ROAD SAFETY AUDIT
TRUCK ROLLOVER CRASHES
I-95/I-495 Interchange
Town of Foxborough Town of Mansfield
December 28, 2012
Prepared For:
MassDOT Highway Division
Prepared By:
BETA Group, Inc.
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Table of Contents
Project Data .................................................................................................................................1
Background .................................................................................................................................2
Project Description .....................................................................................................................2
Audit Observations .....................................................................................................................6
Potential Safety Enhancements ...............................................................................................10
Summary of Road Safety Audit...............................................................................................13
List of Appendices
Appendix A.
Appendix B.
Appendix C.
Appendix D.
RSA Meeting Agenda
RSA Audit Team Contact List
Crash Diagram
Traffic Volume Data
List of Figures
Figure 1.
Location Map ......................................................................................................................... 3
List of Tables
Table 1.
Table 2.
Table 3.
Table 4.
Participating Audit Team Members ....................................................................................... 1
Ramp Traffic Data.................................................................................................................. 5
Estimated Time Frame and Costs Breakdown ..................................................................... 10
Potential Safety Enhancement Summary ............................................................................. 14
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Project Data
A Road Safety Audit for Truck Rollover Crashes at the interchange of Interstate 95 (I-95) and Interstate
495 (I-495) in Foxborough and Mansfield was held on November 28, 2012 at the Foxborough Fire Station
in Foxborough, MA. As indicated in Table 1, the audit team consisted of representatives from Federal,
State, Regional and Local agencies and included a cross-section of engineering, planning, operations,
safety, enforcement and emergency response expertise.
Table 1. Participating Audit Team Members
Audit Team Member
Agency/Affiliation
Bonnie Polin
MassDOT Highway Division – Safety
Corey O’Connor
MassDOT Highway Division – Safety
Neil Boudreau
MassDOT Highway Division – State Traffic Engineer
Steve Timmins
MassDOT Highway Division – Traffic
Edward Feeney
MassDOT Highway Division – District 5 Traffic Operations
Barbara LaChance
MassDOT Highway Division – District 5 Traffic Operations
Thomas Burnett
MassDOT Highway Division – Safety Section
Matthew Poirier
FMCSA – USDOT
Jeff Stuart
Massachusetts State Police – Foxboro
Paul D’Amore
Massachusetts State Police – Troop H HQ
Roger Hatfield
Foxborough Fire Dept – Chief
Steve Bagley
Foxborough Fire Dept. – Deputy Chief
Robin Riessman
UMass Safe
Neal Boldrighini
Mansfield Fire Dept. – Chief
Greg Lucas
BETA Group, Inc.
Justin Curewitz
BETA Group, Inc.
Page 1
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Background
The Federal Highway Administration defines a Road Safety Audit (RSA) as the formal safety
examination of an existing or future road or intersection by an independent, multidisciplinary team. The
purpose of an RSA is to identify potential safety issues and possible opportunities for safety
improvements considering all roadway users. A Road Safety Audit was scheduled for the I-95 and I-495
interchange because it has been identified as a high crash location for truck crashes including rollovers.
The interchange is a full cloverleaf and the audit included all eight ramps that form the interchange
between the two highways. The purpose of the RSA is to identify both short and long term safety
improvements that can be implemented to reduce crashes at the interchange.
Project Description
The interchange of Interstates 95 and 495, shown in Figure 1, is bisected by the town line separating
Foxborough and Mansfield. The interchange is a full cloverleaf interchange with separate ramps for each
connection in each direction between the two highways. The ramps from I-95 Northbound to I-495
Northbound, I-95 Southbound to I-495 Southbound, I-495 Northbound to I-95 Southbound and I-495
Southbound to I-95 Northbound are loop ramps, while the ramps from I-95 Northbound to I-495
Southbound, I-95 Southbound to I-495 Northbound, I-495 Northbound to I-95 Northbound and I-495
Southbound to I-95 Southbound are typically composed of an entry curve to the right, a short tangent
segment, a curve to the left, another short tangent segment and a final curve to the right to merge onto the
mainline.
I-495 is approximately 120 miles in length and serves as the outer loop around the greater Boston area,
extending essentially from Cape Cod to the New Hampshire border. I-495 is a north-south route but
follows more of an east-west alignment at its interchange with I-95, as can be seen in Figure 1. Both
highways are highly desirable corridors for both local and regional truck travel.
Truck crash data for the interchange were provided by the Massachusetts State Police from 2008 to the
present. The crash summary diagram included in the Appendix shows 19 total crashes on the ramps or at
the entry or exit to the ramps between I-95 and I-495. One additional truck rollover crash occurred in the
week following the audit on the ramp from I-95 Northbound to I-495 Southbound. A discussion of crash
details by ramp follows.
I-95 Northbound to I-495 Southbound
This ramp experienced five crashes: a rear-end crash; a merge related crash; a crossover crash; and two
rollover crashes. The rear-end crash involved a truck rear-ending a passenger car and occurred at the entry
to the ramp. The merge related crash also occurred at the entry to the ramp and involved a vehicle
beginning to exit then merging back into the I-95 travel lane and colliding with a truck. The crossover
crash involved a car on the loop ramp from I-495 Southbound to I-95 Northbound which left the ramp,
crossed over to the I-95 Northbound to I-495 Southbound ramp and struck a truck.
Page 2
IN
TE
RS
TA
TE
INT
ER
ST
AT
E
49
5
49
5
NO
R
TE
IN
RT
H
SO
UT
H
R
TE
IN
GH
OU
R
O
XB
FO
F
NS
MA
D
IEL
R
TE
IN
R
TE
IN
E
AT
ST
95
N
O
E
AT
ST
95
E
AT
ST
95
N
O
E
AT
ST
95
TH
U
SO
TH
R
INT
TH
U
SO
INT
ER
ST
AT
E
ER
ST
AT
E
49
5
49
5
SO
UT
H
TH
R
LEGEND
TOWN LINE
Road Safety Audit
I-95/I-495 Interchange
Figure 1
Foxborough/Mansfield, MA
Location Map
NO
RT
H
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
The two truck rollover crashes, including the most recent crash which is not
shown on the diagram, occurred near the end of the ramp at the merge to I-495
Southbound. Rollover crashes occur when a load shift causes the trailer wheels
to lift. Momentum carries the trailer over and brings the truck cab with it. This
shift occurs due to excessive speed; either the driver is carrying too much speed
through the ramp, or the driver is accelerating at the end of the ramp in
anticipation of merging into traffic on I-495. A single W1-13 Truck Rollover
sign with a 25 MPH advisory plaque is located on the left side at the entrance to
the ramp, but no additional signs are provided at the curve where the two rollover crashes occurred.
I-495 Southbound to I-95 Northbound
This loop ramp experienced three crashes in the study period: a rear-end crash, the previously discussed
crossover crash, and a truck rollover crash. The rear-end crash occurred at the entry to the ramp when a
truck rear-ended a car. Driver inattention was cited as a cause. The rollover crash occurred near the end of
the compound curve. No rollover warning signs are posted on the ramp.
I-95 Southbound to I-495 Northbound
This ramp experienced two crashes in the study period: a rollover crash that did not involve a truck and a
merge related crash at the end of the ramp. The rollover crash involved a school van that lost control in
wet conditions, struck the curb, left the road and rolled over. The merge related crash also occurred in wet
conditions and involved a vehicle skidding across the ramp into the travel lane, where it struck a truck. A
W1-13 Truck Rollover sign with 25 MPH supplemental plaque is located on the left side at the entrance
to the ramp, and a second rollover sign is located at the beginning of the curve to the right at the end of
the ramp. W1-8 Chevron arrows are included for the curve to the left in the middle of the ramp and the
curve to the right at the end of the ramp.
I-495 Northbound to I-95 Southbound
This loop ramp experienced two truck rollover crashes and one single vehicle truck crash in the study
period. Two rollover crashes occurred in the loop near the end of the compound curve. Speed was cited as
a direct factor in one crash, and may have been a factor in the second crash which involved a truck
striking the curb and then losing control and rolling over. The single vehicle truck crash occurred at the
end of the ramp where a truck struck the guardrail at the end of the ramp protecting the bridge abutment.
No rollover warning signs are posted on the ramp.
I-495 Northbound to I-95 Northbound
This ramp experienced one rear-end crash and two crossover crashes in the study period. The rear-end
crash occurred at the entry to the ramp and involving a car stopping short and being struck by a truck. The
crossover crashes involved a car on the loop ramp from I-95 Northbound to I-495 Northbound which left
the ramp, crossed over to the I-495 Northbound to I-95 Northbound ramp and hit a truck. One of the
crashes involved contact with a tractor trailer, while the other involved a light truck. No truck rollover
crashes occurred on this ramp.
Page 4
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
I-95 Northbound to I-495 Northbound
This loop ramp experienced three crashes in the study period: the two previously discussed crossover
crashes and a merge related crash. The merge related crash occurred at the end of the ramp and was a
chain reaction crash in which a truck almost hit a car, which then swerved, causing another truck to
swerve to the left and strike another car. A rollover warning sign with a 25 MPH advisory plaque is
located on the left side at the entrance to the ramp.
I-495 Southbound to I-95 Southbound
This ramp experienced two rollover crashes in the study period. One rollover crash occurred at the entry
to the ramp when the driver was late in entering the turn and overturned the vehicle. The second crash
occurred near the end of the ramp; speed was cited as a factor. No rollover warning signs are posted on
the ramp.
I-95 Southbound to I-495 Southbound
This loop ramp experienced one rollover crash and one rear-end crash in the study period. The rollover
crash involved a vehicle that stopped short, causing a truck operator to brake hard and lose control of the
vehicle, which then overturned. The truck driver was cited for speeding. The rear-end crash occurred at
the end of the ramp when a truck was rear-ended by a car during construction when the breakdown lane
was in use as a travel lane. No rollover warning signs are posted on the ramp.
Automatic Traffic Recorder (ATR) data collected in February of 2012 were made available to audit
participants. The data is summarized in Table 2 and included in the Appendix.
Table 2. Ramp Traffic Data
Ramp
2012 ADT
Tph
Tad
I-95 NB to I-495 SB
10,800
6%
8%
I-495 SB to I-95 NB
10,200
4%
5%
I-95 SB to I-495 NB
19,500
4%
9%
I-495 NB to I-95 SB
12,200
2%
6%
I-495 NB to I-95 NB
7,100
2%
5%
I-95 NB to I-495 NB
11,300
1%
5%
I-495 SB to I-95 SB
11,400
3%
6%
I-95 SB to I-495 SB
7,000
1%
4%
ADT: Average Daily Traffic
Tph: Truck Percentage, Peak Hour of Traffic
Tad: Truck Percentage, All Day Traffic
.
Page 5
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Audit Observations
Following a brief introduction to the RSA process, the audit participants were asked to discuss safety
issues and other factors that lead to the occurrence of truck crashes including rollover crashes at the I95/I-495 interchange. Audit participants were presented with crash information, viewed a video recording
of each ramp, and noted safety issues and contributing factors both during and following the video.
A summary of the issues common to all ramps is included, followed by a summary of issues that relate to
a specific ramp only.

Exit/Ramp Signage – It was noted that current MassDOT standard practice when signing ramps is to
provide both W13-2 “EXIT XX MPH” and W13-3 “RAMP XX MPH” advisory speed signs. Existing
ramp speed signage is inconsistent; only three out of the eight ramps have both exit and ramp speed
signage, and the I-95 Southbound to I-495 Northbound ramp displays different speeds for each.

Ramp Delineation - In-pavement reflectors are not
provided along any of the study ramps. Reflectors
would help delineate the ramp for nighttime travel.
Delineator posts are also not provided along the
study ramps. It was noted that delineator posts may
help prevent crossover crashes by providing
additional guidance at night and increasing driver
awareness of the ramp edge and the curbed area
between the loop ramp and the outside ramp.

Lack of Delineation
Rollover Signage – Existing rollover signage is
I-95
NB to I-495 NB
inconsistent and is typically not repeated at the final
curve near the end of the ramp, where the majority of rollover crashes occur.

Inadequate Acceleration Lane Length – It was suggested that the history of merge crashes and/or rearend crashes at the end of the ramps is a result of inadequate room for driver acceleration, and that
drivers feel the need to quickly accelerate to merge into the travel lane. This is especially true of the I95 Southbound to I-495 Northbound ramp, where a rollover crash and a merge related crash at the
end of the ramp were attributed to speed under wet road conditions. It was noted that the existing
bridge structure carrying I-495 over I-95 limits the ability to extend acceleration lane length between
the loop ramps on both highways.

Weaving - I-95 and I-495 both provide a weaving lane between the entering loop ramp and the exiting
loop ramp. This lane is not delineated in either direction on either highway, resulting in no defined
separation between the weaving lane and the inside travel lane.
I-95 Northbound to I-495 Southbound

Rollover Signage – A rollover sign is located at the entry to the ramp, with no additional rollover
signs or chevron arrows. One rollover crash occurred near the end of the ramp.
Page 6
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
I-495 Southbound to I-95 Northbound

Rollover Signage – No rollover or chevron signage is provided on this ramp, where one rollover crash
and one crossover crash occurred.

Diesel Fuel – It was noted that the ramp may become slick from excess diesel fuel that spills on the
ramp from trucks that recently refueled in Plainville.
I-95 Southbound to I-495 Northbound

Ramp Speed Signage – This ramp has an Exit advisory speed sign with a 30 MPH limit and a Ramp
advisory speed sign with a 25 MPH limit. These signs are too closely spaced, which presents
confusion and may cause drivers to enter the ramp at an unsafe speed.

Rollover Signage – Although this ramp provides two
rollover signs, no supplemental speed plaque is
provided on the rollover sign located at the entrance
to the final curve, where the rollover crash involving
a school van occurred. Chevron arrows are provided
for the middle curve to the left and the final curve to
the right, although it appears that some are missing
from the final curve.

Rollover and Chevron Signage
Pavement Condition – Worn pavement can have a
lower friction coefficient which can be related to an increased risk of rollover crashes, especially
under wet conditions. The rollover crash and a merge related crash both occurred under wet
conditions. It is unknown when the ramp and the merge area with I-495 were last resurfaced.

Merge Signage – It was noted that deficiencies may exist in merge signage due to
the two crashes involving vehicle speed near the end of the ramp. Existing merge
signage consists of a typical W4-1R Merge sign on the I-495 mainline in advance
on the ramp merge. Previously stated deficiencies in acceleration lane length are
also a potential contributing factor in merge-related crashes.
I-495 Northbound to I-95 Southbound

Rollover Signage – No rollover signage is provided on this ramp, where one rollover crash and one
crossover crash occurred. Four chevron signs are located in the middle of the ramp loop, but are
lacking from the beginning and end of the ramp where the curvature is greatest. The lack of chevron
signs was specifically noted as a safety concern.

Weaving – The existing geometry of the interchange provides a short weaving area between exiting
traffic and traffic entering the ramp from I-95 Southbound to I-495 Southbound. It is in this area that
a truck hit the guardrail, although it should be noted that inattention was cited as a factor in that crash.
Page 7
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
I-495 Northbound to I-95 Northbound

Rollover Signage – No rollover signage is provided on this ramp, although no rollover crashes
occurred on this ramp. Two crossover crashes left the adjacent loop ramp and struck vehicles on this
ramp.
I-95 Northbound to I-495 Northbound

Rollover Signage – A rollover sign is located at the entry to the ramp, with no additional rollover
signs or chevron arrows. Two crossover crashes occurred on the ramp.

Guide Sign – The last in a series of advance guide signs for an interchange is the Exit Direction sign,
confirming the destination, location and direction of the exit. This sign is typically located at the
beginning of a deceleration lane or at the beginning of the ramp gore. Due to the overhead bridge
structure carrying I-495 over I-95, two Exit Direction signs
are located at this ramp – one on the bridge structure, and
one ground mounted to the right of the ramp entry
following the bridge structure. It was noted that this ground
mounted sign is not clearly visible and in fact blocks
visibility of the ramp speed advisory sign and the rollover
warning sign.

Stormwater Flow – It was noted that water flows across the ramp during rain events, which reduces
pavement friction and can cause vehicles to hydroplane.
I-495 Southbound to I-95 Southbound

Ramp Speed Signage – This ramp has a Ramp advisory speed sign with a 30 MPH limit. It was
suggested that this advisory speed limit is too high for the ramp geometry.

Rollover Signage – No rollover signage is provided on this ramp, where one rollover crash occurred.

Traffic Congestion – It was noted that traffic slows down and sometimes backs up on I-95
Southbound south of I-495, which can impact operations of the ramp. No crashes related to merging
involving trucks were identified for this ramp.
Page 8
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
I-95 Southbound to I-495 Southbound

Guide Sign – The ground mounted Exit Direction sign for
this exit is missing. It was noted that the ground mounted
exit direction signs for the loop ramps to I-495 from I-95
were relocated to the exit gore during a bridge construction
project, and then were to be relocated back to their original
ground mounted location on the right side following
construction. It was theorized that the sign at this location
was not relocated following construction.

Mile Marker Sign – The existing ramp speed advisory sign is partially blocked by a mile marker sign,
as can be seen in the above picture.

Rollover Signage – No rollover signage is provided on this ramp. A rollover crash occurred at the
entry to the ramp, but may have been due to another motorist and not related to the ramp geometry.
Page 9
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Potential Safety Enhancements
Audit participants identified safety issues and recommended potential improvements to address these
issues. These improvements are intended to reduce the number of rollover crashes, reduce the severity of
all crashes and increase the overall safety of the I-95/I-495 interchange. Specific recommendations are
discussed in detail in this section and summarized in Table 3. Each improvement considered has been
categorized as short-term, mid-term, or long-term based on the definitions shown in Table 2.
Additionally, a cost category has been assigned to each improvement based on the parameters set forth in
Table 2.
Table 3. Estimated Time Frame and Costs Breakdown
Time Frame
Short-term
<1 year
Costs
Low
Mid-term
1–3 years
Medium
Long-term
>3 years
High
<$10,000
$10,000–$50,000
>$50,000

Update Exit and Ramp advisory speed signage to be consistent with current
MassDOT practice. New “EXIT 25 MPH” signs should be placed at or
immediately prior to the overhead exit direction sign, while the “RAMP 25
MPH” sign should be placed on the right side of the ramp at the end of the
paved gore. Combined “ramp alignment/advisory speed” signs as shown at right
should be used for the loop ramps. This is a short-term, low cost improvement.
Proposed W13-2 “EXIT 25 MPH” and W13-3 “RAMP 25 MPH” signs should
be 60”x48”, while the combined ramp alignment/advisory speed signs (W13-6
and W13-7) should be 72”x48”. All signs should use fluorescent high intensity
yellow aluminum sheeting. All new signs should display 25 MPH, which
addresses the existing discrepancy at the I-95 Southbound to I-495 Northbound ramp, and reduces the
ramp advisory speed for the I-495 Southbound to I-95 Southbound ramp. All existing ramp advisory
speed signs should be removed.

Update truck rollover signs for ramps where rollover or crossover crashes have occurred. This is true
of the following ramps:
o
o
o
o
o
o
I-95 Northbound to I-495 Southbound
I-495 Southbound to I-95 Northbound (loop)
I-95 Southbound to I-495 Northbound
I-495 Northbound to I-95 Southbound (loop)
I-95 Northbound to I-495 Northbound (loop)
I-495 Southbound to I-95 Southbound
All ramps identified above should have new 48”x48” W13-1 Truck Rollover signs with a 25 MPH
supplemental plaque. The outside (non-loop) ramps should have an additional rollover sign with
supplemental plaque at the beginning of the final curve to the right at the end of the ramp, where the
threat of rollover is greatest. This is a short-term, low cost improvement. All signs should use
Page 10
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
fluorescent high intensity yellow aluminum sheeting. All existing truck rollover signs should be
removed.

Provide new 42”x48” W1-8 Chevron signs for all ramps where truck rollover
signage is to be updated. Chevron arrows should be placed along all curves on the
ramp, and all existing chevron signage should be removed. Signs should have a
fluorescent high intensity yellow background. Exact quantities and locations of
chevron signs should be determined by MassDOT. This is a short-term, low cost
improvement.

Replace H1-2 warning cluster panels in the exit ramp gores with larger 36”x36” signs, which is the
current MassDOT standard for Interstate highway exit gores. Existing H1-2 panels are 24”x24”. This
is a short-term, low cost improvement.

Provide yellow delineator posts along the curbed area between the outside ramps and loop ramps on
all four quadrants of the interchange. This improvement will increase visibility at night, which may
reduce the likelihood of crossover crashes. This is a short-term, low cost improvement. Delineator
posts should be installed in sleeves, which will facilitate maintenance if they are knocked down.

Investigate pavement condition for all ramps. It is unknown when ramps were last resurfaced. If
resurfacing is necessary, high friction pavement should be considered. It was noted during a previous
truck rollover RSA at the I-95/I-295 intersection in Attleboro that the state of Kansas has reported
success with high friction pavements in high rollover crash locations. This type of pavement should
be researched to determine its feasibility at the I-95/I-495 interchange. Increased pavement friction
could help keep the truck’s tires on the pavement and in turn prevent tipping and rollovers. This is a
mid-term, high cost improvement that requires additional study.

Install in-pavement reflectors along all ramps at the interchange. MassDOT has installed recessed, inpavement reflectors, also known as pavement markers, along many miles of highway throughout the
Commonwealth. These reflectors should be installed along all ramps at the I-95/I-495 interchange to
increase visibility and awareness of the ramp geometry at night. This is a short-term, medium cost
improvement. An evaluation of pavement condition described above should precede installation of
pavement markers. If ramps require resurfacing, pavement markers can be installed at the same time
as the resurfacing. If the pavement condition is generally good, but the pavement is deemed to be too
old for the installation of recessed markers, consideration should be given to installing raised markers
located just outside of the edge line.

Investigate the feasibility of providing acceleration lanes at the end of all four outer ramps. Under
current conditions, drivers are known to accelerate while still navigating the ramp in order to reach
their desired speed for merging into free flow traffic along the mainline. Providing adequate
acceleration lanes would allow the driver to remain at an appropriate speed for the ramp and then use
the acceleration lane to accelerate to merging speed. This is a long-term, high cost improvement.

Provide new pavement markings for weaving lanes consistent with Figure 3B-10 of the Manual on
Uniform Traffic Control Devices. This will provide delineation of the weaving lane where none exists
Page 11
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
today. This is a short-term, low cost improvement that should be applied to the weaving lane between
the two loop ramps in both directions on both I-95 and I-495.

Investigate merge crashes involving all vehicles on the I-95 Southbound to I-495 Northbound ramp.
Two crashes occurred on this ramp that involved vehicle speed on a wet roadway surface at the top of
the ramp. If the ramp merge shows a significant history of merge-related crashes involving all
vehicles, additional signage or geometric modifications should be considered. If the crash history
includes a high percentage of crashes in wet weather conditions, drainage improvements may be
necessary. This is a short-term, low cost improvement that may trigger other long-term
improvements.

Remove the ground mounted guide sign for the I-95 Northbound to I-495 Northbound ramp and
replace it with a new sign in the exit gore, and provide a guide sign in the exit gore for the I-95
Southbound to I-495 Southbound ramp. It was noted that the existing sign on the I-95 Northbound to
I-495 Northbound ramp blocks visibility of other existing signage and is not clearly visible due to the
proximity of the bridge structure. The missing sign on the I-95 Southbound to I-495 Southbound
ramp should be replaced and mounted in the exit gore. Installing new signs at both locations will
insure a consistent appearance in signage. These signs will replace the existing exit gore signs, which
should be removed. The existing memorial at the base of the existing sign on the I-95 Northbound to
I-495 Northbound ramp should be relocated to the base of the new sign in the exit gore. It was noted
that while placing guide signs in the exit gore is atypical and not consistent with other exit gore
signage along I-95, it is acceptable for an Interstate to Interstate connection. This is a short-term,
medium cost improvement.

Relocate the mile marker sign for the I-95 Northbound to I-495 Northbound ramp. The location of the
relocated sign should be considered relative to other signage recommendations. This is a short-term,
low cost improvement.

Investigate stormwater flow along the I-95 Northbound to I-495 Northbound ramp. Existing catch
basins are provided on the right side of this ramp, but it was suggested that water sheet flow extends
beyond these basins across the ramp. It should be determined if existing drainage is adequate for the
ramp geometry. This is a short-term, low cost improvement.

Study the crash history of the I-495 Southbound to I-95 Southbound ramp due to concerns over traffic
congestion. If the ramp shows a significant history of rear-end crashes involving all vehicles, signage
or geometric modifications should be considered. This
is a short-term, low cost improvement.

Consider “rollover hazard” advisory signs on both I-95
and I-495 prior to the I-95/I-495 interchange. These
panels would be similar to signs currently in place on
I-93 prior to the I-95/Rt. 128 interchange in Woburn,
pictured at right. Rollover advisory signs would be a
short-term, medium cost improvement.
Page 12
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Summary of Road Safety Audit
Table 3 summarizes potential recommendations discussed by the audit team. The recommendations are
categorized based on the potential safety payoff, as well as by time frame and cost. The safety payoff is a
qualitative judgment of the effectiveness of the potential safety improvements. The cost is a preliminary
order of magnitude estimate based on prior experience with roadway and safety improvements. Cost does
not include inflation or construction administration.
Page 13
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Table 4. Potential Safety Enhancement Summary
Safety Issue
Safety Enhancement
Exit/Ramp
Signage
Update Exit and Ramp advisory speed signage to be consistent
with current MassDOT practice.
Safety Payoff Responsibility Time Frame
Cost
Medium
MassDOT
Short-term
$6,500
Rollover
Signage
Update truck rollover signs for ramps where rollover or crossover
crashes have occurred.
High
MassDOT
Short-term
$3,000
Rollover
Signage
Provide new 42”x48” W1-8 Chevron signs for all ramps where
truck rollover signage is to be updated.
High
MassDOT
Short-term
$10,000
Ramp
Delineation
Provide yellow delineator posts along the curbed area between
the outside ramps and loop ramps on all four quadrants of the
interchange. Posts should be installed in sleeves to facilitate
maintenance.
High
MassDOT
Short-term
$5,000
Pavement
Condition
Investigate pavement condition for all ramps. Determine when
last resurfacing took place, and consider high friction pavement if
resurfacing is necessary.
High
MassDOT
Mid-term
TBD
Ramp
Delineation
Install in-pavement reflectors (pavement markers) along all ramps
at the interchange. An evaluation of pavement condition should
precede installation of pavement markers.
High
MassDOT
Short-term
$25,000
Inadequate
Acceleration
Lane Length
Investigate the feasibility of providing acceleration lanes at the
end of all four outer loop ramps.
High
MassDOT
Long-term
TBD
Weaving
Provide new pavement markings for weaving lanes consistent
with Figure 3B-10 of the Manual on Uniform Traffic Control
Devices
Medium
MassDOT
Short-term
$5,000
Merge Signage
Investigate merge crashes involving all vehicles on the I-95 SB to
I-495 NB ramp, and consider signage updates or geometric
modifications if warranted.
High
MassDOT
Short-term
(Study)
TBD
Guide Sign
Remove the existing ground mounted guide sign for the I-95 NB
to I-495 NB ramp and replace it with a new sign in the exit gore
(include relocated memorial). Provide a new ground mounted
guide sign for the I-95 SB to I-495 SB ramp in the exit gore.
Medium
MassDOT
Short-term
$6,000
Mile Marker
Signage
Relocate the mile marker sign at the I-95 NB to I-495 NB ramp.
The location of the relocated sign should be considered relative
to other signage recommendations.
Medium
MassDOT
Short-term
$500
Page 14
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Table 4. Potential Safety Enhancement Summary
Safety Issue
Safety Enhancement
Safety Payoff Responsibility Time Frame
Cost
Stormwater Flow Investigate stormwater flow along the I-95 NB to I-495 NB ramp.
Medium
MassDOT
Short-term
TBD
Traffic
Congestion
Study the crash history of the I-495 SB to I-95 SB ramp due to
concerns over traffic congestion.
Medium
MassDOT
Short-term
TBD
Rollover
Signage
Consider “rollover hazard” advisory signs on both I-95 and I-495
similar to those installed on I-93 in Woburn.
Medium
MassDOT
Short-term
$15,000
Page 15
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Appendix A. RSA Meeting Agenda
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Appendix B. RSA Audit Team Contact List
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Appendix C. Crash Diagram
Legend
N
Crash Type
e
Crossover
0
Merge Related
e
Rear End
0
Single Vehicle/Rol love r
Q
Municipal Boundary
--80==--==
~eel
~7!!!.4lJPQI
Road Safety Audit –Truck Rollover Crashes—I-95/I-495 Interchange—Foxborough/Mansfield, MA
Prepared by BETA Group, Inc.
Appendix D. Traffic Volume Data
1. Off-Ramp from I-95 SB to I-495 NB
2012 actual ADT = 19,500
2032 forecast ADT = 21,500
Tph = 4%
Tad = 9%
2. Off-Ramp from I-495 NB to I-95 SB
2012 actual ADT = 12,200
2032 forecast ADT = 15,600
Tph = 2%
Tad = 6%
3. Off-Ramp from I-95 SB to I-495 SB
2012 actual ADT = 7,000
2032 forecast ADT = 7,600
Tph = 1%
Tad = 4%
4. Off-Ramp from I-495 SB to I-95 SB
2012 actual ADT = 11,400
2032 forecast ADT = 16,400
Tph = 3%
Tad = 6%
5. Off-Ramp from I-95 NB to I-495 SB
2012 actual ADT = 10,800
2032 forecast ADT = 15,100
Tph = 6%
Tad = 8%
6. Off-Ramp from I-495 SB to I-95 NB
2012 actual ADT = 10,200
2032 forecast ADT = 11,700
Tph = 4%
Tad = 5%
7. Off-Ramp from I-95 NB to I-495 NB
2012 actual ADT = 11,300
2032 forecast ADT = 14,200
Tph = 1%
Tad = 5%
8. Off-Ramp from I-495 NB to I-95 NB
2012 actual ADT = 7,100
2032 forecast ADT = 8,300
Tph = 2%
Tad = 5%