Placer County Traffic Accident Analysis System (TAAS) by Fehr & Peers

Placer County

Traffic Accident Analysis System (TAAS) Version 1 (2009)

Prepared by:

Fehr & Peers Under direction of Placer County Department of Public Works, Transportation Division August 2009

TABLE OF CONTENTS

A. Introduction........................................................................................................................................................ 1 Scope of the TAAS and This Handbook.............................................................................................................. 2 Historical collision Statistics................................................................................................................................. 2 B. Program Modules & Collision Data.................................................................................................................. 6 Traffic Collision Reports ...................................................................................................................................... 6 Statewide Integrated Traffic Records System ..................................................................................................... 6 Crossroads Software ........................................................................................................................................... 6 Geographic Information System .......................................................................................................................... 6 Mile Post System ................................................................................................................................................. 6 Traffic Volume Data............................................................................................................................................. 7 Comparative Collision Rates ............................................................................................................................... 7 C. Program Procedures ......................................................................................................................................... 8 1. Fatal Collision Review .............................................................................................................................. 8 2. Site Specific Monitoring ............................................................................................................................ 8 3. Intersection High Incidence ...................................................................................................................... 9 4. Roadway Segment High Incidence ........................................................................................................ 11 5. Pedestrian High Incidence...................................................................................................................... 14 6. Bicycle High Incidence............................................................................................................................ 16 7. Intersection Signalization & All-Way Stop Monitoring ............................................................................ 18 8. Intersection Sight Distance & Clearance Intervals ................................................................................. 20 9. Run-off-Road .......................................................................................................................................... 22 10. Wet Pavement ........................................................................................................................................ 24 11. Snow/Ice ................................................................................................................................................. 26 12. Motorcycle High Incidence...................................................................................................................... 28

LIST OF FIGURES

Figure 1 – Yearly Cycle.............................................................................................................................................. 5 Figure 2 – Intersection High Incidence .................................................................................................................... 10 Figure 3 – Roadway Segment High Incidence......................................................................................................... 13 Figure 4 – Pedestrian High Incidence...................................................................................................................... 15 Figure 5 – Bicycle High Incidence............................................................................................................................ 17 Figure 6 – Intersection Signalization Monitoring ...................................................................................................... 19 Figure 7 – Intersection Sight Distance & Clearance Intervals ................................................................................. 21 Figure 8 – Run-off-Road .......................................................................................................................................... 23 Figure 9 – Wet Pavement ........................................................................................................................................ 25 Figure 10 – Snowy/Icy.............................................................................................................................................. 27 Figure 11 – Motorcycle High Incidence.................................................................................................................... 29

LIST OF TABLES

Table 1 – Program Element Summary....................................................................................................................... 3 Table 2 – Historical Collision Data ............................................................................................................................. 4

A. INTRODUCTION This handbook provides guidelines and information for implementation of the Placer County Traffic Accident Analysis System (TAAS). As such, it is comprised of tools, processes, and procedures for use by the County’s engineering staff. The TAAS was developed to enhance safety throughout the County’s roadway network. The TAAS accomplishes this by helping the County’s engineering staff to identify roadway segments and intersections in the County that may need safety improvements. The County’s engineering staff can then target these locations for detailed engineering investigations to determine what, if any, improvements should be implemented according to their engineering judgment. Engineering judgment is a crucial element of the TAAS. While this handbook includes methods to identify locations for engineering investigations, it does not prescribe the actions that should be taken as a result of these investigations. The appropriate action or non-action resulting from each investigation must be identified based on the judgment of the County’s engineering staff once their investigation is complete. Since engineering judgment must play such a crucial role, it must be defined. Engineering Judgment – the engineer’s evaluation of available pertinent data and information, and the application of appropriate engineering principles, experience, education, discretion, published standards or guidelines, and typical practices for the purpose of deciding upon the need for safety improvements and, if needed, deciding upon the safety improvement to be employed. Engineering judgment should be exercised by a licensed professional engineer or by an individual working under the supervision of an engineer using the procedures and criteria established by the engineer. Documentation of engineering judgment is not required; however, documentation of the final decisions and recommendations arising from the use of engineering judgment may be prepared. Implementation of the TAAS occurs on a yearly cyclical basis, as illustrated in Figure 1. The implementation timeline reflects key milestone dates and windows for the accomplishment of various program elements. Of particular importance is the need to have a finalized list of prioritized safety enhancement projects by the middle of December for consideration in the upcoming fiscal year’s budgeting process, which occurs in January. The TAAS includes core program elements, which are completed each year, along with program elements that are completed on a rotational basis such that each element is completed every 3-5 years. Each program element is briefly identified below, and a detailed description of each is provided in this handbook. Table 1 contains a summary of each program element. Core Program Elements •

Fatal Collision Review – review of all fatal collisions

•

Location Specific Monitoring – review and potential investigation of locations identified for monitoring

•

Intersection High Incidence – investigation of top 5 intersections

•

Roadway Segment High Incidence – investigation of top 5 roadway segments

•

Pedestrian High Incidence – investigation emphasizing school area and mid-block locations

•

Bicycle High Incidence – investigation emphasizing school area locations

Rotational Program Elements •

Intersection Signalization Monitoring – review of intersections with history of broadside collisions

•

Intersection Sight Distance & Clearance Intervals – investigation of intersections with history of right-ofway violations

•

Run-off-Road – investigation of locations with history of solo vehicle collisions

•

Wet Pavement – investigation of locations with history of collisions on wet pavement/during rainy weather

•

Snow/Ice – investigation of locations with history of collisions during winter conditions

•

Motorcycle High Incidence – review of roadway segments with a history of motorcycle collisions

SCOPE OF THE TAAS AND THIS HANDBOOK The TAAS is a tool that is intended to assist the County’s engineering staff in focusing their attention and efforts toward the most appropriate locations throughout the County for consideration of safety improvements. It is recognized that many roadways throughout the County do not conform with current design standards and guidelines; however, the fact that a roadway does not meet current design standards does not necessarily make safety improvements essential. Traffic and roadway engineering design standards and guidelines have evolved over many years; therefore, many roadways that do not display any safety deficiencies no longer meet the current standards simply due to the passage of time since their construction. Conversely, some roadways that meet current standards may display safety deficiencies. The TAAS recognizes that reconstructing all roadways that do not meet current design standards would be financially infeasible, and doing so would expend funds to upgrade many roadways that operate safely. The TAAS, therefore, relies on traffic accident history coupled with engineering judgment as the operational indicator of potentially needed safety improvements rather than compliance with design standards as the basis for identifying locations for further engineering investigation. This handbook is intended to provide guidelines and information for the implementation of the TAAS using engineering judgment. As such, this handbook does not intend to create or impose any standard of conduct or duty to the public. Further, this handbook is not intended to be a substitute for engineering knowledge, experience, or judgment. Initial implementation of the TAAS occurred midyear in 2009. Therefore, only core program elements were examined in this first year. Several rotational elements will be added in 2010.

HISTORICAL COLLISION STATISTICS The primary goal of the TAAS is to enhance safety on the County’s roadway network by reducing the number and severity of traffic collisions. A review of historical collision statistics provides a basis for assessing the effectiveness of the program. Table 2 provides a summary of relevant statistics that will be reviewed and updated annually.

TABLE 1 – PROGRAM ELEMENT SUMMARY Element Number

Program Element

Purpose & Goal

Frequency

Key Metric

Number of Resulting Investigations

Fatal Collision Review

To identify safety improvements prior to the emergence of a pattern of severe collisions.

Ongoing

All fatal collisions reviewed.

Varies. Average of 15-25 per year

Site Specific Monitoring

To review and evaluate locations identified as potentially having issues.

Annually

Engineering judgment.

Up to 10 locations per year

Intersection High Incidence

To identify and investigate intersections experiencing high collision rates.

Annually

Collision rate ranking.

5 locations per year

Roadway Segment High Incidence

To provide an overall review of the County’s roadway network identifying and investigating collision concentrations.

Annually

Engineering judgment along with collision rate ranking.

5 locations per year

Pedestrian High Incidence

To enhance pedestrian safety, particularly near schools.

Annually

Engineering judgment. Emphasis on 3 locations per year locations near schools.

Bicycle High Incidence

To enhance bicyclist safety, particularly near schools.

Annually

Engineering judgment. Emphasis on 3 locations per year locations near schools.

Intersection Signalization To identify intersections that may benefit from & Every 3-5 years signalization or all-way stop signs. All-Way Stop Monitoring

5 or more broadside collisions during 3 year period.

5 locations every 3-5 years

Intersection Sight Distance & Clearance Intervals

To identify high incidences of right-of-way violations that may have sight distance constraints or need for longer clearance intervals

Every 3-5 years

Engineering judgment along with collision rate ranking.

10 locations every 3-5 years

Run-Off-Road

To identify and investigate locations with history of severe solo vehicle collisions.

Every 3-5 years

Engineering judgment focusing on locations with 3 or more solo injury/fatal collisions within ¼ mile.

5 locations every 3-5 years

Wet Pavement

To identify and investigate locations that exhibit collisions during wet pavement conditions.

Every 3-5 years

Engineering judgment focusing on locations with 8 wet pavement collisions per mile.

5 locations every 3-5 years

Snow/Ice

To identify and investigate locations that exhibit collisions during snow or icy pavement conditions.

Every 3-5 years

Engineering judgment focusing on locations with 8 snowy/icy pavement collisions per mile.

5 locations every 3-5 years

Motorcycle High Incidence

To identify and investigate locations that have exhibited a concentration of motorcycle collisions.

Every 3-5 years

Engineering judgment focusing on locations with 2 or more motorcycle collisions within ¼ mile.

5 locations every 3-5 years

TABLE 2 â&#x20AC;&#x201C; HISTORICAL COLLISION DATA 5-Year (2004-2008)

Prior Year (2007)

Most Recent Year (2008)

Total

Average per Year

Total

% from Average

7,009

1,402

1,175

-16%

Fatal Collisions

Injury Collisions

Total Collisions

2,471

494

463

448

-9%

Pedestrian

+29%

Bicycle

-32%

Motorcycle

327

Run-off Road

2,331

466

412

453

-3%

Wet Pavement

905

181

141

-22%

Snow/Ice

621

124

180

+45%

Source: Placer County Crossroads Collision Database

Prior Year Project Budgeting

Winter Investigations

January

Traffic Count Collection

Initial Identification of Investigation Locations

February

March

Core Program Investigations

Final List of Investigation Locations

April

May

June

July

Project Evaluation & Prioritization

Rotational Program Investigations

August

September

October

November

Final Project List Seeking Funding Next Fiscal Year (by mid-December)

December

LEGEND Data Entry & Collection Data Analysis Evaluation, Prioritization, and Budgeting Investigations: Core Program (Annual) - Intersection High Incidence - Roadway Segment High Incidence - Pedestrian High Incidence - Bicycle High Incidence - Intersection Signalization Monitoring Rotational program (2-4 Elements Each Year) - Intersection Sight Distance - Run-off Road - Snow/Ice - Wet Pavement - Motorcycle High Incidence - Left-turn Pocket Monitoring

YEARLY CYCLE N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig1_YearlyCycle.ai

FIGURE 1

B. PROGRAM MODULES & COLLISION DATA The TAAS utilizes several tools to facilitate its effective utilization. Key attributes of each of these tools are described briefly below.

TRAFFIC COLLISION REPORTS The California Highway Patrol (CHP) prepares a traffic collision report for most 1 reported collisions that occur on the County’s roadway network. The traffic collision reports serve as the primary collision data source for the TAAS. Each traffic collision report is typically completed using a standard form known as the CHP 555, which provides key information based on the officer’s investigation, including location, directions of travel, type of collision, and primary collision factor. The CHP provides copies of these collision reports to the County, and the County enters data from these reports into their database of collision data, which is described below.

STATEWIDE INTEGRATED TRAFFIC RECORDS SYSTEM The Statewide Integrated Traffic Records System (SWITRS) is used as a secondary collision data source for the TAAS. SWITRS is a collision database that the CHP operates and maintains. Upon request, the County periodically obtains electronic collision data from SWITRS. The SWITRS data is used to crosscheck the collision data in the County’s database and add collisions that were not entered into the database based on the traffic collision reports. The County generally performs this crosscheck with SWITRS annually.

CROSSROADS SOFTWARE The Crossroads software package serves as the County’s database of collision data for the TAAS. Crossroads provides data fields that correspond to the traffic collision reports prepared by the CHP. The County transcribes this data into Crossroads. Crossroads also enables the County to query collision data in various ways, produce collision diagrams for intersections, and obtain source data files for use in the County’s geographic information system (GIS).

GEOGRAPHIC INFORMATION SYSTEM GIS is used to display collision data and facilitate its review by the County. Source data files called shapefiles are exported from the Crossroads software and displayed. Each traffic collision is represented by an icon that is located on a map of the County’s roadway network at the location where the collision occurred. User defined colors and symbols can be used to facilitate visual scans of the data as part of the TAAS.

MILE POST SYSTEM Mile post information is available on the County’s roadways. This information is used to enhance the accuracy of traffic collision data locations within the TAAS. Mile post information for paved County-maintained roadways that are at least one mile long is available within the County’s GIS system.

At their discretion, the CHP may elect not to complete a traffic collision report for collisions involving property damage only.

TRAFFIC VOLUME DATA The County is developing a database of traffic volume data for use in calculating traffic collision rates during the execution of the TAAS. Traffic volume data will be collected and added to the database during the annual TAAS cycle.

COMPARATIVE COLLISION RATES The TAAS utilizes collision rates to assist with the identification and ranking of locations for engineering investigations. Collision rates consider both the number of collisions at a location and the number of users who travel through that location. As a result, collision rates enable the engineer to â&#x20AC;&#x153;normalizeâ&#x20AC;? collision histories and make more meaningful comparisons. In addition, reference to average collision rates for various types of facilities is a helpful way to determine if a location is experiencing a higher than expected rate of collisions. Comparative collision rates have been published by Caltrans, and the published collision rates are included in the appendix.

C. PROGRAM PROCEDURES The processes and procedures for use by the County’s engineering staff in the execution of the TAAS are identified in this section of the handbook. These processes and procedures are intended to guide the County’s engineering staff as they identify roadway segments and intersections at which they will perform detailed engineering investigations to determine what, if any, improvements should be implemented according to their engineering judgment. The TAAS does not proscribe the manner in which these investigations should be performed. The program elements described below will result in lists of roadway segments and intersections at which engineering investigations are performed. It is probable that some locations will be identified under multiple program elements. In this case, only a single investigation at that intersection will be performed; however, the investigation will address the key issues of each element that the location was identified under. Further, the location would be counted under each element. For example, if an roadway segment is identified under both the pedestrian high incidence and the motorcycle high incidence elements, a single investigation would be performed that addresses both pedestrian and motorcycle issues, and this location would be counted under both elements.

1. FATAL COLLISION REVIEW Purpose & Goal – Fatal collision reviews respond to the most severe collisions that occur on County-controlled roadways so that safety improvements can be identified, if needed, prior to the development of a pattern of severe collisions. Frequency – Ongoing. Review of each individual fatal collision is to be performed upon receipt of the traffic collision report in the County’s Public Works department. Key Metric – All fatal collisions on County-controlled roadways are to be reviewed. Procedure – An engineer is to review the traffic collision report for all fatal collisions that occur on Countycontrolled roadways. The engineer is to exercise engineering judgment to identify if a site visit or additional investigation is needed. If needed, an investigation is to be performed, and documentation of the investigation may be prepared along with recommended actions, if any.

2. SITE SPECIFIC MONITORING Purpose & Goal – Site specific monitoring enables the County to continue reviewing and evaluating locations that were identified as having potential issues, but the engineer did not recommend actions for immediate implementation. Frequency – Annually. This is a core element of the TAAS. Key Metric – Engineering judgment is used to identify locations that are placed on the list for site specific monitoring. Engineering judgment is also used to review collision history and determine appropriate next-steps. Procedure – A list of locations for inclusion in the site specific monitoring element will be created during 2009. The list will identify the location along with the issue(s) that are being monitored. Once established the list will be included in this handbook, and it will be updated annually. In subsequent years, up to 10 locations will be reviewed from the list of locations. The review will be conducted by an engineer who will exercise engineering judgment to determine if a full investigation should be performed. If a full investigation is not needed, the engineer will exercise engineering judgment to determine if the location should remain on the site specific monitoring list or if the location should be removed from the list. If the location remains on the list it will be moved to the bottom of the list and other locations will move up for review in subsequent years.

3. INTERSECTION HIGH INCIDENCE Purpose & Goal – Intersections generally experience the highest collision rates within a roadway network due to the convergence of conflicting travel demands. This program element identifies Country-controlled intersections that are experiencing the highest collision rates. Frequency – Annually. This is a core element of the TAAS. Key Metric – The intersections that display the 5 highest collision rates (collisions per million entering vehicles) among County-controlled intersections are identified for investigation. All intersections with 2 or more collisions involving fatalities or severe injuries are automatically included in the 5 intersections that are to be investigated. An intersection must have experienced at least 5 collisions over a three-year period to have an investigation performed. Procedure 1. Obtain an Intersection High Incidence query from the Crossroads database a. Select the most recent 3-year period for which data is available b. Set minimum number of collisions at 5 c.

Enter 30 in the Top ___ Locations box at top of page 1 of the query attributes

d. Select “No” under the State Highway drop down menu on page 2 of the query attributes e. Print out a Collision Severity Summary 2. Identify all County-controlled intersections listed on the Collision Severity Summary report 3. Calculate collision rates at each County-controlled intersection a. Review County traffic count database for ADT on each intersecting roadway b. Collect new ADT counts as needed c.

Use ADT to calculate collision rate (collisions per million entering vehicles)

4. Reorder list of County-controlled intersections on the Collision Severity Summary report based on descending collision rate 5. For the top 5 intersections, identify if a past investigation has been performed within the past 36 months a. No investigation is required at an intersection that has been investigated within the past 24 months b. Review accident history and prior investigation report at intersections that have been investigated within the past 36 months. No investigation is required; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 6. Finalize the list of top 5 intersections a. Removing intersections not requiring an investigation due to a past investigation b. Advance intersections into the top 5 to replace those that were removed c.

Automatically include any intersection that has 2 or more collisions involving fatalities or severe injuries.

7. Perform an engineering investigation at each of the top 5 intersections 8. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

Intersection High Incident Report - 3yr Period - Minimum 5 Coll. - Top 30 Locations - State Highway = “NO”

Collision Severity Summary

Decision

Interim Work Product

Document Ouput

No Action Required

County Controlled?

YES

Traffic Count Available?

Collect New ADT Counts

Termination Point

YES

Calculate Collision Rate

Re-order intersections by descending rate

Preliminary List of Top 5 Intersections

No Action Required

YES

Investigated in past 24 months?

Investigated in past 36 months?

YES

Engineer Suggest ReInvestigation?

No Action Required

NO YES

Document Investigation

Perform Investigations

Finalized List of Top 5 Intersections

Finalize Investigation List: - Advance to replace those dropped due to prior investigation. - Include all with 2+ Fatal or Severe Injury.

INTERSECTION HIGH INCIDENCE N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig2_IntHighInc.ai

FIGURE 2

4. ROADWAY SEGMENT HIGH INCIDENCE Purpose & Goal – The roadway segment high incidence element of the TAAS provides an overall review of the County’s roadway network. A large area of the County is low-density rural with few major intersections, mountainous terrain, and winding roadways. This element provides a review of these areas of the County along with roadway segments in the more urbanized areas of the County. Frequency – Annually. This is a core element of the TAAS. Key Metric – Using engineering judgment, a combination of collision rate (collisions per million vehicle miles) and collision density (collisions per mile) is used to identify 5 roadway segments for engineering investigation. Generally, a roadway segment must have 6 or more collisions within a ½ mile to warrant an investigation. Procedure 1. Obtain shapefile of all collision data from the Crossroads database a. Run General Query and output GIS shapefile b. Select the most recent 3-year period for which data is available 2. Import shapefile into ArcExplorer 3. Create plotted maps showing all collisions for manual review a. Color code based on severity (EXTENT) b. Show mile post c.

Include roadway centerline file

Use ADT to calculate collision rate (collisions per million vehicle miles)

6. Calculate collision density rate at each segment identified as a potential collision concentration (collisions per mile). 7. Create two ordered lists of the identified roadway segments a. One based on descending collision rate (collisions per million vehicle miles) b. One based on descending collision density (collisions per mile) 8. Obtain a Midblock High Incidence report from the Crossroads database a. Select the most recent 3-year period for which data is available 9. Use engineering judgment to select the top 5 roadway segments based upon the two ordered lists and the midblock high incidence report. 10. For the top 5 roadway segments, identify if a past investigation has been performed within the past 36 months

a. No investigation is required of a roadway segment that has been investigated within the past 24 months b. Review accident history and prior investigation report at intersections that have been investigated within the past 36 months. No investigation is required; however, an investigation may be performed if circumstances warrant per the engineerâ&#x20AC;&#x2122;s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 11. Finalize the list of top 5 roadway segments a. Removing segments not requiring an investigation due to a past investigation b. Advance segments into the top 5 to replace those that were removed 12. Perform an engineering investigation at each of the top 5 roadway segments 13. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

GIS - Color = Extent - Label = MilePost

General Query GIS Shapefile

Decision

- 3 Year Period Interim Work Product

Document Ouput

Scan Network Plots of Entire County

- Identify all segments with 6 or more collisions within 1/2 mile

Traffic Count Available?

Collect New ADT Counts

Termination Point

YES

- Calculate Collision Rate - Calculate Collision Density

Two Ordered Lists

Exercise Engineering Judgement to ID Top 5 Segments

Midblock High Incident Report

Crossroads Database

- 3yr Period

No Action Required YES Preliminary List of top 5 Roadway segments

Investigated in Past 24 Months?

Investigated in Past 36 Months?

YES

Engineer Suggest Reinvestigation?

No Action Required

NO YES

Document Investigation

Perform Investigations

Finalized List of top 5 Roadway Segments

Finalize Investigation List - Advance to replace those dropped due to prior investigation

ROADWAY SEGMENT HIGH INCIDENCE N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig3_RoadwaySeg_HI.ai

FIGURE 3

5. PEDESTRIAN HIGH INCIDENCE Purpose & Goal – The pedestrian high incidence element seeks to enhance the safety of pedestrians on Countycontrolled roadways, particularly near schools. Frequency – Annually. This is a core element of the TAAS. Key Metric – Engineering judgment is used to identify the top 3 pedestrian collision locations for investigation. Locations located within ½ mile of a school are emphasized. This element seeks to identify specific spot-locations that have exhibited pedestrian collisions, so locations with 2 or more pedestrian collisions within ¼ mile are targeted. Procedure 1. Obtain shapefile of all pedestrian related collision data from the Crossroads database a. Run 3 General Queries and append results b. Select the most recent 3-year period for which data is available for each query c.

Query 1: Select Collision Type = “Vehicle – Pedestrian”

d. Query 2: Select Involved With = “Pedestrian” e. Query 3: Select Party Type = “Pedestrian” f.

Export shapefile after the results of all three queries are appended

2. Import shapefile into ArcExplorer 3. Create plotted maps showing all collisions for manual review a. Color code based on severity (EXTENT) b. Show mile post c.

Include roadway centerline file

d. Show school locations e. Resulting plots should cover entire county at a scale that enables effective manual scanning and data analysis 4. Perform manual scan of roadway network to identify potential pedestrian collision concentrations a. Identify all locations with 2 or more pedestrian collisions within ¼ mile b. Note if identified location is within ½ mile of a school 5. Use engineering judgment to select the top 3 pedestrian collision locations. Emphasize locations that are within ½ mile of a school. 6. For the top 3 pedestrian collision locations, identify if a past investigation has been performed within the past 36 months a. No investigation is required of a location that has been investigated within the past 24 months b. Review accident history and prior investigation report at locations that have been investigated within the past 36 months. No investigation is required; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 7. Finalize the list of top 3 pedestrian collision locations a. Removing locations not requiring an investigation due to a past investigation b. Advance locations into the top 3 to replace those that were removed 8. Perform an engineering investigation at each of the top 3 pedestrian collision location 9. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

GIS - Color = Extent - Show MilePost Layer - Show Schools

3 General Queries 1. Collision Type = “Vehicle-Pedestrian” 2. Involved with = “Pedestrian” 3. Party Type = “Pedestrian”

GIS Shapefile

Decision

Interim Work Product

- Each with 3 Year Period

Document Ouput

Scan Network - Identify all locations with 2 or more Pedestrian Collisions within 1/4 mile - Note Locations within 1/2 of School

Plots of Entire County

Exercise Engineering Judgement to ID Top 3 Pedestrian Collision Locations

Preliminary List of Top 3 Pedestrian Collision Locations

Termination Point

Investigated in Past 24 Months?

YES

No Action Required

NO No Action Required

Engineer Suggest Reinvestigation?

YES

Investigated in Past 36 Months?

NO YES Finalize Investigation List - Advance to replace those dropped due to prior investigation

Document Investigation

Perform Investigations

Finalized List of Top 3 Pedestrian Collision Locations

PEDESTRIAN HIGH INCIDENCE N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig4_PedHighIncident.ai

FIGURE 4

6. BICYCLE HIGH INCIDENCE Purpose & Goal – The bicycle high incidence element seeks to enhance the safety of bicyclists on Countycontrolled roadways, particularly near schools. Frequency – Annually. This is a core element of the TAAS. Key Metric – Engineering judgment is used to identify the top 3 bicycle collision locations for investigation. Locations located within ½ mile of a school are emphasized. This element seeks to identify specific spot-locations that have exhibited bicycle collisions, so locations with 2 or more bicycle collisions within ¼ mile are targeted. Procedure 1. Obtain shapefile of all bicycle related collision data from the Crossroads database a. Run 2 General Queries and output GIS shapefile b. Select the most recent 3-year period for which data is available for each shapefile c.

Query 1: Select Involved With = “Bicycle”

d. Query 2: Select Party Type = “Bicycle” e. Export shapefile after results of both queries are appended 2. Import shapefile into ArcExplorer 3. Create plotted maps showing all collisions for manual review a. Color code based on severity (EXTENT) b. Show mile post c.

Include roadway centerline file

d. Show school locations e. Resulting plots should cover entire county at a scale that enables effective manual scanning and data analysis 4. Perform manual scan of roadway network to identify potential bicycle collision concentrations a. Identify all locations with 2 or more bicycle collisions within ¼ mile b. Note if identified location is within ½ mile of a school 5. Use engineering judgment to select the top 3 bicycle collision locations. Emphasize locations that are within ½ mile of a school. 6. For the top 3 bicycle collision locations, identify if a past investigation has been performed within the past 36 months a. No investigation is required of a location that has been investigated within the past 24 months b. Review accident history and prior investigation report at locations that have been investigated within the past 36 months. No investigation is required; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 7. Finalize the list of top 3 bicycle collision locations a. Removing locations not requiring an investigation due to a past investigation b. Advance locations into the top 3 to replace those that were removed 8. Perform an engineering investigation at each of the top 3 bicycle collision locations 9. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

2 General Queries

GIS - Color = Extent - Show MilePost Layer - Show Schools

Decision

1. Involved with = “Bicycle” 2. Party Type = “Bicycle”

GIS Shapefile

- Each with 3 Year Period

Interim Work Product

Document Ouput

Scan Network - Identify all locations with 2 or more Bicycle Collisions within 1/4 mile - Note Locations within 1/2 of School

Plots of Entire County

Exercise Engineering Judgement to ID Top 3 Bicycle Collision Locations

Preliminary List of Top 3 Bicycle Collision Locations

Termination Point

Investigated in Past 24 Months?

YES

No Action Required

NO No Action Required

Engineer Suggest Reinvestigation?

YES

Investigated in Past 36 Months?

NO YES Finalize Investigation List - Advance to replace those dropped due to prior investigation

Document Investigation

Perform Investigations

Finalized List of Top 3 Bicycle Collision Locations

BICYCLE HIGH INCIDENCE N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig5_BikeHighIncident.ai

FIGURE 5

7. INTERSECTION SIGNALIZATION & ALL-WAY STOP MONITORING Purpose & Goal – Signalization or all-way stop sign implementation can be an effective safety improvement at unsignalized intersections that have a history of collisions involving vehicles traveling perpendicularly to each other. This element is intended to monitor and identify intersections that may benefit from signalization or all-way stop signs. Frequency – Every 3-5 years. This is a rotational program element. Key Metric – An investigation is performed at County-controlled unsignalized intersections that have experienced 5 or more broadside collisions within the past three years. Procedure 1. Obtain an Intersection High Incidence query from the Crossroads database a. Select the most recent 3-year period for which data is available b. Set minimum number of collisions at 3 c.

Enter 30 in the Top ___ Locations box at top of page 1 of the query attributes

d. Set collision type to Broadside e. Select “No” under the State Highway drop down menu on page 2 of the query attributes f.

Print out a Collision Severity Summary

2. Identify all County-controlled intersections listed on the Collision Severity Summary report 3. Separate County-controlled intersections listed on the Collision Severity Summary report into signalized versus unsignalized intersections 4. For each unsignalized intersection, identify if an investigation was performed during the previous time that the intersection signalization and all-way stop monitoring element of the rotational program was conducted a. No investigation is required at an intersection that was investigated during the previous time this element of the rotational program was conducted; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 5. Perform an engineering investigation at 5 non-signalized intersections identified using engineering judgment from those intersections remaining after the review of past investigations 6. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

Intersection High Incident Report - Coll. Type = Broadside - 3 Year Period - Minimum 3 Collisions - Top 30 Locations - State Highway = “No”

Collision Severity Summary

Decision

Interim Work Product

Document Ouput

No Action Required

County Controlled?

YES

Signalized?

YES

No Action Required

Termination Point

Investigated most recent past rotational cycle?

YES

Engineer Suggest ReInvestigation?

No Action Required

YES

Exercise Engineering Judgement to Identify 5 Intersections for Investigation

Finalized List of Intersections

Document Investigation

Perform Investigations

INTERSECTION SIGNALIZATION & ALL-WAY STOP MONITORING N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig6_IntSignal.ai

FIGURE 6

8. INTERSECTION SIGHT DISTANCE & CLEARANCE INTERVALS Purpose & Goal – Right-of-way violations can be indicative of sight distance constraints at unsignalized locations or the need for longer clearance intervals at signalized intersections. This element uses collision history related to right-of-way violations to identify locations that may have sight distance constraints or need for longer clearance intervals. Frequency – Every 3-5 years. This is a rotational program element. Key Metric – This element results in investigations of the 10 intersections with the most collisions attributed to right-of-way violations. A minimum of 3 such collisions must have occurred over the previous 3 years. Procedure 1. Obtain an Intersection High Incidence query from the Crossroads database a. Select the most recent 3-year period for which data is available b. Set minimum number of collisions at 3 c.

Enter 30 in the Top ___ Locations box at top of page 1 of the query attributes

d. Set primary collision factor to “Auto R/W Violation” e. Select “No” under the State Highway drop down menu on page 2 of the query attributes f.

Print out a Collision Severity Summary

2. Identify all County-controlled intersections listed on the Collision Severity Summary report 3. Separate County-controlled intersections listed on the Collision Severity Summary report into signalized versus unsignalized intersections 4. For each country-controlled intersection, identify if an investigation was performed during the previous time that the intersection sight distance and clearance interval element of the rotational program was conducted a. No investigation is required at an intersection that was investigated during the previous time this element of the rotational program was conducted; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 5. Perform an engineering investigation at 5 signalized and 5 non-signalized intersections that are identified using engineering judgment from those intersections remaining after the review of past investigations a. Focus on sight distance at unsignalized locations b. Focus on clearance intervals at signalized locations 6. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

Collision Severity Summary

Intersection High Incident Report - Primary Collision Factor = “Auto R/W Violation” - 3 Year Period - Minimum 3 Collisions - Top 30 Locations - State Highway = “No”

Decision

Interim Work Product

Document Ouput

County Controlled?

No Action Required

Termination Point

YES

Investigated most recent past rotational cycle?

YES

Engineer Suggest ReInvestigation?

No Action Required

YES

Exercise Engineering Judgement to Identify 5 Signalized and 5 Non-signalized Intersections for Investigation

Finalized List of Intersections

Document Investigation

Perform Investigations - Focus on Sight Distance at unsignalized Locations - Focus on Clearance Intervals at signalized Locations

INTERSECTION SIGHT DISTANCE & CLEARANCE INTERVALS N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig7_IntSightDist_ClearInterval.ai

FIGURE 7

9. RUN-OFF-ROAD Purpose & Goal – The run-off-road element identifies locations with a history of severe solo vehicle collisions. Many of the County-controlled roadways are rural with winding two-lane roadways in mountainous terrain that are susceptible to solo run-off-road conditions. Investigations of areas on these roadways with a history of severe solo collisions may reveal issues such as fixed objects along the roadside that need to be protected or relocated, curves that need additional warning devices, etcetera. Frequency – Every 3-5 years. This is a rotational program element. Key Metric –This element seeks to identify specific spot-locations that have exhibited run-off-road collisions, so locations with 3 or more such collisions within ¼ mile are targeted. To focus attention on the most critical locations, it considers only injury and fatal collisions. Procedure 1. Obtain shapefile of all solo, injury/fatal collision data from the Crossroads database a. Run General Query and output GIS shapefile b. Select the most recent 3-year period for which data is available for each shapefile c.

Select highest degree of injury as “All Injury and Fatal Collisions”

d. Select number of parties as “= 1” 2. Import shapefile into ArcExplorer 3. Create plotted maps showing all collisions for manual review a. Color code based on severity (EXTENT) b. Show mile post c.

Include roadway centerline file

d. Resulting plots should cover entire county at a scale that enables effective manual scanning and data analysis 4. Perform manual scan of roadway network to identify potential collision concentrations a. Identify all roadway segments with 3 or more collisions within ¼ mile b. Extend beyond ¼ mile segment to join adjacent locations on the same roadway with at least 3 collisions per ¼ mile. Consider the extended location as one segment. 5. Use engineering judgment to select the top 5 run-off-road collision locations. 6. For the top 5 run-off-road collision locations, identify if an investigation was performed during the previous time that the run-off-road element of the rotational program was conducted a. No investigation is required at a location that was investigated during the previous time this element of the rotational program was conducted; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 7. Finalize the list of top 5 run-off-road collision locations a. Removing locations not requiring an investigation due to a past investigation b. Advance locations into the top 5 to replace those that were removed 8. Perform an engineering investigation at each of the top 5 run-off-road collision location 9. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

GIS - Color = Extent - Show MilePost Layer

GIS Shapefile

General Query - 3 Year Period - Select highest degree of injury as “All Injury and Fatal Collisions” - Select number of parties as “=1”

Decision

Interim Work Product

Document Ouput

Plots of Entire County

Scan Network - Identify all locations with 3 or more Run-off-Road Collisions within 1/4 mile - Note total number of injuries & fatalities in each segment

Exercise Engineering Judgement to ID Top 5 Run-off-Road Collision Locations

Termination Point

List of Top 5 Run-off-Road Collision Locations

Investigated most recent past rotational cycle?

YESS

Engineer YES ReSuggest Investigation?

No Action Required

YES

Finalize Investigation List - Advance to replace those dropped due to prior investigation

Document Investigation

Perform Investigations

Finalized List of Top 5 Run-off-Road Collision Locations

RUN-OFF-ROAD N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig8_RunOffRoad.ai N: N:\ N:\2 N ::\2 :\ \\2 20 00 007 007P 07P 07P 07 7Proj roje rro oje oj oje ject cts\ cts\ cts tts s\2 s\ 24 49 4

FIGURE 8

10. WET PAVEMENT Purpose & Goal – Some locations that do not otherwise display safety issues may need improvements that are directly related to wet pavement conditions. These roadways may need pavement rehabilitation to improve the frictional properties of the pavement or drainage improvements. This element identifies locations that exhibit collisions during wet pavement conditions. Frequency – Every 3-5 years. This is a rotational program element. Key Metric – This element uses engineering judgment to identify the top 5 locations with 4 or more wet pavement collisions along with a minimum density of 8 per mile. Procedure 1. Obtain shapefile of all wet pavement collision data from the Crossroads database a. Run General Query and output GIS shapefile b. Select the most recent 3-year period for which data is available for each shapefile c.

Select road surface condition as “Wet”

2. Import shapefile into ArcExplorer 3. Create plotted maps showing all collisions for manual review a. Color code based on severity (EXTENT) b. Show mile post c.

Include roadway centerline file

d. Resulting plots should cover entire county at a scale that enables effective manual scanning and data analysis 4. Perform manual scan of roadway network to identify potential collision concentrations a. Identify all roadway segments with 4 or more collisions within ½ mile b. Extend beyond ½ mile segment to join adjacent locations on the same roadway with at least 4 collisions per ½ mile (8 per mile). Consider the extended location as one segment. 5. Use engineering judgment to select the top 5 wet pavement collision locations. 6. For the top 5 wet pavement collision locations, identify if an investigation was performed during the previous time that the wet pavement element of the rotational program was conducted a. No investigation is required at a location that was investigated during the previous time this element of the rotational program was conducted; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 7. Finalize the list of top 5 wet pavement collision locations a. Removing locations not requiring an investigation due to a past investigation b. Advance locations into the top 5 to replace those that were removed 8. Perform an engineering investigation at each of the top 5 wet pavement collision location 9. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

GIS - Color = Extent - Show MilePost Layer

General Query GIS Shapefile

Decision

- 3 Year Period - Select road surface condition as “Wet”

Interim Work Product

Document Ouput

Scan Network Plots of Entire County

- Identify all locations with 4 or more Wet Pavement Collisions within 1/2 mile

Exercise Engineering Judgement to ID Top 5 Wet Pavement Collision Locations

Termination Point

List of Top 5 Wet Pavement Collision Locations

Investigated most recent past rotational cycle?

YES YE

Engineer Engineer Investigated Suggest gg most recentRepast Investigation? g cycle? rotational

N NO

No Action Required

YES

Finalize Investigation List - Advance to replace those dropped due to prior investigation

Document Investigation

Perform Investigations

Finalized List of Top 5 Wet Pavement Collision Locations

WET PAVEMENT N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\July2009\Fig9_WetPavement.ai

FIGURE 9

11. SNOW/ICE Purpose & Goal – Many County-controlled roadways are located in mountainous terrain at high elevations, which experience snow and ice during the winter. Some locations that do not otherwise display safety issues may need improvements that are directly related to snowy/icy pavement conditions. These roadways may need more proactive winter pavement maintenance, drainage improvements, or warning signage. This element identifies locations that exhibit collisions during snowy/icy pavement conditions. Frequency – Every 3-5 years. This is a rotational program element. Key Metric – This element uses engineering judgment to identify the top 5 locations with snowy/icy pavement collisions. Procedure 1. Obtain shapefile of all snowy/icy pavement collision data from the Crossroads database a. Run General Query and output GIS shapefile b. Select the most recent 3-year period for which data is available for each shapefile c.

Select road surface condition as “Snowy or Icy”

2. Import shapefile into ArcExplorer 3. Create plotted maps showing all collisions for manual review a. Color code based on severity (EXTENT) b. Show mile post c.

Include roadway centerline file

d. Resulting plots should cover entire county at a scale that enables effective manual scanning and data analysis 4. Perform manual scan of roadway network to identify potential collision concentrations a. Identify all roadway segments with 4 or more collisions within ½ mile b. Extend beyond ½ mile segment to join adjacent locations on the same roadway with at least 4 collisions per ½ mile (8 per mile). Consider the extended location as one segment. 5. Use engineering judgment to select the top 5 snowy/icy pavement collision locations. 6. For the top 5 snowy/icy pavement collision locations, identify if an investigation was performed during the previous time that the snow/ice element of the rotational program was conducted a. No investigation is required at a location that was investigated during the previous time this element of the rotational program was conducted; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 7. Finalize the list of top 5 snowy/icy pavement collision locations a. Removing locations not requiring an investigation due to a past investigation b. Advance locations into the top 5 to replace those that were removed 8. Perform an engineering investigation at each of the top 5 snowy/icy pavement collision location 9. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

GIS - Color = Extent - Show MilePost Layer

General Query GIS Shapefile

Decision

- 3 Year Period - Select road surface condition as “Snowy or Icy”

Interim Work Product

Document Ouput

Scan Network Plots of Entire County

- Identify all locations with 4 or more Snowy/Icy Pavement Collisions within 1/2 mile

Exercise Engineering Judgement to ID Top 5 Snowy/Icy Collision Locations

Termination Point

List of Top 5 Snowy/Icy Collision Locations

Investigated most recent past rotational cycle?

YES YE

Engineer Engineer Investigated Suggest gg most recentRepast Investigation? g cycle? rotational

N NO

No Action Required

YES

Finalize Investigation List - Advance to replace those dropped due to prior investigation

Document Investigation

Perform Investigations

Finalized List of Top 5 Snowy/Icy Collision Locations

SNOWY/ICY N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\June2009\Fig10_SnowyIcy.ai

FIGURE 10

12. MOTORCYCLE HIGH INCIDENCE Purpose & Goal – The motorcycle high incidence element seeks to enhance the safety of motorcyclists on County-controlled roadways. Frequency – Every 3-5 years. This is a rotational program element. Key Metric – Engineering judgment is used to identify the top 5 motorcycle collision locations for investigation. This element seeks to identify specific spot-locations that have exhibited motorcycle collisions, so locations with 2 or more motorcycle collisions within ¼ mile are targeted. Procedure 1. Obtain shapefile of all motorcycle related collision data from the Crossroads database a. Run General Query and output GIS shapefile b. Select the most recent 3-year period for which data is available for each shapefile c.

Select Vehicle Type = “Motorcycle”

2. Import shapefile into ArcExplorer 3. Create plotted maps showing all collisions for manual review a. Color code based on collision type (COLL_TYPE) b. Show mile post c.

Include roadway centerline file

d. Resulting plots should cover entire county at a scale that enables effective manual scanning and data analysis 4. Perform manual scan of roadway network to identify potential motorcycle collision concentrations a. Identify all locations with 2 or more motorcycle collisions within ¼ mile 5. Use engineering judgment to select the top 5 motorcycle collision locations. 6. For the top 5 motorcycle collision locations, identify if an investigation was performed during the previous time that the motorcycle high incidence element of the rotational program was conducted a. No investigation is required at a location that was investigated during the previous time this element of the rotational program was conducted; however, an investigation may be performed if circumstances warrant per the engineer’s judgment (e.g., change in collision history characteristics, change in roadway characteristics, change in travel characteristics, etc.) 7. Finalize the list of top 5 motorcycle collision locations a. Removing locations not requiring an investigation due to a past investigation b. Advance locations into the top 5 to replace those that were removed 8. Perform an engineering investigation at each of the top 5 motorcycle collision locations 9. Document each investigation and recommended actions, if any

LEGEND Crossroads Database

Operation

Process

GIS - Color = Coll_Type - Show MilePost Layer

General Query GIS Shapefile

Decision

- 3 Year Period - Select a vehicle type as “Motorcycle”

Interim Work Product

Document Ouput

Scan Network Plots of Entire County

- Identify all locations with 2 or more Motorcycle Collisions within 1/4 mile

Exercise Engineering Judgement to ID Top 5 Motorcycle Collision Locations

Termination Point

List of Top 5 Motorcycle Collision Locations

Investigated most recent past rotational cycle?

NO N O

YES YE

Engineer Engineer Investigated Suggest gg most recentRepast Investigation? g cycle? rotational

N NO

No Action Required

YESS

Finalize Investigation List - Advance to replace those dropped due to prior investigation

Document Investigation

Perform Investigations

Finalized List of Top 5 Motorcycle Collision Locations

MOTORCYCLE HIGH INCIDENCE N:\2007Projects\2498_Placer_Accident_Analysis\Graphics\AI\June2009\Fig12_Motorcycle HI.ai

FIGURE 11

APPENDIX PUBLISHED AVERAGE COLLISION RATES