Statewide Access Management Coordination GoToWebinar

Transcription

1 Statewide Access Management Coordination GoToWebinar Promoting innovative, efficient, and exceptional work since 1988 April 26, 2017 ( 2:30 EST, 1:30 CST) Answers to Common Questions Yes we will provide a handout of the slides Yes we will record this session and it should be available in a few days 1

2 Agenda Introductions Amie Longstreet and Gary Sokolow Safety Analysis of Driveway Characteristics Along Major Urban Arterial Corridors in South Carolina. Wayne Sarasua Clemson University Buc ee s Time permitting Your Friendly Webinar Team Our Special Guest Wayne Sarasua, Ph.D., P.E. Clemson University 2

3 Regular Statewide Access Management Coordination Webinar Usually the 4th 2:30 pm to 3:30pm (Eastern Time) For FDOT staff (and their consultants) to discuss questions on Access Management Site Impact Trip Generation Poll Who do you represent? 3

4 SAFETY ANALYSIS OF DRIVEWAY CHARACTERISTICS IN SOUTH CAROLINA USING GIS Wayne A. Sarasua, Ph.D., P.E. Glenn Department of Civil Engineering Clemson University Overall Goal The overall goal of this project is to enhance SCDOT s current access management practices resulting in a reduction in crashes, injuries, and fatalities on South Carolina roadways as well as improved traffic flow 4

5 Literature Review Access Management studies generally fall into three categories : Impacts on Safety Median Access point density Sight distance Intersection & Interchange Turn prohibition Impacts on Traffic Operations Level of service Capacity Impacts on Residents and Business Literature Review Access point density: Schultz et al., Safety impacts of access management techniques in Utah, (2007) evaluated the safety performance of arterials in which access management techniques have been implemented. They concluded that the relationship between access points per mile and crash rate has a positive correlation in Utah. Frawley and Eisele, Crash analyses of raised medians and driveway density: How access management makes communities safer, (2004) completed an evaluation of 11 case studies in Texas and Oklahoma and showed that implementing raised medians and performing driveway consolidation would reduce the potential number of conflicts points along roadways. Conclusion: reducing access point density reduces crash rates, reduces speed differential between vehicles, enhances operation and could improve roadway capacity and reduce need of new capacity improvement 5

6 Literature Review Medians: Gattis et al., Roadway median treatments, (2010) examined relationships among crash rates and different types of median (None with occasional left turn lanes, two way left turn lane, Raised, Depressed) of roadways in Arkansas. They concluded that raised or depressed median yield the lowest crash rates. Mauga and Kaseko (2010) evaluated and quantified the impact of types of medians, including raised medians and two way left turn lanes on traffic safety in the midblock sections. The results showed that segments with a raised median had lowered the crash rate by 23% compared to segments with a TWLTL. Schultz et al., Safety benefits of median installations in Utah, (2012) analyzed safety at locations where raised medians are installed. They concluded that raised medians significantly reduce crash frequency and severity. Frawley, Raised median economic impact and safety research findings: Application for Cooper street, (2010) studied the benefit of converting a two way left turn lane to a raised median for particular locations in Bryan, Temple and Tyler, Texas. The benefits include lower crash frequency, fewer crashes involving leftturns, no migration of crashes to intersections, very few U turn crashes, and fewer severe crashes. Conclusion: Raised medians reduce crash frequency and severity with no migration of crashes to intersections. Traffic operations are improved. A Methodology for Determining the Economic Impacts of Raised Medians William L. Eisele, P.E., and William E. Frawley, AICP (TTI 1999) Business owners who were present before, during, and after the median installation felt that their regular customers continued to use their businesses In contrast, those businesses that were interviewed prior to the installation of the raised median thought their customers would be less likely to continue to use their businesses Perceptions appear worse than reality 6

7 Data Collection Procedures and Data Summary 30 Preliminary Corridors 7

8 SC Geocoded Crashes Problems with hand-held GPS data 1. Several crash records were missing either longitude or latitude or both 2. Some crash records were in state plane coordinates, not latitude and longitude 3. Several crash records were in Decimal Degrees (DD), not DMS 4. Some crash records had their longitude and latitude values swapped 5. Most of the latitude values did not include a negative sign 6. Several coordinates were recorded with insufficient precision by one or two decimal places 7. Some crash records had spaces and letters as part of the coordinate entry 8. Some coordinates included additional zeroes to make up for the insufficient precision 9. Some crash records had erroneous coordinate values 8

9 Percent of Crash Data by Geocoded Category and by Year Rear-end and angle crashes on US 25 in Greenville, SC for 2010 (left) and 2012 (right) 9

10 SC 9 Spartanburg (2010 Blue Star VS 2014 Orange Circle) US 17 Berkeley (2010 Blue Star VS 2014 Orange Circle) 10

11 Symbol Table Driveway Related Crash Angle Crash Rear end Crash Greenville US 25 Length 66 Driveway Crashes 309 Rank 2 Rear End 880 Angle 693 Clusters 9 11

12 Greenville US 25 Greenville SC 146 Length 13.9 Driveway Crashes 294 Rank 3 Rear End 676 Angle 373 Clusters 20 12

13 Greenville SC 146 Greenville SC

14 Greenwood US 25 Richland US 1 Length 22.0 Driveway Crashes 353 Rank 1 Rear End 1270 Angle 715 Clusters 30 14

15 Richland US 1 15

16 Before and After Results 16

17 Richland US 176 Final 11 Corridors COUNTY ROUTE TYPE ROUTE NUMBER LENGTH (MILES) 3 YEAR DRIVEWAY AVG RANK DRIVEWAY CRASHES Richland US Greenville US Greenville SC Richland US Lexington US Horry US Spartanburg SC Greenville US York US Berkeley US Florence US

18 Map of 11 Corridors Corridor Analysis Data Collection Process Geometric Data were collected for selected corridors in three categories Segment intersection to intersection Driveway Intersection All data were geocoded into ArcGIS 18

19 Sample Driveway with Attributes Driveway Spacing 19

20 Skew Angles Safety Analysis 20

21 Right In Right Out Buffers Full Access Buffers 21

22 Proximity Analysis Average Distance from Reported Route by Year Average Distance (FT) Route US 1, Richland US 25, Greenville SC 146, Greenville US 176, Richland US 1, Lexington Buffers with Crash Overlay 22

23 Annual Crash Frequency by Driveway Class Annual Crash Frequency Full Access vs Right-in, Right-out 23

24 Negative Binomial Estimation Results for Crashes per Driveway Negative Binomial Estimation Results for Crashes per Driveway 24

25 Crash Modification Factors Crash Modification Functions 25

26 Crash Modification Functions Driveway Width CMF DW DW a -DW b Crash Modification Function 26

27 Crash Modification Function Safety Performance Function 27

28 Crash Modifications Function Corner Crash Analysis 28

29 Corner Clearance Annual crash frequency 0 to 150 feet from an intersection vs crash frequency 150 feet to 300 feet Distance from Intersection US 1 Richland US 25 Greenville SC 146 Greenville US 176 Richland SC 9 Spartanburg US 17 Berkeley # of driveways HP 2012 Crashes Crash frequency 0-150ft ft 0-150ft ft 0-150ft ft Other Project Components Waiver Analysis Operational Analysis Economic and Benefit Cost Analysis 29

30 Recommendations for SCDOT ARMS Sample Specific Changes to ARMS 30

31 Findings & Conclusions Problems result when developers circumvent standard adherence through the waiver process Comprehensive driveway database critical to analysis Precise crash data is critical to analysis Makes it possible to associate crashes with driveways Can also facilitate corridor level and even statewide analysis with more robust results Reading crash narratives is time consuming and it is sometimes difficult to associate a crash with a particular driveway Use junction type with caution. Many driveway related crashes may be overlooked. 31

32 Research Golden Nuggets for Practical Application Research Findings: Raised medians can cut driveway related crashes in half (CMF of 0.49). Right in, right out driveways eliminate 3 conflict points that are the most critical with respect to crash severity and RIRO driveways have less than half the crash frequency of full access driveways. Reducing access point density improves roadway capacity and reduces need for new capacity improvements. Driveways within 150 of a an intersection have nearly twice the crash frequency of driveways 150 to 300 from an intersection. Research Golden Nuggets for Practical Application (cont.) Better access policies result in lower crash severity, not just frequency. Approval of access waivers from adherence to good design practice often result in higher crash frequency. High turnover land use such as fast food restaurants have much higher crash frequency over other land uses such as small businesses. 32

33 Thank you! Questions? Updates of Interest 33

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36 Buc-ee s Gas and Convenience Stores Markets over 50,000 sq. ft Fueling Positions over 100 Buc-ee s - over 100 Fueling Positions 36

37 Buc-ee s Buc-ee s 37

38 What Help do You Need? 38

39 USB Library Questions & Comments 39

40 Poll slide Poll slide 40