Maryland 2006 Five Percent Report
This report is in response to the Federal requirement that each state describe at least 5 percent of its locations currently exhibiting the most severe highway safety needs, in accordance with Sections 148(c)(1)(D) and 148(g)(3)(A), of Title 23, United States Code. Each state’s report is to include potential remedies to the hazardous locations identified; estimated costs of the remedies; and impediments to implementation of the remedies other than costs. The reports included on this Web site represent a variety of methods utilized and various degrees of road coverage. Therefore, this report cannot be compared with the other reports included on this Web site.
Protection from Discovery and Admission into Evidence—Under 23 U.S.C. 148(g)(4) information collected or compiled for any purpose directly relating to this report shall not be subject to discovery or admitted into evidence in a Federal or State court proceeding or considered for other purposes in any action for damages arising from any occurrence at a location identified or addressed in the reports. |
Additional information, including the specific legislative requirements, can be found in the guidance provided by the Federal Highway Administration,
http://safety.fhwa.dot.gov/safetealu/fiveguidance.htm.
Maryland Highway Safety Improvement Program (HSIP)
Annual Report
Fiscal Year 2006
Maryland Department of Transportation
Maryland State Highway Administration
Office of Traffic and Safety
Traffic Development & Support Division
Five Percent Report
"Section 1401 of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (Public Law 109-59), or SAFETEA-LU, amended Section 148 of Title 23, United Sates Code, to create a new Highway safety Improvement Program (HSIP) as a "core" FHWA program with specific funding. As a condition for obligating HSIP funds, Section 148(c)(1)(D) requires States to prepare an annual report that describes not less than 5 percent of their public road locations exhibiting the most severe safety needs. The legislation requires that these reports also include an assessment of potential remedies at the locations identified, the estimated costs of the remedies, and impediments to their implementation other than costs". See Footnote 1.
Current Methodology Used To Identify Hazardous Locations
"Because Section 148(b)(2) states that the intended purpose of the HSIP is to achieve a significant reduction in fatalities and serious injuries on public roads, it is expected that the State's methodologies used in identifying locations for inclusion in the "5 percent reports" will focus on fatalities and serious injuries. If a State's current methodology does not include all public roads and/or fatalities and serious injuries, it may use its current methodology to prepare the initial "5 percent report", but should include a discussion of its plans and timetable to achieve full public road coverage and the criteria related to fatalities and serious injuries." See Footnote 1. Exhibit 7 explains the existing methodology for identifying high hazard locations. The term used by SHA is Candidate Safety Improvement Locations (CSIL). Currently, only State roads are evaluated for the annual CSIL which is at variance with FHWA requirements. Fatal and serious injury crashes are included, but are not the primary selection criteria. Several issues listed below will be addressed prior to the August 31, 2009 requirement to "...cover all public roads". See Footnote 2.
- Site specific collision data is unavailable to SHA for Baltimore City surface streets.
- Microfilm copies of MAARS collision reports on Baltimore City surface streets are not available to SHA.
- Baltimore City is undertaking its own process of identifying hazardous locations and needed safety improvements.
- Traffic volumes for non-SHA maintained highways in Maryland is incomplete preventing the full use of a rate based model for evaluation of hazardous locations off the SHA system.
- Responsibility in reviewing non-State maintained systems.
- Possible methods for basing the 5 Percent Report location on fatalities and serious injuries, given that only 6,000 such accidents occur on 65,000 public roads annually.
Site Specific Locations
"Section 148(c) (1)(D)(ii) requires that the reports include an assessment of potential remedies, their estimated costs, and impediments to their implementation other than cost for each location identified." See Footnote 3. In FY 2006 based on 2004 crash data, there were 140 Priority Candidate Safety Improvement Locations. Three locations were selected because their improvements were federally funded while the other four were based on a weighted severity index given heavy weight to fatalities and incapacitating injuries. The analysis of 5% (7 of 140) of these locations is shown below in Table V. Estimated costs were the most current figures available at the time of this report and are subject to final adjustments.
Table V
5% of Highway Locations Exhibiting the Most Severe Safety Needs
| Location | Potential Remedies | Estimated Cost |
Implementation Impediments |
Comments |
|---|---|---|---|---|
| MD 715 at Old Philadelphia Road | An existing intersection control beacon was converted to a fully actuated traffic signal. | $ 68,000 | None | 26 reported accidents at this location between 2002 to 2004. Severity rate was 8.41 accidents per 100 million vehicle miles in 2004. Accident rate was 2.90 accidents per 100 million vehicle miles in 2004. This location was also a Priority Candidate Safety Improvement Intersection in prior years. |
| MD 174 at Thelma Avenue | This signal was fully reconstructed and put into operation. The diagonal mast arm was replaced with box span for better orientation and display of the signal heads. The signal heads were converted from 8 inch heads to 12 inch black heads for better visibility. Thelma Avenue approach was converted to exclusive permissive phasing. The signal now operates under fully actuated mode. State Highway Administration will reevaluate this location at a later date. | $ 35,000 | None | 17 reported accidents at this location between 2002 to 2004. Severity rate was 5.85 accidents per 100 million vehicle miles in 2004. Accident rate was 2.34 accidents per 100 million vehicle miles in 2004. This location was also a Candidate Safety Improvement Intersection in prior years. |
| MD 227 at Middletown and Turkey Hill Roads | Install advance junction assembly signs on the northbound and southbound approaches. Install "Crossroads" warning sign along the westbound approach of MD 227. Remove the oak tree in the southwest quadrant. Install "STOP AHEAD" pavement markings and rumble strips along each minor street approach. Remove the existing passing zone west of the intersection. Work order submitted in March 2006. Possible future roundabout project. | $ 3,300 | None | 31 reported accidents at this location between 2002 to 2004. Severity rate was 6.37 accidents per 100 million vehicle miles in 2004. Accident rate was 2.92 accidents per 100 million vehicle miles in 2004. This location was also a Priority Candidate Safety Improvement Intersection in prior years. |
| 173 at Valley Road and Duvall Highway | Northbound left-turn phasing was converted from exclusive permissive to exclusive phasing. State Highway Administration will reevaluate at a later date. | $ 2,600 | None | 54 reported accidents at this location between 2002 to 2004. Severity rate was 6.91 accidents per 100 million vehicle miles in 2004. Accident rate was 3.34 accidents per 100 million vehicle miles in 2004. This location was also a Priority Candidate Safety Improvement Intersection in prior years. |
| MD 3 BU at Greenbranch Lane | Dual left turn lanes were constructed from northbound MD 3 Business into Wal Mart. Signal phasing for northbound and southbound left turn was converted from exclusive permissive to exclusive along with installation of black signal heads. | $ 174,000 | None | 47 reported accidents at this location between 2002 to 2004. Severity rate was 2.85 accidents per 100 million vehicle miles in 2004. Accident rate was 1.53 accidents per 100 million vehicle miles in 2004. This location was also a Priority Candidate Safety Improvement Intersection in prior years. Intersection was on the Fiscal Year 2005 Hazard Elimination List Section 152 and Fiscal Year 2006 STP-23 USC 148g lists. $274,705 was the estimated cost for existing improvements. The federal portion of the project was estimated at $243,648. |
| US 301 at MD 300 | Reconstruct the intersection to provide left turns from northbound and southbound US 301 only. Cross movement will be restricted to right turns only, then using median crossover downstream for U turn, then right turn upon return to intersection. This is considered a J turn maneuver to cross US 301. Project is currently under construction (early 2006) with J turns in place. | $ 100,000 | None | 22 reported accidents at this location between 2002 to 2004. Severity rate was 2.73 accidents per 100 million vehicle miles in 2004. Accident rate was 1.19 accidents per 100 million vehicle miles in 2004. This location was also a Priority Candidate Safety Improvement Intersection in prior years. Intersection was on the Fiscal Year 2005 Hazard Elimination List Section 152. |
| MD 170 at MD 174 | The intersection was reconstructed and resurfaced along with extending the southbound left turn lane to accommodate the longer queue. Left turn phasing was converted from exclusive permissive to exclusive along northbound and southbound MD 170 on August 2, 2005. An after study was performed after the job was completed in 2005. To accommodate the left turn conflicts, the phasing for eastbound and westbound MD 174 from exclusive permissive to exclusive with the eastbound left turn as lead-lag. the following improvements are being considered which may alleviate congestion related accidents: (1) Constructing a double left turn lane with 400 feet of storage along eastbound MD 174 and a two directional left turn lane beyond that for a total distance of 800 feet, to accommodate turning traffic in the driveways. (2) Constructing two thru lanes along northbound and southbound MD 170. This will accommodate a double left turn movement from eastbound MD 174 to tie into the existing 4 lane section to the north. | $ 350,000 in 2004 $20,000 additional in 2006 | None | 49 reported accidents at this location between 2002 to 2004. Severity rate was 1.69 accidents per 100 million vehicle miles in 2004. Accident rate was 1.08 accidents per 100 million vehicle miles in 2004. This location was also a Priority Candidate Safety Improvement Intersection in prior years. Intersection was on the Fiscal Year 2005 Hazard Elimination List Section 152 and Fiscal Year 2006 STP-23 USC 148g lists. $280,725 was the estimated cost for existing improvements. The federal portion of the project was estimated at $251,539. |
Continue to Exhibit 7
- Memorandum, ACTION: Highway Safety Improvement Program Reporting "5 Percent Report", Title 23, Section 148 (c)(1)(D), Michael L. Halladay, FHWA, April 10 2006
- GUIDANCE HIGHWAY SAFETY IMPROVEMENT PROGRAM 23 U.S.C. 148 (c)(1)(D) "5 PERCENT REPORT" April 5, 2006 FHWA, page 2
- GUIDANCE HIGHWAY SAFETY IMPROVEMENT PROGRAM 23 U.S.C. 148 (c)(1)(D) "5 PERCENT REPORT" April 5, 2006 FHWA, page 7
Exhibit 7
State of Maryland
Identifying Candidate Safety Improvement Locations
To provide a safe highway
system to our constituents and to take advantage of securing available federal
safety funding, the Maryland State Highway Administration has developed procedures
for identifying Candidate Safety Improvement Locations on State maintained
highways. Listings of Candidate Safety Improvement Locations are developed
annually. Those locations having the highest accident experience and/or
accident rate are examined to determine the appropriate safety improvements.
Candidate Safety Improvement Locations are stratified into two categories:
Intersections (CSII) and Sections (CSIS). The criteria for the two
categories vary for obvious reasons. The following is an explanation of how
the criteria were developed for each grouping. The first grouping discussed
will be Candidate Safety Improvement Intersections.
Candidate Safety Improvement Intersections
Initially, it is necessary to determine the number of intersection related accidents on State designated highways for each of the 23 counties. The data collected is stratified by county because of the diversity in population and traffic volume characteristics existing in the various geographical locations throughout Maryland. This process is normally done by computer software and very simply involves selecting those accidents having been coded as being intersection related by the investigating police officer. The route designations we use in this selection have the following prefixes: MD, US, and in certain cases IS.
It is necessary to determine the number of intersections that are located on highways having the prefixes indicated above, for each county. This count of intersections does not include driveway intersections, interchanges, or ramp merges on fully controlled access highways. From the information gathered, the number of intersections per county and the number of intersection accidents per county, the average number of intersection accidents per intersection per county can be derived. For example, in Baltimore County there were 1,987 intersection related accidents and a total of 2,497 intersections yielding an average of 0.80 accidents per intersection in that county. This is done for each county in the State. The next step in the process is to determine what intersection accident frequency is significantly higher than the average for its respective county.
Determining the level of significance is done by using the Cumulative Poisson Distribution Table and selecting the appropriate proportion level desired. It has been our practice to use a poisson proportion level having a confidence interval of 1.000 as a first step in identifying those intersections experiencing an abnormally high number of accidents. To illustrate, if the average number of intersection accidents (0.80) in Baltimore County is applied to the Poisson Table using confidence interval of 1.000, an initial cut-off number of 5 intersection accidents for that county would be considered significant.
This initial cut-off number is considered the minimum cut-off number in the first selection of locations to be listed. In that some of our counties are very rural and experience very low traffic volumes, those counties will achieve a very low minimum cut-off number (less than 3 accidents). Since it would be less than wise to allocate funding for implementation of improvements to a location having less than 3 accidents, our minimum cut-off number for those counties experiencing this is set at 3 accidents. To insure that we are identifying only the most hazardous locations in each county, the criteria now becomes more stringent.
From a developed listing of locations meeting the minimum cut-off numbers, it is necessary to develop a new listing of locations to be considered Candidate Safety Improvement Intersections. Highlighting those locations experiencing an accident frequency two times the minimum cut-off number for its respective county refines the listing. For example, in Baltimore County the minimum cut-off number was determined to be 5 accidents, now to be considered for a Candidate Safety Improvement Location it has to have a minimum of 10 accidents. All of the locations meeting these county criteria are listed; traffic volume data for all legs approaching the intersections are collected and accident rates per million vehicles entering (rate/MVE) the intersections are calculated and applied to the list. The following equation is used to develop the accident rate per million vehicles entering.
The accident rate/MVE is used to further stratify those locations by relative hazard. Any location meeting a threshold level of 1 accident/MVE has been determined to be a Priority Candidate Safety Improvement Intersection. In doing this, the number of locations will be lower and the District staffs can adequately review the number of locations in their respective districts. Our intent is not to overburden the districts with more locations than they can physically handle.
Finally, a severity index was developed to be used as yet another tool to prioritize CSII listings. The severity index is used in determining the rank of locations that are otherwise equal in terms of accident rate. The severity index is also used to address those intersections that have met the accident frequency cutoff needed (not the rate/100MVE), but their severity of accidents warrant analysis to determine the need for safety countermeasures. The district staff is encouraged to review those locations having a severity index of 2.5 or greater.
The severity index is an accident rate that has been
weighted to adjust for accident severity. The technique used in calculating
the accident rate and severity index is based on information from the police
accident report form. The police accident report form includes the following
five severity classifications: fatality, incapacitating injury,
non-incapacitating injury, possible injury, and property damage only. These
assigned weighting factors are as follows:
| Severity | Weighting Factors |
|---|---|
| Fatality | 5 |
| Incapacitating Injury | 4 |
| Non-Incapacitating Injury | 3 |
| Possible Injury | 2 |
| Property damage only | 1 |
Example to determine accident severity (using figures from the previous example):
If 20 accidents were distributed as follows:
| Severity | Weighting Factor | Frequency | Weighted Average |
|---|---|---|---|
| Fatality | 5 | 1 | 5 |
| Incapacitating Injury | 4 | 2 | 8 |
| Non-Incapacitating Injury | 3 | 5 | 15 |
| Possible Injury | 2 | 7 | 14 |
| Property damage only | 1 | 5 | 5 |
| Total | 20 | 47 |
Candidate Safety Improvement Sections
The second area of discussion involves the identification of Candidate Safety Improvement Sections. This listing is totally computer generated. This process requires developing a listing of all non-intersection accidents throughout the State. From this listing and using the Highway Performance Monitoring System's traffic volume data, statewide accident rates per 100 million vehicle miles of travel are calculated and grouped by type of access control (number of lanes; divided/non-divided; full control, partial control, or no control of access; urban or rural designation). This information is used in the Critical Rate Formula further along in the process. At this point it is necessary to arrive at an accident frequency cut-off number to be used in eliminating those sections of highway having too low of an accident frequency and traffic volume. Our concern is not with those sections having 1 or 2 accidents and such a low traffic volume that the rate is high, but with those sections experiencing an accident frequency that could be most responsive to corrective engineering measures.
Annually, there are approximately 50,000 accidents on the State maintained system. The State of Maryland maintains approximately 5,000 miles of highways. This results in an average of approximately 10 accidents per mile. Since the intent is to identify the most hazardous sections with large clusters of accidents, our review of the accident experience encompasses 1/2-mile sliding scale sections having 10 or more accidents. The sliding scale program in essence slides every 100th of a mile. For example, if there is an accident at logmile 0.00 the segment will cover the area of 0.00 to 0.50. If the next accident is at 0.01, the 1/2-mile segment will slide from 0.01 to 0.51. This process will continue for each accident and generate our Candidate Safety Improvement Section (CSIS) file. This file is merged with the Highway Performance Monitoring System (HPMS) file, which incorporates the traffic volume data. Using both the CSIS file and the HPMS file, accident rates per 100 million vehicle miles of travel are computer generated for each 1/2 mile sliding scale segment having 10 or more accidents.
Statistical analyses are then applied to each candidate section to develop a final CSIS listing in each district. The statistical procedure used to identify candidate safety improvement sections is known as Donald A. Morin's Rate Quality Control Method (Upper Control Limit). This procedure determines an upper control limit accident rate using the following equation:
Where;
Rcu = the computed upper control limit accident rate (critical value) in 100
miles of travel.
Ra = the statewide average accident rate for specific category of highway.
K = a level of probability constant. This value is set at 1.645 and
provides a 95 percent probability level that the upper control limit could be
exceeded by chance variation in the observed accident rate.
M = vehicle miles of travel in the study section for the study period divided by
100,000,000.
The final criterion is to
compare the study section accident rate to the upper control limit accident
rate. When the difference between the study section rate and
upper control limit rate exceeds the upper control limit rate, the location is
considered a Priority (P) Candidate Safety Improvement Section. To
illustrate:
| Study Rate | Upper Control Rate | Difference | CSIS |
|---|---|---|---|
| 305 | 116 | 189 | P |
This procedure identifies those roadway segments that are determined to be most hazardous, and also provides a workable number of locations that can be addressed with the available District resources. The most important part of the analysis is the segregation of candidate safety improvement sections by number of lanes and the type of access control for each section so that the list contains only those sections that are experiencing significantly high accident rates when compared to highways with similar design characteristics.
