips per 1000 square feet of gross floor area with a 1.5 standard deviation. Following the ITE Trip Generation recommendation of using the average rate if the standard deviation is no more than 10% greater than the average rate: % we were able to calculate the generated traffic during the AM peak hour. The results are summarized in Table 1. The average rate of generated traffic during a weekday PM peak hour is 4.06 trips per 1000 square feet of gross floor area with a 2.02 standard deviation. Following the ITE Trip Generation recommendation of using the average rate if the standard deviation is no more than 10% greater than the average rate: % we were able to calculate the generated traffic during the PM peak hour. The results are summarized in Table 1.

3 Gross Floor Area (1000 sq.ft.) 52.5 Weekday Generator AM Peak Weekday Generator PM Peak Trips / Unit % Enter / % Exit 42% 58% 68% 32% Total Trips Enter / Exit Table 1: Traffic Generation As shown on Table 1, the maximum PHT that the proposed development will generate, the Weekday Generator PM Peak, equals to 213 trips. According to the threshold by the City of San Antonio, 76 PHT, a traffic impact analysis is required, which will be discussed bellow. 4) Trip Distribution and Traffic Assignment The traffic generated was added to the road network based on the percentages of traffic on each road obtained from the existing traffic demand (Task 1.1). The PHT from Task 1.1 were distributed to subsequent intersections until the minimum of seventy-six (76) PHT or a one and one-half (1.5) mile maximum distance was reached. For this case, the PM PHT were used since they showed a greater number of traffic generated and therefore are critical in the analysis. A map summarizing the trip distribution for inbound and outbound PHT is shown in Figure 2 and Figure 3. These figures show the PHT to be distributed along with the percentages of distributing and the identified intersections to be analyzed. Figure 2: Trip Distribution Network Diagram Outbound Figure 3: Trip Distribution Network Diagram - Inbound

4 The trip distribution analysis showed that the intersections that may be affected by the new development are as follows (shown on Figure 1 & 2): Rodeo Drive and U.S. Highway 281, Rodeo Drive and Texas Oaks, and Rodeo Drive and River Way. And after a site visit on September 7,2013 the following information was gathered: o Rodeo Drive: Number of lanes: 1 eastbound / 1 westbound Speed Limit: 30 mph o US Highway 281 Number of lanes: 2 northbound / 2 southbound with 50 feet median Speed Limit: 60 mph o Texas Oaks Number of lanes: 1 eastbound / 1 westbound Speed Limit: 30 mph 1 deceleration lane on US Hwy 281 to enter Rodeo Drive (350 ft.) o River Way Number of lanes: 1 eastbound / 1 westbound Speed Limit: 30 mph o Traffic Signs Stop sign at Rodeo Drive to enter US Hwy way stop sign in Rodeo Drive and Texas Oaks intersection Stop sign at Rodeo Drive to enter River Way 5) Traffic Flow Analysis This task consisted in a traffic flow analysis on Rodeo Drive and all adjacent streets and intersections that were identified in the previous section. This traffic flow analysis helped determine the existing conditions of the site and its vicinity and the existing traffic demand. The analysis provided us with the following information: peak hour factor (PHF), trip distribution percentages, number of peak hour trips (PHT), and percent trucks. Traffic counts were gathered for the three identified critical intersections from Section 1.2. The traffic data was gathered for the AM (7:00 9:00) and PM (4:00 6:00) peak hours. The right-turn, left-turn, and thru traffic for all directions (north, south, east, and west) were counted. These counts were then used to calculate the peak hour, peak hour factor, percentage of trucks, peak hour turning movements, and peak hour turning percentages. The spreadsheets including all the information and results for the AM and PM counts for all three intersections are provided at the end of the report. These counts

5 were then used to perform the capacity analyses using Synchro, which is describe in the next section. 6) Traffic Impact Analysis (TIA): The purpose of this analysis is to identify travel responses in routing, scheduling, and traffic flow due to the new construction project. This is accomplished by combining the existing traffic volumes plus the forecasted conditions that will develop. The forecast of future traffic flow and impact will reflect the traffic conditions once the new construction has been finalized and the health center is fully operational. With all information about the intersections that was gathered in Section 1, the intersections were analyzed using Synchro8 traffic analysis software. The Synchro analysis provided the existing LOS (level of service) of each intersection. For this project, only the PM hour was analyzed due to the fact that both the existing volumes and the generated traffic volumes were both greater for the PM peak hour and therefore making that hour more critical than the AM peak hour. a. Existing Conditions Based on the peak hour volumes computed from the traffic counts of the three identified critical intersections, a Synchro model was created. This model contained all the information gathered such as the geometry, traffic volumes information. A visual model of the input information is summarized in Figure 3. Figure 4: Volume Summary of Existing Conditions The Synchro report for this model is provided at the end of this report. The Synchro report showed a level of service (LOS) of A for all three intersections analyzed. These levels of service will be used as a benchmark to compare the forecasted conditions. b. Forecasted Conditions For the forecasted conditions, a model with the generated traffic plus the expected traffic growth was analyzed. Using the compound formula, 1, where G represents the growth rate and n represents the number of years, a projection 5 year future volume of traffic was calculated. The growth rate was conservatively chosen as 5% growth per year. With these numbers a Build

6 plus 5 years scenario was analyzed. The analysis included the 5-year projection and the development generated traffic. Figure 4 shows a summary of the generated traffic volumes and Figure 5 shows a summary of the generated traffic plus the existing conditions after a five-year projection. Figure 5: Volume Summary of the Generated Traffic Figure 6: Volume Summary of the 5 Year Projection The Synchro report for this model is provided at the end of this report. The Synchro report showed a level of service (LOS) of A for all intersections analyzed. 7) Conclusion The Transportation Engineering team has used the TIA results to determine if any changes to the existing roadway are needed. The forecasted LOS was compared with the previous existing LOS. Since the LOS does not change, no modifications nor any permission to modify the public roadway are needed.