ROAD SAFETY AUDIT MAJOR HIGHWAY MEDIAN CROSS-OVER CRASHES I-95 ATTLEBORO/NORTH ATTLEBOROUGH

Transcription

1 ROAD SAFETY AUDIT MAJOR HIGHWAY MEDIAN CROSS-OVER CRASHES I-95 ATTLEBORO/NORTH ATTLEBOROUGH Prepared for Prepared by MS Transportation Systems, Inc. Framingham, Massachusetts June 2009

2 ROAD SAFETY AUDIT MAJOR HIGHWAY MEDIAN CROSS-OVER CRASHES I-95 ATTLEBORO/NORTH ATTLEBOROUGH June 2009 Prepared for Massachusetts Highway Department Prepared by MS Transportation Systems, Inc. 300 Howard Street P.O. Box 967 Framingham, Massachusetts (fax)

3 TABLE OF CONTENTS Page INTRODUCTION 1 RSA PROCESS 3 ANALYSIS 8 SUMMARY OF RSA FINDINGS/POTENTIAL ACTIONS 12 RECOMMENDATIONS 22 APPENDIX 28 I-95 Attleboro/North Attleborough Road Safety Audit Page i

4 Introduction Lane departure crashes are one of the primary fatal crash types in Massachusetts. The Commonwealth exceeds the national average for the proportion of fatal lane departure crashes and was designated a lead state in lane departure crashes by the American Association of State Highway and Transportation Officials (AASHTO). The Massachusetts Highway Department (MassHighway) conducted a study of the problem and found that during , lane departure crashes accounted for 25 percent of all injury crashes and nearly half, 46 percent, of all fatal crashes. As part of the effort in implementing the safety plan and specifically reducing lane departure crashes, the MassHighway is completing a Road Safety Audit (RSA) Review Project specifically focused on median crossing (or median cross-over) crashes on its major highways. Road safety audits are a formal safety performance examination on existing or future roadways by an independent audit team. These specific audits are being conducted in locations where cross-over experience has been or has the potential to be of concern and where the RSA team has judged that factors exist that could affect the safety risk. During the audit, the RSA team works to identify opportunities for enhancing safety and to recommend specific enhancements intended to reduce median cross-over crashes and improve the overall safety along the highway. A RSA was conducted for I-95 in Attleboro/North Attleborough as part of this project. Figure 1 indicates the corridor section under study between Interchange No. 3 and Interchange No. 5. This section had experienced a number of median related crashes, including several cross-median crashes. The purpose of this I-95 Attleboro/North Attleborough RSA is to examine potential safety risk factors and identify opportunities to enhance safety conditions on I-95 and address the identified factors. Recommendations contained in this report reflect the overall consent of the RSA team and do not necessarily reflect the official views of MassHighway. MS Transportation Systems, Inc. Page 1

5 95 North Attleborough Robert Toner Boulevard Interchange No Interchange No. 4 Attleboro South Avenue Interchange No. 3 Route 1 95 Project Location W N E I-95 Road Safety Audit Attleboro/North Attleborough, Massachusetts MS Transportation Systems, Inc. Framingham, Massachusetts S 1 : 25,000 FIGURE 1

6 RSA Process The general process outlined in the guideline 1 was essentially followed although with some minor variations incorporated in the overall procedure. These were due in part to the project location being a high speed, high volume section of an access controlled highway. With these characteristics, there are limited areas to safely stop and gather as a group along the section without potentially hindering traffic flow or the safety of the RSA team. Given the team size and general character with the corridor, the team members who visited the site prior to the team meeting did so either individually or in smaller groups. A video recording of a drive-thru in both directions was collected by the RSA consultant and used at the meeting to review conditions as a group. Background material and plans were transmitted to the RSA consultant to compile and review prior to the initial RSA team meeting. Crash and traffic volume data were transmitted to RSA team members prior to the meeting as well. Once the initial RSA team meeting was conducted, the RSA consultant used the input, completed the analysis and prepared a draft document for team members to review. Data including summary crash records for the period, three (3) detailed crash descriptions of cross-over crashes, and available record highway plans were obtained and reviewed by the RSA consultant. Following a review of the draft, the RSA report was finalized. RSA Team The following individuals participated in of the I-95 Attleboro/North Attleborough Road Safety Audit: Bill Travers, MassHighway District 5, Maint. Lisa Schletzbaum, MassHighway Safety Timothy White, FHWA Major Arthur McLaughlin, Troop H Paul Nelson, EOT Planning Trooper Daniel O Sullivan Paul Mission, SRPEDD Robert Gregory, MassHighway District 5 Traffic Bonnie Polin, MassHighway Safety Alolade Campbell, MassHighway District 5 Adam Rerchia, SRPEDD Shundreka Givan, FHWA Ashish Patel, MassHighway Design William J. Scully, MS Transportation Systems (RSA Consultant) RSA Meeting A meeting was held on May 15, 2008 at the MassHighway District 5 Office. At the meeting, the RSA consultant provided a brief overview of the RSA purpose, a summary 1 MS Transportation Systems, Inc., Road Safety Audits, Median Cross-Over Crashes, Audit Guidelines, Prepared for MassHighway, October MS Transportation Systems, Inc. Page 3

7 of the roadway section s characteristics and results of the review to date. The RSA team listed above was present at the meeting. The video record of I-95 taken while driving the corridor was viewed. During and following the video, there were further discussions related to the possible factors related to the cross-median crashes and possible solutions to prevent or reduce similar characteristics in the future. The RSA team provided input on background supporting data, the key items observed in the field and those items that were listed on the RSA Median Cross-Over Prompt List. Key items noted at the meeting included: A major concern in the section is the movement of vehicles from I-95 southbound to I-295 westbound. There are vehicle queues that occur on this ramp back onto the I-95 mainline during peak times. There are peak hour vehicle queues that occur on the Interchange 5 (Route 152) ramps planning agency attempted to program major improvements but the City was opposed. A signal is currently planned. Signage for Exits 4 and 5 in southbound direction can be confusing as signage for Exit 4 occurs prior to signage for Exit 5 as a result, may not be adequate. If a barrier is considered, the State Police pointed out the need for periodic turnarounds for authorized vehicles only. Following the RSA meeting, the RSA consultant compiled the information, for inclusion on the analysis and in the development of recommendations. Analysis Procedures As previously indicated, the RSA analysis followed the procedure described in Guideline with some variations and also took into consideration the methods published by the Federal Highway Administration 2 and those included in training materials 3. The basic tasks included: Obtaining and reviewing crash and other traffic characteristic data and available record plans. 2 Federal Highway Administration, FHWA Road Safety Audit Guidelines, Publication No. FHWA SA-06-06, Washington, D.C., Federal Highway Administration, Resource Center, Road Safety Audits Mini-Workshop, Jeffrey Shaw, PE, PTOE, presented to New England ITE Section, September 19, MS Transportation Systems, Inc. Page 4

8 Conducting site reconnaissance and collecting a current record of condition via photos and video, identify potential hazardous issues, and Identify and evaluate potential actions to address the noted issues. In assessing the issues identified by the RSA Team, the relative seriousness and potential risk relative to crash frequency and severity were determined. Using the guidelines of FHWA 4 as input and considering characteristics of this specific RSA, the relative frequency criteria and severity criteria were identified and are presented in Table 1 and Table 2, respectively. ESTIMATED TABLE 1 FREQUENCY RATING EXPECTED CRASH FREQUENCY (PER AUDIT ITEM) FREQUENCY RATING Exposure Probability high high 5 or more crashes per year Frequent medium high high medium 1 to 4 crashes per year Occasional medium medium low high high low Less that 1 crash per year, but Infrequent more than 1 crash every 5 years low medium medium low Less than 1 crash every 5 years Rare low low Typical Crashes Expected (per audit item) High-speed crashes; head on and rollover crashes Moderate-speed crashes; fixed object or off-road crashes Crashes involving medium to low speeds; lane changing or sideswipe crashes Crashes involving low to medium speeds; typical of rear-end or sideswipe crashes TABLE 2 SEVERITY RATING Expected Crash Severity Probable fatality or incapacitating injury Moderate to severe injury Minor to moderate injury Property damage only or minor injury Severity Rating Extreme High Moderate Low 4 Federal Highway Administration, Resource Center, Road Safety Audits Mini-Workshop, Jeffrey Shaw, PE, PTOE, presented to New England ITE Section, September 19, MS Transportation Systems, Inc. Page 5

9 Taking into consideration both frequency and severity, the relative risk of a particular audit item was rated. The risk ratings are shown in Table 3. For each safety issue identified, the potential seriousness of the issue as well as possible mitigation measures have been indicated. TABLE 3 CRASH RISK ASSESSMENT Frequency Rating Severity Rating Low Moderate High Extreme Frequent C D E F Occasional B C D E Infrequent A B C D Rare A A B C Crash Risk Ratings: A: minimal risk level D: significant risk level B: low risk level E: high risk level C: moderate risk level F: extreme risk level RSA Field Audit Audits were conducted by the team members prior to the RSA meeting. Key notes from the field work are as follows: The inside shoulder is about 3-4 feet in width with some off-pavement leveling area provided (another 1-3 feet +/-) depending on the specific location. South of the rest (parking) area (south of I-495) where resurfacing occurred within the past few years, rumble strips exist on the inside edge. The rumble strip is located approximately 6 inches outside the edge line. A rumble strip is also in place on the outside shoulder. The outside shoulder appears to be 10 feet in width (plans later confirmed the width). The median topography changes along the section. North of Route 152, it is relatively flat or slightly depressed. South of I-295 the median generally slopes down west to east with the southbound direction at a higher elevation than the northbound side. There may be drainage structures in the center of the median (plans to be checked), Speed limit signs indicate 65 mph with observed motorists traveling above speed limit possibly 5 to 10 mph above. There are imbedded reflectors in the pavement along lane lines but not in edge line. Reflective delineators are generally not present along the median, The current pavement markings and surface are in generally good condition. MS Transportation Systems, Inc. Page 6

10 A truck parking area exists in southbound direction about 1 mile south of I Southbound direction at the Attleboro/North Attleborough townline is on a horizontal curve with the outside lane on the outside of the curve giving some level of discomfort to driver. This was also noted in the northbound direction on the curve south of the rest area. Evidence of numerous median entries (around 6-8) based on visual tire tracks. Most of them were in the section north of Int. 5. Skid marks were also noted in certain areas one area was prior to overpass in the southbound direction before Interchange 4 where visibility is somewhat constrained. It was also noted that relatively new tree plantings (i.e. last few years) were in place north of Interchange 5. MS Transportation Systems, Inc. Page 7

11 Analysis I-95 in Attleboro/North Attleborough is a major interstate highway that provides northsouth movement in Eastern Massachusetts connecting with Rhode Island on the south to New Hampshire to the north. In the section under study, it consists of three (3) travels lanes per direction. The roadway also has a full (10 foot) outside shoulder and an inside shoulder in the range of 3 to 4 feet. Rumble strips have been installed on both the inside and outside shoulders. The alignment is varying but can be characterized as gentle. It was noted that the speed limits are posted at 65 miles per hour (mph). The median width measured inside edge line to inside edge line is approximately 100 feet. The unpaved portion of the median width through the section ranges from approximately 88 to 94 feet. While the length of the study section is approximately 5.7 miles, a review of the corridor shows that the length of the open median in this section is approximately 2.5 miles. The topography of the median varies through the study section. South of I- 295 near the reservoir, the median slopes down from the SB direction to the NB direction. North of I-295 and through Interchange No. 5 (Route 152), the median is flatter but with a depressed type design. There are also areas where the median is heavily treed that effectively blocks crossing the median in these areas. Figures 2 through 4 present photographs that depict the current conditions along the study section. Figure 2 - I-95 Southbound approaching the Route 152 Interchange (Interchange No. 5) MS Transportation Systems, Inc. Page 8

12 Figure 3 - I-95 Southbound lanes south of I-295 on-ramp. Figure 4 - I-95 in northbound direction north of Interchange No. 3. MS Transportation Systems, Inc. Page 9

13 A review of available safety data was completed as part of this RSA. The review of data included crash data for median related crashes reported for the years 2004 to 2007 and police narratives for the cross-median events. The summary table and spot map, which notes only the crashes that were median related, are included in the appendix. Key aspects noted in the data included the following: A total of 33 median related crashes were noted during this period. Of the total median related crashes, 3 or 9% were cross median crashes. There were no fatal crashes reported, however, approximately 50% of the total reviewed crashes resulted in personal injuries. Two-thirds of the reviewed crashes occurred in the southbound direction. Thirty-three percent (33%) of median related crashes occurred during the non-light period (i.e. 9PM-5AM) No one significant or predominant crash reason given though 12 were noted as failure to keep in proper lane. In reviewing the crash reports for the section under study, driver error and collision avoidance are more predominant than the other two reasons. The traffic volumes observed on I-95 in this section exceed 100,000 on an average weekday, north of I-295. Between I-295 and Interchange No. 3, the average daily volume was observed to be 88,000. Figure 5 depicts the hourly volume by direction in August 2007 north of Route 152. As shown, peak period flows in the peak direction exceed 4,000 vehicles per hour. Figure 6 illustrates the variation in flow on I-95 over the year. The data shows a consistently high volume month to month. Figure 5 - I-95 Directional Volume August 28, 2007 MS Transportation Systems, Inc. Page 10

14 I-95 Monthly Traffic Volume 140, ,000 Average Daily Volume 100,000 80,000 60,000 40,000 20,000 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month Figure 6 I-95 Monthly Traffic Volume North of I-295 In summary, the RSA I-95 in Attleboro/North Attleborough has identified a number of physical and operational characteristics as being potentially a contributing factors to increasing the risk of experiencing median related safety issues and the possibility of median crossings although each with varied levels of seriousness. The major ones include: Median is largely open, has a slope of 6:1 or flatter for the most part and was considered by the RSA team as highly crossable, High volumes (>88,000 to 100,000+) on average weekday depending on location, There is no barrier in median Queue backup onto I-95 SB from I-295. The next section will discuss these key issues and the potential actions to consider for addressing them. MS Transportation Systems, Inc. Page 11

15 Summary of RSA Findings/Potential Actions Based on the field review, the review of crash data and discussions among the RSA team members, the issues related to the safe operating conditions of the I-95 in the Attleboro/North Attleborough area were identified. There were a number of factors or issues of concern that were identified as potentially having an effect on the risk and these are listed in Table 4 along with the assigned risk rating. TABLE 4 SUMMARY OF FACTORS THAT POTENTIALLY AFFECT THE RISK OF SAFETY RELATED EVENTS Factor or Issue Significant amount of open median from north of Route 152 to south of I-295 with 6:1 slopes or flatter and considered as easily crossable Long queues in southbound direction from I-295 offramp extending several miles north Sight distance constraint exists in southbound direction north of the bridge over North Avenue Significant volume increase and weaving at the I-295 interchange Speed change lanes (acceleration, deceleration, weave areas) - markings and designation are minimal Adequacy motorist guidance southbound prior to Interchange Nos. 4 and 5 Motorist discomfort on outside lane of curve in open median area - northbound curve approaching rest area Motorist discomfort on outside lane of curve in open median area - southbound curve near town line Condition of non-paved area just off inside paved shoulder not smooth may affect recovery Condition of rumble strip and inside edge drop-off is significant in spots - could affect recovery Southbound rest area/truck area entry - merge Risk Rating D 1 E D D C B B B D C B 1 A risk rating of E would be assigned if based on total median entries. Based on the number of cross-median crashes a risk rating of D. Given the high traffic volume and the number of median entries, the open median factor could be assigned a higher risk factor. In other words, the operational and physical characteristics of the highway section under study is such that once a motorist makes a mistake or becomes errant and enters the median, there is a high probability that the motorist will cross the MS Transportation Systems, Inc. Page 12

16 median and enter the opposing direction of flow although recent reported crash data shows a small proportion of cross-median events. However, with the volumes in excess of 100,000 vehicles per day, this type of event becomes a greater possibility. Another significant factor noted by the RSA team concerns the I-95 southbound ramp to I-295 westbound movement. Combination of the volume, ramp geometry and merge design result in long vehicle queues and sluggish southbound movement that can typically extend back on I-95 for several miles. While this condition may result in nonmedian related incidents (i.e. rear end crash types instead), it may also result in increase lane-changing or quick, undesirable driver maneuvers that have the potential to result in median entries. Additionally, in the I-95/I-295 interchange area, there is a substantial increase in volumes as well as associated weaving and merging activity. Given this characteristic together with the queuing in the southbound direction, a relatively high risk rating was also unsigned to these factors. One sight distance issue was identified in the southbound direction as I-95 passes over North Avenue. While by itself, it is not a major sight distance constraint, but does become a greater factor if long queues and slow traffic exists approaching the I-95 offramp to I-295 westbound, then the constraint becomes more pronounced. During those times, motorists passing the overpass may come upon the queue too quickly resulting in quick moves to the left or stops that may force either motorist to maneuver left in order to avoid collision. Again, in a number of locations, once an errant motorist enters the median, there is a good possibility that a full crossing will occur. Consequently, a moderately high risk rating was assigned to this factor. The speed change lanes including acceleration lanes, deceleration lanes and the weave sections at I-295 appear to be short. In addition, guidance through the markings were less than optimum, which may have been due in part to less than standard lengths. This factor was assigned a risk rating of C. Signage in the southbound direction for Exits 4 and 5 were noted to be somewhat confusing that affects its adequacy. Specifically noted was that the Exit 4 overhead sign (2 mile notice) is placed just prior to the overhead guide sign for Exit 5 (1 mile notice). While noted that the confusion may contribute to some upstream lane changing if the motorist mixed the exits up, it was determined to have a small effect on cross median crashes. As a result, it was assigned a risk rating of B. In the southbound direction, there was a noticeable level of driver discomfort in the high speed (left most) travel lane on the outside of a curve leaning towards median. MS Transportation Systems, Inc. Page 13

17 There was also a similar, smaller amount, but noticeable of driver discomfort in the northbound direction on the curve approaching the rest area north of Interchange No. 5. This relates to travel in the high speed travel lane. Based on further review by MassHighway design staff who are participating on RSA team, it was determine that the inside (high speed) travel lane may have a cross slope towards the median slightly higher than desired. This condition in both locations contributes to the driver discomfort and potential median entries. This factor in both locations was assigned a B. The conditions of the rumble strip, pavement edge and surface of the off-pavement surface were all noted as being less than desirable. While the rumble strip addresses driver inattentiveness or driver fatigue, the edge drop off and off-pavement surface condition affects the recovery of the errant motorists. The condition of the off-pavement area was rated a D and the edge drop off factor and rumble strip were assigned a C. The last factor in the table relates to the rest/parking area in the southbound direction. The factor noted relates specifically to the parking area exit/merge area on I-95 with some open median in that section. Following further discussion of crash experience in that particular area, it was assigned a risk rating of B. Suggested actions in this program identified are intended to reduce or eliminate crossmedian crashes, injuries and fatalities related to them. In addition, the actions may serve to reduce the severity of all the crashes. The following paragraphs include discussion pertaining to the issues and the potential actions to consider for implement. Given that a primary objective of this RSA was in relation to cross median crashes, the evaluation of a median barrier was an initial action studied. The following section describes the evaluation of the median barrier. Consideration of a Median Barrier One of the more significant actions to be considered is to install median barriers in the current open areas. A barrier can be considered when there is a higher than desirable chance or a greater risk for median cross-over crashes to occur and that have or could result in fatalities and/or a high proportion of injury related crashes. In addition, a barrier could be considered when the consequences or severity of a crash are worse than if the barrier were in place. Factors that generally come into play in deciding on whether a median should be installed involve the following: High volumes and speeds Truck volumes and mix MS Transportation Systems, Inc. Page 14

18 Median Width: 100 feet ADT - 88, , AVERAGE DAILY TRAFFIC (thousands) BARRIER RECOMMENDED BARRIER CONSIDERED BARRIER OPTIONAL MEDIAN WIDTH (feet) Source: AASHTO Roadside Design Guide, Chapter 6, Updated 2006 Median Barrier Warrant Evaluation I-95 Road Safety Audit Attleboro/North Attleborough, Massachusetts MS Transportation Systems, Inc. Framingham, Massachusetts FIGURE 7

19 Narrow median History of cross-median crashes High risk of catastrophic event These items have been reviewed relative to the I-95 section under study. Figure 7 presents a review of the corridor in relation to the median warrant criteria presented in the AASHTO RDG 5. As can be seen in the diagram, with the median (as measured from edge line to edge line) is approximately 100 feet and a volume of over 100,000 vehicles on an average day north of I-295, the intersection of the two items is in the area of the chart where a barrier is optional. South of I-295, the daily volume is approximately 88,000, the criteria would still suggest optional. In addition to the chart and related warrant criteria, which is a guideline, further consideration was given to the following: The high volume presents a likelihood of greater number of errant vehicles entering the median, A relatively high number of median entries (33) over the four (4) year period and the median appears to be very crossable. The elevation difference between the southbound and northbound directions south of I-295 shorten the crossing. There was a general discomfort felt by many RSA team members when driving the fast (inside) lane. Consequently, based on the analysis of the data, the field drive-thru and discussion of the conditions by the RSA team members, it is suggested that a median barrier be installed in the section of the route that are currently open and crossable. Figure 8 shows the approximate locations of the proposed new barrier location. This will represent approximately 2.6 miles of barrier to be installed. The selection of the barrier is discussed in the next section. A. Barrier Selection There are a number of barrier types that can be considered in addressing the median cross-over crashes. These include the following: Weak post W-Beam Box Beam Generic Low Tension Cable High Tension Cable Barrier Strong post W-Beam Thrie Beam Concrete (Jersey) 5 American Association of State Highway and Transportation Officials, Roadside Design Guide, Washington, D.C., 2002, Chapter 6 Update MS Transportation Systems, Inc. Page 16

20 95 Location 4 4,800 ft. Interchange No. 5 Location 3 2,550 ft. Interchange No Location 2 2,250 ft. Location 1 4,000 ft. Interchange No. 3 - approximate locations of new barrier - interchanges Note: Total approximate barrier length is 2.6 miles NOT TO SCALE Proposed Locations for New Median Barrier I-95 Road Safety Audit Attleboro/North Attleborough, Massachusetts MS Transportation Systems, Inc. Framingham, Massachusetts FIGURE 8

21 In deciding on the type of barrier, recommended guidelines in selection are included in Table 5 taken from the AASHTO Roadside Design Guide 6. TABLE 5 CRITERIA FOR BARRIER SELECTION Criteria Comments 1. Performance Capability Barrier must be structurally able to contain and redirect design vehicle. 2. Deflection Expected deflection of barrier should not exceed available deflection distance. 3. Site Conditions Slope approaching the barrier and distance from traveled way may preclude use of some barrier types. 4. Compatibility Barrier must be compatible with planned end anchor and capable of transitioning to other barrier systems (such as bridge railings). 5. Cost Standard barrier systems are relatively consistent in cost, but high-performance railings can cost significantly more. 6. Maintenance A. Routine Few systems require a significant amount of routine maintenance. B. Collision Generally, flexible or semi-rigid systems require significantly more maintenance after a collision than rigid or high-performance railings. C. Material Storage The fewer different systems used, the fewer inventory items/storage space required. D. Simplicity Simpler designs, besides costing less, are more likely to be reconstructed properly by field personnel. 7. Aesthetics Occasionally, barrier aesthetics are an important consideration in selection. 8. Field Experience The performance and maintenance requirements of existing systems should be monitored to identify problems that could be lessened or eliminated by using a difference barrier type. Source: AASHTO, Roadside Design Guide, 2002, Chapter 5 Roadside Barriers. From a cost and aesthetic perspective, the cable (flexible) barrier has its advantages over the various guardrail systems or concrete barrier. The median slope and/or recovery area also affects the use and placement of any barrier including guardrail. With regard to the cable barrier, the RSA team has discussed two primary cable alternatives noted below. In addition to the cable barrier systems, team members also suggested that guardrail be considered in the evaluation. The alternative types of guardrail were reviewed for potential application on this route. 6 American Association of State Highway and Transportation Officials, Roadside Design Guide, Washington, D.C., 2002, Chapter 6 Update MS Transportation Systems, Inc. Page 18

22 Considerations included the volume of traffic, relative amount of truck traffic and travel speeds. Based on these, the most applicable types of guardrail for this route include the W-beam with strong post or the strong post thrie-beam. These rails are appropriate for high speed highways and high volumes with a relatively high proportion of truck traffic. Costs for each are similar. The weak post W-beam and box beam can be eliminated due to the slope and type of highway. The concrete barrier would generally be applicable in urban sections with limited median widths available. As a result, the median barrier options that are valid for consideration for I-95 in this section are the cable barrier and strong post guard rail. Maintenance issues are also an important consideration in decisions regarding median barrier installations. The maintenance issues that are of concern include: Barrier hits per mile Frequency of hits Cost recovery Cable downtime Repair effect on traffic Maintaining tension Final selection of the barrier type should be based on the costs, the ability to maintain a recovery zone, likely maintenance or repair requirements, and compatibility with future planned widening. The key points of the cable barrier or guardrail are summarized below. Cable Barrier While the low tension generic cable system has been in existence for more than 50 years, most of the recent cable system research and installation is focused on the high tension systems. There are currently six (6) manufacturers with systems approved by the Federal Highway Administration (FHWA) for use under certain conditions. There are 3-rope or 4-rope cable systems as shown in the following two photographs. This barrier type can be installed on slopes of 6:1 or flatter with little constraint on placement. There are certain systems (i.e. Brifen and Gibraltor 4 rope) that have been approved for slopes as steep as 4:1. In addition to the lower installation costs, the cable barrier can usually be located sufficiently away from the pavement area to allow for recovery zone and a minimal number of hits. MS Transportation Systems, Inc. Page 19

23 3 Cable CASS System on Route Rope Brifen System on I-495 Guardrail In general, guardrail could be placed toward or in the center of the median where slopes are 10:1 or flatter (i.e. I-93 Braintree) as well as at the edge of a steep slope or where minimal recovery zones exist. With the guardrail placed within several feet of the pavement edge, a clear zone (or recovery area) would be eliminated at least on one side of the median if guardrail is applied on only one side of the median. Per mile costs of the basic types of median barrier treatment to be considered for this route are summarized in Table 6. Shown in the table are estimated per mile costs of installing a cable barrier, a double faced W-beam guardrail and a double faced thriebeam guardrail. As can be seen, the cable barrier is expected to be the lower cost option. It should be noted that the estimated costs for the cable barrier are largely based on recent limited applications in the Commonwealth. Construction costs for cable installation could be substantially lower based on experience in other parts of the country (examples in Appendix). The W-beam rail is a lower cost option compared to the thriebeam, however, there is slightly greater deflection with the W-beam. TABLE 6 COMPARISON PER MILE COSTS Cable vs. Guardrail Costs/Mile Cable $144,000 W-beam $171,000 Thrie beam $213,000 MS Transportation Systems, Inc. Page 20

24 Based on the above costs, the installation of cable barrier in the identified sections is estimated to cost approximately $374,400 while use of thrie-beam would result in a cost of approximately $553,800. The next section outlines all of the RSA team recommendations including the median barrier. MS Transportation Systems, Inc. Page 21

25 Recommendations As a result of the RSA analysis and team input, a set of recommendations have been identified and are summarized in Table 7. It was the overall consensus of the I-95 Attleboro/North Attleborough RSA team that due to the high volumes of traffic, the traffic characteristics in the area of Interchange 4 and between Interchange Nos. 4 and 5 in the southbound direction that can influence lane changing behavior, a series of suggestions were appropriate in order to reduce the risk of median entry and cross median crashes in the study sections. These actions are intended to eliminate the chance of crossmedian crashes as well as reduce the severity of all crashes and improve the overall safety condition of this section of I-95 in Attleboro/North Attleborough. Identified in the table in addition to the risk factor and recommended action are the estimated costs and potential timeframe (i.e. short (0-1 year), medium (1-3 years) and long (>3 years). A major action suggested is the installation of a median barrier in several open sections. For several reasons including costs, maintaining a recovery area and aesthetics, it is recommended that a cable barrier be installed. Figure 8 previously illustrated the approximate locations of the new installation that totals about 2.6 miles in 4 different sections. Construction decisions can be made during design relative to retaining the existing small groves of trees or the recently planted trees in the northern area of the study section. Based on a unit cost of $144,000 per mile, installing the cable barrier is estimated at $374,400. Another major area of improvement suggested by the RSA team relates to the guidance and traffic design of the I-295 (Interchange No. 4) interchange with I-95. In an effort to reduce the peak period vehicle queuing back onto I-95, a new striping plan for the southbound section from the I-95 northbound on-ramp is suggested to smooth the I- 295 merging. It is also recommended that better advance warning caution signs be installed approaching the I-295 interchange in both directions. Figure 9 illustrates in concept the proposed marking plan while Figure 10 illustrates potential sign legends. Figure 11 provides information relative to the placement of the signs. The location of SIGN C would be two miles prior to Exit 4 (I-295) while SIGN B would be located at Station (Plan Reference Attleboro-Canton I-95 Project #601166). Also in the southbound direction, it is recommended that a queue detection system be put in place on the I-95 southbound on-ramp to I-295 with variable message sign (VMS) placed at approximately the North Avenue overpass. While this may be a longer tern option, this is intended to address the visibility constraint if long ramp queues and slow morning southbound traffic exists south of the overpass. MS Transportation Systems, Inc. Page 22

26 TABLE 7 SUMMARY OF RECOMMENDATIONS Risk Factor Significant amount of open median from north of Route 152 to south of I-295 with 6:1 slopes or flatter and considered as easily crossable Long queues in southbound direction from I-295 off-ramp extending several miles north Sight distance constraint exists in southbound direction north of the bridge over North Avenue Significant volume increase and weaving at the I-295 interchange Speed change lanes (acceleration, deceleration, weave areas) - markings and designation are minimal Adequate motorist guidance southbound prior to Interchange Nos. 4 and 5 Motorist discomfort on outside lane of curve in open median area - northbound curve approaching rest area Motorist discomfort on outside lane of curve in open median area - southbound curve near townline Risk Rating Recommended Action Estimated Cost (order of magnitude) Estimated Timeframe D 1 Install cable barrier $374,400 medium term E D D Modify pavement markings to indicate single lane on I-295 from I-95 NB on-ramp Widen I-295 SB on ramp to 2 lanes Install warning signage in SB direction north of I-295 Install static warning sign Install electronic queue detector VMS warning sign in SB direction Add safety warning signs Increase enforcement $5,000 TBD $20,000 $10,000 TBD $10,000 TBD C improve markings TBD (est. low cost) B B B combine 1 st sign for Exits 5 and 4 Improve delineation with posts, signage or markers Check superelevation Adjust during resurfacing Improve delineation with posts, signage or markers Check superelevation Adjust during resurfacing short term long term short term short term long term short term short term short term $20,000 short term $3,000 - short term short term medium to long term - short term short term medium to long term Condition of non-paved area just off inside paved shoulder not smooth may affect recovery Condition of rumble strip and inside edge drop-off is significant in spots could affect recovery Southbound rest area/truck area entry merge D C Provide more fill and regrade 1 A risk rating of E would be assigned if based on total median entries B Consider installing the angled safety edge Improve signage for merge and Yield control TBD (anticipate low cost) Estimated at 1 to 2 percent of total resurfacing short term long term as part of resurfacing $2,000 Short term MS Transportation Systems, Inc. Page 23

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28 MERGING TRAFFIC 1100 FEET SIGN A EXPECT OFF-RAMP BACKUPS AT EXIT 4 EXPECT STOPPED TRAFFIC NEXT 2 MILES SIGN B SIGN C CONCEPTUAL ONLY - NOT TO SCALE Potential Sign Legends I-95 Road Safety Audit Attleborough, Massachusetts MS Transportation Systems, Inc. Framingham, Massachusetts Figure 10

29 95 c 5 B A 3 3 LEGEND A B c - (see Figure 8) - place northbound approx. Sta (see Figure 8) - place southbound approx. Sta (see Figure 8) - place southbound approx. Sta interchanges NOT TO SCALE Potential Major Sign Placement I-95 Road Safety Audit Attleborough, Massachusetts MS Transportation Systems, Inc. Framingham, Massachusetts FIGURE 11

30 Pavement markings at the interchanges could be improved. The use of dotted extension lines enhance motorist guidance. The current MUTCD depicts dotted lines as an option for deceleration lanes and weave sections between on- and off-ramps. The 2009 updated MUTCD is anticipated to include dotted extension lines for acceleration lanes as well. Examples of the markings are included in the Appendix. Addressing the driver discomfort issue and cross-slope of the inside travel lane in the noted southbound and northbound directions will require adjustments in future resurfacing projects following additional engineering analysis. Resurfacing will likely be medium to long term projects. Short term actions would include new delineator posts along the median and/or warning (guidance) signs. A short term action would also be to check the cross slope (superelevation). Other safety actions suggested for I-95 include using the flexible delineator posts along the inside edge of the highway, regrading portions of the unpaved median including addressing the edge drop off where its significant, improved warning and control signs at the southbound rest area and increase the level of enforcement of speeds and inappropriate lane changing behavior. MS Transportation Systems, Inc. Page 27

31 Appendix RSA Meeting Agenda RSA Attendees List Median Crash Diagram Crash Data Traffic Volume Data Samples of Lane Markings MS Transportation Systems, Inc. Page 28

32 Road Safety Audit N. Attleborough/Attleboro Interstate 95 Meeting Location: MassHighway District 5 Office 1000 County Street, Taunton Thursday, May 15, :00 AM 12:00 PM Type of meeting: Attendees: Please bring: Cross Median Road Safety Audit Invited Participants to Comprise a Multidisciplinary Team Thoughts and Enthusiasm!! 10:00 AM Welcome and Introductions 10:15 AM Introduction to Road Safety Audits and Cross Median Crashes 10:30 AM Review of Site Specific Material Crash & Volume Summaries provided in advance Existing Geometries and Conditions Video and Images 11:00 AM Completion of RSA Identification of Safety Concerns using RSA Prompt List as a guide Identification of Possible Countermeasures 12:00 PM Adjourn for the Day but the RSA has not ended Instructions for Participants: Before attending the RSA on May 15th participants are encouraged to drive Interstate 95 in N. Attleborough and Attleboro (Interchanges 3-6) and complete/consider elements on the RSA Prompt List with a focus on safety factors affecting cross median crashes. All participants will be actively involved in the process throughout. Participants are encouraged to come with thoughts and ideas, but are reminded that the synergy that develops and respect for others opinions are key elements to the success of the overall RSA process. After the initial RSA meeting, participants will be asked to comment and respond to the document materials to assure it is reflective of the RSA completed by the multidisciplinary team.

33 ROAD SAFETY AUDIT MEETING I-95 - Mya 15, 2008 MassHighway District 5 Offices, Attleboro/North Attleborough MA Attendance List Name Agency/Dept. William Scully MS Transportation Systems bscullyjr@mac.com William Travers MHD District 5 Maint. Bill.Travers@mhd.state.ma.us Timothy White FHWA Timothy.A.White@fhwa.dot.gov Paul Nelson EOTP Paul Mission SRPEDD pmission@srpedd.org Bonnie Polin MHD Safety Bonnie.Polin@state.ma.us Adam Rerchia SRPEDD arerchia@srpedd.org Ashish Patel MHD Design ashish.patel@mhd.state.ma.us Lisa Schletzbaum MHD Safety lisa.schletzbaum@mhd.state.ma.us Major Arthur McLaughlin Troop H Trooper Daniel O'Sullivan Troop H daniel.osullivan@pol.state.ma.us Robert Gregory MHD District 5 Traffic robert.gregory@mhd.state.ma.us Alolade Campbell MHD District 5 Alolade.Campbell@mhd.state.ma.us Shundreka Givan FHWA Shundreka.Givan@fhwa.dot.gov MS Transportation Systems, Inc.

34 LANDRY AVENUE SMITH STREET NORTH ATTLEBOROUGH I-95 Interchange Median Crashes LANDRY AVENUE 95 1 FRANCIS KELLY BOULEVARD ± ELM STREET Crash IDs between 5-13 JOHN L DIETSCH BOULEVARD 5 ") Crash IDs between NORTH AVENUE NORTH MAIN STREET ATTLEBORO MOUNT HOPE STREET ") Legend Type of Median Crash * HOLDEN STREET Major Roads Cross Median, Non-Fatal Crash Interstate Median, Fatal Crash Principal Arterial Median, Non-Fatal Crash Minor Arterial Municipal Boundary Collector Local WEST STREET * 2007 crash file has not yet been closed Miles

35 MASSACHUSETTS HIGHWAY SAFETY DIVISION CRASH SUMMARY ROADWAY: STUDY PERIOD: I-95 CITY: ATTLEBORO AND NORTH ATTLEBOROUGH 1/1/2004 TO 12/31/2007 LOCATION: BETWEEN EXITS #4 AND #6 NO. CRASH NUMBER TRAVEL LIGHT WEATHER ROAD REASON FOR VEHICLE MEDIAN OR CROSS DRIVER CONTRIBUTING CRASH LANES CONDITION CONDITION SURFACE RUNNING OFF ROAD LEFT MOVEMENT MEDIAN CRASHES CAUSE SEVERITY NB Dark - Not Lighted Clear Dry Lost control of vehicle and overturned Travel Lane to Trees in the Median Median Failure to keep in proper lane Non-Fatal Injury NB Dark - Not Lighted Clear Dry Vehicle struck another parked vehicle in the breakdown lane Travel Lane to Median Median Inattention Non-Fatal Injury SB Dark - Not Lighted Clear Dry Vehicle strike another vehicle in the rear, spun out and overturned Travel Lane to Median Median Exceeded Speed Limit and Alcohol Non-Fatal Injury SB Daylight Clear Dry Vehicle right rear tire blew out and overturned Travel Lane to Median Median No Improper Driving Property Damage Only SB Daylight Clear Dry Lost control of vehicle and traveled off the road Travel Lane to Trees in the Median Median Failure to keep in proper lane Property Damage Only SB Dark - Not Lighted Clear Dry Lost control of vehicle and overturned Travel Lane to Median Median Failure to keep in proper lane Non-Fatal Injury SB Dark - Not Lighted Clear Dry Vehicle changed lanes to an already occupied lane and strike the side of another vehicle Travel Lane to Trees in the Median Median Failure to keep in proper lane Property Damage Only SB Daylight Clear Dry Vehicles distracted due to box truck stuck in the median Travel Lane to Median Median Distracted Property Damage Only SB Daylight Clear Dry Vehicle load shifted and caused vehicle to overturn Travel Lane to Median Median No Improper Driving Non-Fatal Injury SB Dark - Not Lighted Cloudy Dry Lost control of vehicle and struck guardrail Travel Lane to Median Guardrail to Middle Median Median Failure to keep in proper lane Non-Fatal Injury SB Daylight Clear Dry Lost control of vehicle and swerved off the road S/B Travel Lanes to N/B Travel Lanes Cross Median Swerving in roadway Non-Fatal Injury SB Daylight Rain Dry Vehicle changed lanes to an already occupied lane and strike the left side of another vehicle Travel Lane to Median Median Failure to keep in proper lane Property Damage Only SB Daylight Cloudy Dry Vehicle changed lanes to an already occupied lane and overcorrected S/B Travel Lanes to N/B Travel Lanes Cross Median Over-correcting/Over-steering Property Damage Only SB Dark - Not Lighted Clear Dry Fallen asleep and vehicle drifted into median and overturned Travel Lane to Median Median Fatigued/Asleep Property Damage Only NB Daylight Clear Dry Vehicle intentionally forced another vehicle into the guardrail Travel Lane to Median Guardrail Median Operating vehicle in reckless manner Non-Fatal Injury NB Dark - Not Lighted Clear Dry Vehicle was cut-off by unknown vehicle Travel Lane to Median Jersey Barrier Median Swerving or avoiding due to vehicle in roadway Property Damage Only NB Dark - Not Lighted Clear Dry Vehicle was cut-off by unknown vehicle Travel Lane to Median Barrier Median Swerving or avoiding due to vehicle in roadway Property Damage Only NB Dark - Not Lighted Clear Dry Vehicle rear ended another vehicle and traveled off to the median Travel Lane to Median Median Followed too closely Non-Fatal Injury NB Dark - Not Lighted Clear Dry Vehicle hit another vehicle in right rear, lost control and struck the guardrail Travel Lane to Median Guardrail Median Alcohol Property Damage Only NB Daylight Rain Wet Vehicle rear ended another vehicle and struck the guardrail Travel Lane to Median Guardrail to Travel Lane Median Failure to keep in proper lane Non-Fatal Injury NB Daylight Snow Ice Lost control of vehicle in snow storm and bounced off guardrail hitting other vehicles Travel Lane to Median Guardrail to Travel Lane Median Swerving due to slippery surface in roadway Non-Fatal Injury NB Daylight Sleet, Hail, Freezing Rain Slush Lost control of vehicle in snowy condition, struck guardrail and spun around hitting other vehicles Travel Lane to Median Guardrail to Travel Lane Median Driving too fast for condition Non-Fatal Injury SB Daylight Clear Wet Lost control of vehicle and hit concrete bridge support pillars Travel Lane to Median Bridge Support Pillars Median Failure to keep in proper lane Property Damage Only SB Daylight Clear Dry Vehicle rear ended another vehicle and traveled off to the median Travel Lane to Median Median Followed too closely Non-Fatal Injury SB Daylight Clear Dry Vehicle swerved into travel lane and hit another vehicle Travel Lane to Median Median Failure to keep in proper lane Property Damage Only SB Daylight Clear Dry Vehicle steering locked up and caused vehicle to overturned Travel Lane to Median Median Operating defective equipment Property Damage Only SB Daylight Clear Dry Vehicle rear tire blew out and overturned Travel Lane to Median Median No Improper Driving Non-Fatal Injury SB Daylight Not Reported Dry Vehicle changed lanes to an already occupied lane and strike the side of another vehicle Travel Lane to Trees in the Median Median Failure to keep in proper lane Property Damage Only SB Daylight Clear Dry Vehicle changed lanes to an already occupied lane and strike the left side of another vehicle Travel Lane to Median Guardrail Median Failure to keep in proper lane Non-Fatal Injury SB Daylight Clear Dry Vehicle was cut-off by unknown vehicle and overturned Travel Lane to Median Median Operating vehicle in reckless manner Property Damage Only NB Daylight Cloudy Dry Vehicle changed lanes to an already occupied lane and caused another vehicle to strike guardrail Travel Lane to Right Guardrail to Median Median Swerving or avoiding due to vehicle in roadway Not Reported SB Daylight Clear Dry Vehicle rear ended another vehicle and traveled off to the median S/B Travel Lanes to N/B Right Guardrail Cross Median Exceeded Speed Limit Non-Fatal Injury NB Daylight Clear Dry Vehicle swerved into travel lane and hit other vehicle Travel Lane to Right Guardrail to Median Guardrail to Travel Lane Median Failure to keep in proper lane Property Damage Only TOTAL NO. LIGHT CONDITION WEATHER CONDITION DAYLIGHT DARK-NOT LIGHTED CLEAR CLOUDY RAIN SNOW SLEET, HAIL, FREEZING RAIN NOT REPORTED % 67% 33% 76% 9% 6% 3% 3% 3% ROAD SURFACE MEDIAN OR CROSS MEDIAN CRASH SEVERITY DRY WET ICE SLUSH MEDIAN CROSS MEDIAN PROPERTY DAMAGE ONLY NON-FATAL INJURY NOT REPORTED % 6% 3% 3% 91% 9% 48% 48% 3% DRIVER CONTRIBUTING CAUSE NO IMPROPER EXCEEDED SPEED EXCEEDED SPEED ALCOHOL DRIVING TOO FAST FOLLOWED TOO FAILURE TO KEEP IN PROPER LANE SWERVING OR AVOIDING DUE TO VEHICLE IN ROADWAY SWERVING IN DRIVING LIMIT LIMIT & ALCOHOL FOR CONDITION CLOSELY ROADWAY % 3% 3% 3% 3% 6% 36% 9% 3% DRIVER CONTRIBUTING CAUSE SWERVING DUE TO SLIPPERY OPERATING VEHICLE OVER-CORRECTING/ INATTENTION DISTRACTED FATIGUED/ SURFACE IN ROADWAY IN RECKLESS MANNER OVER-STEERING ASLEEP OPERATING DEFECTIVE EQUIPMENT % 6% 3% 3% 3% 3% 3% 2007 CRASH INFORMATION ARE NOT COMPLETE CRASH SUMMARY IS BASED ON CRASH REPORTS WITH STATE POLICE NARRATIVES