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Bechtel et al. TRB #15-1947
1
CHARACTERIZING BRIDGE FUNCTIONAL OBSOLESCENCE USING 1
CONGESTION PERFORMANCE MEASURES DETERMINED FROM 2
ANONYMOUS PROBE VEHICLE DATA 3
by 4
Andrew J. Bechtel* 5 The College Of New Jersey 6
2000 Pennington Road 7 Ewing, NJ 08628 8 (609) – 771 -2475 9 [email protected] 10
Thomas M. Brennan Jr. 11 The College of New Jersey 12
Jhenifer Mesquita de Araujo 14 The College of New Jersey 15
*Corresponding author. Email: [email protected] 17
Word Count: 4,363 words + 11 * 250 words/(figure-table) = 7113 words 18
November 4, 2014 19 20
Bechtel et al. TRB #15-1947
2
ABSTRACT 1
In the last few years, anonymous probe vehicle data has become a reliable means to 2
evaluate travel time reliability, as well as congestion conditions along highways and major 3
arterials. The data is collected using telematics from commercial and private cellular phones, 4
GPS devices, and on-board vehicle computers. The probe vehicle data is commercially available 5
in one-minute increments along spatially defined roadway segments of varying lengths. This data 6
is being incorporated into local and statewide reports to measure congestion conditions of 7
highway and arterial systems. This paper uses crowd sourced anonymous probe vehicle data to 8
evaluate congestion duration at functionally obsolete bridge structures. The bridges selected were 9
functionally obsolete due to poor ratings in their deck geometry. as defined by National Bridge 10
Inventory (NBI) rating system. These deficiencies are based on a bridge’s traffic capacity as a 11
function of its geometry and the Average Daily Traffic (ADT). These conditions are directly 12
expected to impact the speed and volume of traffic crossing over the bridge causing congestion. 13
An evaluation of the travel times at bridge locations was conducted to determine if a measurable 14
amount of congestion could be observed using probe vehicle data. 15
The methodologies presented in this paper were applied to 37 bridge structures in 16
Burlington County, New Jersey. Approximately 35 million speed data records were analyzed for 17
the 37 bridges to measure congestion. The congestion performance measures were compared to 18
the NBI rating to determine if congestion existed at the bridges as predicted by the NBI system. 19
The comparison showed that a poor rating in deck geometry from the NBI system was not a 20
strong indicator of congestion. The congestion evaluation methodologies presented in this paper 21
where then combined with existing NBI structural ratings to demonstrate alternative bridge 22
management strategies. 23
Bechtel et al. TRB #15-1947
3
INTRODUCTION 1
The American Society of Civil Engineers (ASCE) 2013 Report Card for America’s Infrastructure 2
gave the country’s bridges an overall grade of C+. The Federal Highway Administration (FHWA) 3
estimates that $20.5 billion dollars needs to be invested annually to correct all of the deficient bridges in 4
the US by the year 2028. This is an annual increase of $8 billion dollars. The ASCE cites one way to 5
mitigate these deficient bridges is to improve asset management methodologies. Currently, 24.9% 6
(151,238) of the country’s bridges are characterized as deficient (1). These deficient bridges are 7
characterized as structurally deficient or functionally obsolete, but can be both in some cases. A 8
structurally deficient bridge requires significant maintenance, rehabilitation, or replacement. These 9
bridges must be inspected at least every year since critical load-carrying elements were found to be in 10
poor condition due to deterioration or damage. (1). Conversely, a functionally obsolete bridge no longer 11
meets the current standards that are used today. Examples are narrow lanes or low load-carrying capacity. 12
(1). 13
In the United State, Bridge deficiency is determined using the Recording and Coding Guide for 14
the Structure Inventory and Appraisal of the Nations Bridges (2). The National Bridge Inventory (NBI) 15
keeps a record of the scores that have been produced by local and state agencies. A bridge is considered 16
structurally deficient (SD) if any of the conditions in Table 1 are met. 17
Table 1. Structurally deficient NBI scoring categories (4). 18
Categories NBI Item Number Deficiency Score Deck Condition 58 4 Superstructure 59 4 Substructure 60 4 Structural Evaluation 67 2 Waterway Adequacy 71 2
Likewise, a bridge is categorized as Functionally Obsolete (FO) if any of the conditions in Table 19
2 are met. 20
Bechtel et al. TRB #15-1947
4
Table 2. Functionally obsolete NBI scoring categories (4). 1
Categories Description NBI Item Number Deficiency Score Structural Evaluation (S) Capacity evaluation 67 3 Waterway Adequacy (W) Flood evaluation 71 3 Deck Geometry (D) Bridge width vs. ADT and # of lanes 68 3 Under Clearances (U) Height over roadway beneath 69 3 Approach Roadway Alignment (A) Angle between bridge and approach 72 3
Based on NBI standards, any bridge found to be structurally deficient supersedes a functionally 2
obsolete classification. A bridge found to be functionally obsolete may be due to low scores in 3
the structural evaluation (S) or under clearances (U), which obstruct large heavy vehicles, 4
requiring them to choose an alternate route. This obstruction will only minimally interfere in the 5
daily flow of traffic for the average passenger vehicle. Bridges classified as functionally obsolete 6
due to deck geometry (D), approach roadway alignment (A), or waterway adequacy (W) have 7
geometries or obstructions which cause a reduction in speed. Roadway geometry that differs 8
from base condition has been shown to cause a reduction in free flow speed (3). In the presence 9
of other vehicles, this slowdown can reduce the level of service for the bridge. This reduction in 10
service is considered congestion. A bridge determined to have poor deck geometry (D) does not 11
have adequate width as compared to Average Daily Traffic (ADT) and lane number 12
requirements. Poor deck geometry can also be a function of insufficient vertical clearance. A 13
bridge with poor roadway alignment (A) is expected to require a speed reduction upon approach 14
to improve throughput. A bridge with poor waterway adequacy (W) frequently floods, making it 15
impassable during certain periods. All of these conditions, except lack of vertical clearance, are 16
expected to result in a reduction in speed which can lead to congestion. An analysis of the 1992 17
NBI showed the individual leading cause for deficiency (including both structurally deficient and 18
functionally obsolete bridges) was deck geometry (4). 19
Bechtel et al. TRB #15-1947
5
While the rating factors for deck geometry, road alignment, and to some extent 1
waterway adequacy, are meant to represent areas where congestion might occur, they are in 2
themselves not measures of congestion. The NBI uses ADT and bridge and roadway geometries 3
to model conditions where congestion is likely. In the past it has not been economically feasible 4
to directly measure and quantify congestion. With the recent development of regionally 5
dispersed commercially available anonymous probe vehicle speed data, it is becoming possible 6
to spatially and temporally evaluate congestion occurrence (5). Recent studies have applied 7
performance measures based on this data to evaluate highway corridors, crash incidents, and 8
construction projects (6, 7, 8, and 9). 9
This paper presents an evaluation of congestion for bridges categorized as functionally 10
obsolete due to deck geometry in Burlington County, New Jersey. The evaluation consists of 11
congestion metrics calculated from crowd sourced anonymous probe vehicle data. The 12
congestion metrics presented are used to determine the presence, time, and the intensity of 13
congestion at, or before, a functionally obsolete bridge. These congestion values are then 14
compared to the NBI rankings to determine if the current bridge ranking parameters effectively 15
convey congestion, and therefore functional obsolescence. 16
BURLINGTON COUNTY NBI DATA 17
Burlington County, New Jersey reported 331 bridges in the 2013 NBI (Figure 1). Of the 18
331 bridges, 14 can be classified as structurally deficient and 112 can be classified as 19
functionally obsolete. Approximately 38% of the bridge structures in Burlington County are 20
deficient in some way, which is 13% higher than the national average. The largest cause for 21
functional obsolescence is deck geometry (69 bridges) followed by insufficient under clearances 22
(39 bridges). 23
1
2
3
4
5
6
7
8
9
10
11
12
13
Bechtel et
(deck geo
the flow
bridges m
Traffic M
vehicle d
Many of
the highw
deficient
T
indicated
deficienc
t al.
The bridges
ometry). The
of traffic by
meet this req
Message Cha
data. Of the 7
the bridges
way bridge p
in some wa
Fig
Table 3 illustr
d by SD whil
cy is given ei
considered
ese bridges w
y limiting the
quirement for
annel (TMC)
70 bridges, o
identified in
population is
y (4).
gure 1. NBI
rates the NB
le Functiona
ither by a D
in this study
were chosen
e speed and t
r the study.
) in order to
only 37 (Figu
n this study a
s located on n
bridges with
BI rated defic
al Obsolescen
for Deck Ge
6
y are rated fu
n because the
traffic capac
However, a
evaluate the
ure 2), are sp
are located o
non-state ma
hin Burlingto
ciency of eac
nce is indica
eometry, a U
unctionally o
eir deficienci
city of the br
bridge must
e congestion
patially loca
on county roa
aintained roa
on County, N
ch bridge. St
ated by FO. T
U for Under
obsolete due
ies are expec
ridge. Of the
t be located
conditions u
ated near TM
ads. Nationa
ads, and half
New Jersey.
tructural De
The reason f
Clearances,
TRB #15
to their wid
cted to impe
e 331 bridge
adjacent to a
using probe
MCs (Table 3
ally about ha
f of those are
ficiency is
for the
or a DU for
-1947
dth
ede
es, 70
a
3).
alf of
e
r
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Bechtel et
both. All
and none
these brid
serviceab
deck con
68), unde
(NBI Item
STRANE
factor att
permitted
the requi
high func
yearly co
Fig
t al.
l of the bridg
e of the deck
dges should
bility and fun
ndition (NBI
er clearance
m 72), ADT
ET Highway
tempts to det
d loads. It us
red traffic vo
ctioning brid
ongestion ho
gure 2. Funct
ges given in
k geometry p
theoretically
nctional obso
Item 58), str
(NBI Item 6
(NBI Item 2
y Designation
termine if a b
ses the bridg
olume. The
dge. Table 3
urs for each
tionally obso
Table 3 are
roblems are
y experience
olescence us
ructural eval
69), waterwa
29), number
n (NBI Item
bridge has a
ge width and
factor is take
3 also includ
bridge; thes
olete bridges
7
functionally
related to in
e congestion
sed in the NB
luation (NBI
ay adequacy
of lanes (NB
m 100), and v
adequate cap
ADT to det
en out of a m
es the conge
se values are
to be studied
y obsolete du
nsufficient v
. Table 3 giv
BI. This ratin
I Item 67), d
(NBI Item 7
BI Item 28),
vertical clear
pacity and cle
termine if the
maximum of
estion speed
e explained i
d in Burlingt
ue to their de
vertical cleara
ves the rating
ng is evalua
deck geomet
71), approac
, road width
rance (NBI It
earances for
e bridge can
f 30, with 30
threshold an
in the follow
ton County, N
TRB #15
eck geometry
ance. All of
g for
ated using the
try (NBI Item
ch road align
(NBI Item 5
tem 53). The
r legally
n accommoda
0 representin
nd the total
wing section.
New Jersey.
-1947
y,
e
m
nment
51),
e
ate
ng a
Bechtel et al. TRB #15-1947
8
Table 3. Functionally obsolete bridges in Burlington County, New Jersey. 1
Structure Number Deficiency
Serviceability and Functional Obsolescence
Congestion Speed
Threshold (MPH)
Congestion Hours
314154 FO-D 26 36 56.75
314155 FO-D 25 36 224.75
327153 FO-DU 22 47 34.50
327173 FO-D 25 31 48.00
327174 FO-D 24 47 26.25
328157 FO-D 24 31 7.75
328169 FO-D 26 48 120.00
3000004 FO-DU 22 25 25.25
3000007 FO-D 26 25 0.00
03C3105 FO-D 25 15 0.75
03C3220 FO-D 25 29 23.25
03C3600 FO-D 26 27 2.50
03C4004 SD/ FO-D 19 28 1.00
03C4130 SD/ FO-D 24 26 1.25
03C5780 FO-D 24 27 17.5
03D0360 FO-D 25 28 0.75
03D3015 FO-D 25 32 0.50
03D3063 FO-D 20 23 3.00
03D3068 FO-D 26 27 0.00
03D4100 FO-D 26 14 11.50
03D4260 FO-D 26 20 2.00
03D4270 FO-D 24 25 0.50
03D4560 FO-D 20 33 0.00
03D4570 FO-D 26 33 0.00
03D4870 FO-D 25 25 18.75
03D4900 FO-D 25 18 15.50
03D5110 FO-D 25 23 2.75
03D5250 FO-D 25 25 14.50
03E4550 SD/ FO-D 22 21 75.50
03G3900 FO-D 25 27 0.00
03H4100 FO-D 26 33 6.25
03H8001 SD/ FO-D 24 35 0.00
03H8520 FO-D 25 34 0.00
03H8620 FO-D 24 28 4.00
M033940 FO-DU 21 23 11.25
M050950 FO-D 24 46 31.00
M055100 FO-DU 22 28 28.75
Bechtel et al. TRB #15-1947
9
CONGESTION EVALUATION 1
Congestion at the bridge structures is determined using crowd sourced anonymous probe 2
vehicle data. This data comes in the form of time stamped speed data for each TMC. For this 3
study, the entire year of 2013, consisting of approximately 35 million speed records, was 4
analyzed for each bridge in both directions. The data is sorted into 15-minute bins for each day 5
of the year. Congestion is tied to a reduction in speed. In this study significant congestion was 6
assumed to occur when speeds dropped below a defined threshold. Previous studies had used 7
45mph as the congestion threshold (6). For this study, the congestion threshold speed was based 8
on the 70th percentile space mean speed (SMS) for each TMC, and it was calculated using speed 9
data between the hours of 0200 and 0600 each day (Table 3). Congestion hours are determined 10
using a binary indicator, where each SMS is compared to the congestion threshold speed 11
calculated for each TMC. If the SMS falls below the threshold, the 15-minute bin it is assigned a 12
value of 1; if it is above the speed value it is assigned a value of 0. The resulting values can then 13
be summed and divided by 4 to calculate the congestion hours. The congestion hours can be 14
aggregated by hour, day, month, or year. Table 3 gives the yearly congestion hours for the 15
functionally obsolete bridge structures. The monthly data is represented graphically in the 16
stacked bar graph in Figure 3. The top 10 NBI bridges are compared to the calculated congestion 17
hours shown in Table 4. 18
The bridge structures in Figure 3 are organized in order of ascending congestion hours. 19
Seven of the bridges studied experienced no congestion, despite being functionally obsolete due 20
to their deck geometry. This shows that a rating of functionally obsolete due to deck geometry is 21
not an absolute indicator of congestion. The bridge with the worst congestion is bridge 314155. 22
This structure experienced 224.75 congestion hours for the year of 2013, and these congestion 23
Bechtel et al. TRB #15-1947
10
hours are consistent through each month. If there are assumed to be 1500 business related travel 1
hours a year (250 work days and 6 peak hours a day) all but the worst bridges are congested less 2
than 10% of the time. The 10 bridges with the worst NBI serviceability and functional 3
obsolescence ratings are also labeled in Figure 3. Only 5 out of the top 10 worst bridges in 4
Burlington County, as ranked by the NBI, appear in the top 10 most congested bridges. There is 5
a noticeable difference between the rating in the NBI Serviceability and Functional Obsolescence 6
Rating and where congestion is observed. 7
Table 4. Ten bridges with lowest NBI Serviceability and Sufficiency Rating 8
NBI Rank
Structure Number Deficiency
Serviceability and Functional Obsolescence
Congestion Speed
Threshold (MPH)
Congestion Hours
#1 03C4004 SD/ FO-D 19 28 1.00 #2 03D3063 FO-D 20 23 3.00 #2 03D4560 FO-D 20 33 0.00 #4 M033940 FO-DU 21 23 11.25 #5 327153 FO-DU 22 47 34.50 #5 3000004 FO-DU 22 25 25.25 #5 03E4550 SD/ FO-D 22 21 75.50 #5 M055100 FO-DU 22 28 28.75 #9 327174 FO-D 24 47 26.25 #9 328157 FO-D 24 31 7.75
Bechtel et al. TRB #15-1947
11
Figure 3. Monthly congestion hours for 2013. 1
0 50 100 150 200 250
314155
328169
03E4550
314154
327173
327153
M050950
M055100
327174
3000004
03C3220
03D4870
03C5780
0384900
0385250
0384100
M033940
328157
03H4100
03H8620
03D3063
03D4260
03C3600
03D4260
03C4130
03C4004
03C3105
03D0360
03D3015
03D4270
3000007
03D3068
03D4560
03D4570
03G3900
03H8001
03H8520
Congestion Hours
Bri
dge
Num
ber
January
February
March
April
May
June
July
August
September
October
November
December
(NBI Rank #1)
(NBI Rank #2)
(NBI Rank #2)
(NBI Rank #4)
(NBI Rank #5)
(NBI Rank #5)
(NBI Rank #5)
(NBI Rank #5)
(NBI Rank #9)
(NBI Rank #9)
No Congestion Hours
Bechtel et al. TRB #15-1947
12
BRIDGE MANAGEMENT 1
The goal of bridge management is to get the best return on investment. In this case, the 2
return is improved mobility and travel time reliability. This can mean a bridge can be 3
strengthened to carry larger loads and additioinal vehicles, or it can be reconfigured to improve 4
traffic flow. Ultimatly, there are three courses of action that an be taken when evaluating a 5
structure: 6
1. Do nothing 7
2. Repair or retrofit the existing structure 8
3. Replace the structure. 9
To demonstrate how congestion analysis can be used as a tool for the management of 10
bridges, three sample structures will be evaluated. These three structures are Bridge 03C4004 11
(most deficient bridge by NBI Rank, Table 4 ), Bridge 03E4550 (best agreement between 12
congestion analysis and NBI, Table 4), and Bridge 314155 (highest amount of measured 13
congestion Table 3). The structures will be evaluated individually, incorporating their structural 14
condition into the process. 15
Bridge 03C4004 16
Bridge 03C4004 is structurally deficient and functionally obsolete due to its deck 17
geometry. It has a structural evaluation of 2 out of 10, and a serviceability and functional 18
obsolecence rating of 19 out of 30. Bridge 03C4004 carries a city street across the Rancocus 19
Creek; it was constructed in 1909 and improved upon in 2007. Figure 4a shows a close-up aerial 20
view of the bridge. The bridge serves to connect two residential areas. Figure 4b shows a more 21
expansive aerial view of the bridge and its surroundings. Directly southeast of the bridge is I-22
295. Farther to the northwest and southeast, routes 130 and 38 both cross the Rancoucus Creek. 23
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Bechtel et
F
congestio
volumes.
63%. Ba
If the bri
impact. I
be to stre
there is n
there is le
to safety
Bridge 03
B
geometry
a) Clo
t al.
rom the con
on hour per y
. This is in c
ased on its pr
dge has vehi
f the bridge
engthen or re
no need to ex
ess of a need
concerns.
3E4550
Bridge 03E45
y. It has a str
se up view of
4
Figure
ngestion anal
year (Table 3
ontrast to th
roximity to I
icle weight r
were to beco
epair the exis
xpand the bri
d to replace t
550 is structu
ructural eval
f bridge
e 4. Aerial vi
lysis, it has b
3). This bein
he Serviceabi
I-295 there i
restrictions p
ome structur
sting structu
idge to carry
the bridge. T
urally defici
luation of 2 o
13
iew of Bridge
been shown t
ng the case, t
ility and Fun
is no need fo
plassed on it
rally unsafe,
ure. Due to th
y more volum
The only rea
ent and func
out of 10, an
b) Brid
RT 1
03C4
e 03C4004 (1
that Bridge 0
the bridge ad
nctional Obs
or the bridge
, there will n
, the recomm
he low numb
me. If there i
son to replac
ctionally obs
nd a servicea
dge location r
130
4004
10)
03C4004 ha
dequatly han
solecence Ra
to carry hea
not be a larg
mendation fo
ber of conge
is no need fo
ce the bridge
solete due to
ability and fu
related to I-29
RT 38
TRB #15
as a total of o
ndles traffic
ating which i
avy truck tra
e economic
or action wou
estion hours,
or expansion
e would be d
o its deck
unctional
95
I-295
-1947
one
is
affic.
uld
n
due
1
2
3
4
5
6
7
8
9
10
11
12
13
15
Bechtel et
obsolecen
across th
shows a c
of the bri
Fort Dix.
determin
per mont
traffic (1
decreases
speed bet
slowdow
indicator
it is caus
t al.
nce rating of
e Rancocus
close-up aer
idge is locate
. Bridge 03E
ne when thes
th over the en
1). In Figure
s in both the
tween 10 an
wn, the fact th
r that the brid
ing congesti
a) Close
f 22 out of 3
Creek; it wa
rial view of t
ed a signaliz
E4550 experi
e congestion
ntire day wa
e 6, as the co
e AM and PM
d 11 AM. W
hat there is s
dge is influe
ion, it would
Figure
up view of br
30. Bridge 03
as constructe
the bridge, an
zed intersecti
ienced 75.5
n hours occu
as created; th
olor darkens,
M peak hour
While the sign
slowdown an
ncing traffic
d be a good c
18
e 5. Aerial vi
ridge
14
3EA4550 ca
ed in 1932 an
nd Figure 5b
ion, and loca
congestion h
urred, a conto
his diagram i
, the travel s
s. The south
nalized inter
nd congestio
c. Since this
candidate for
iew of Bridge
0
b) B
arries Burling
nd improved
b shows an e
ated off of th
hours in 201
our diagram
is shown in F
speed decrea
hbound lane
rsection may
on in both dir
bridge is bo
r replacemen
e 03E4550 (1
03E4550
Bridge locatio
gton County
d upon in 19
expanded vie
he figure to t
3 (Table 4).
of the avera
Figure 6 for
ases. There a
experiences
y cause some
rections wou
oth structural
nt.
12)
For
Inte
on related to
TRB #15
y Route 616
77. Figure 5
ew. To the s
the northeas
In order to
age traffic sp
both lanes o
are clear
its slowest
e of the
uld be an
lly deficient
rt Dix
rsection
intersection
-1947
5a
outh
st is
peed
of
and
Bechtel et al. TRB #15-1947
15
a) Northbound lane 1
b) Southbound lane 2
Figure 6. Average monthly travel speed per time of day for Bridge 03E4550 3
Bridge 314155 4
Bridge 314155 carries Southbound New Jersy Route 73, a major arterial connecting 5
Philadelphia to I-295 and the New Jersey Turnpike, over New Jersey Route 38 (Figure 7). The 6
Time of Day
Mon
th
Miles per H
our
200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400January
February
March
April
May
June
July
August
September
October
November
December
22
24
26
28
30
32
34AM Peak7-10 AM 4-7 PM
PM Peak
T ime of Day
Mon
th
Miles per H
our
200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400January
February
March
April
May
June
July
August
September
October
November
December
24
25
26
27
28
29
30
31
32
33AM Peak
4-7 PMPM Peak
7-10 AM
1
2
3
4
5
6
7
8
9
11
12
13
14
15
16
17
18
Bechtel et
bridge ha
rating of
out of an
and Func
with Brid
(Figure 7
are clear
hours tha
heading t
A
congestio
causing t
commerc
signal op
over the b
3
t al.
as a structura
25 out of 30
ny bridge stu
ctional Obso
dge 314154,
7a). Figure 8
slowdowns
an the AM h
toward I-295
Although Bri
on could pos
this congesti
cial shopping
peration at th
bridge. Befo
314155
a) Close u
al evaluation
0. In 2013, th
died (Table
lecence ratin
which has a
shows the a
during the A
ours, presum
5 or the Turn
Figur
dge 314155
ssibly be due
ion. There is
g center, as w
hese points c
ore a recomm
up view of bri
n of 6 out of
he bridge exp
3). Despite t
ng of the thr
a similar des
average mon
AM and PM
mably from p
npike.
14
re 7. Aerial v
is structural
e to the bridg
a signalized
well as a sig
ould be caus
mendation fo
idge
16
10, and a se
perienced 22
this finding,
ee bridges e
ign, but only
nthly speed p
peak hours.
people leavin
view of Bridg
lly adequate,
ge deck geom
d intersection
nalized inter
sing traffic s
or the bridge
I-29
Phi
b) B
erviceability
24.75 conge
it has the hi
evaluated. Br
y experience
per time of d
There is gre
ng work in th
ge 314155 (13
, it is experie
metry. How
n just south
rsection on E
slowdown th
e is made, it w
31
95 and NJ Tur
iladelphia
ridge location
and function
estion hours;
ighest (83%)
ridge 314155
ed 56.75 con
day for Bridg
eater slowdo
the greater P
3)
encing cong
wever, other f
on New Jers
East New Jer
hat impacts s
would be pru
14155
rnpike
n related to Ph
TRB #15
nal obsolece
this is the m
) Serviceabil
5 runs parrel
ngestion hour
ge 314155. T
own in the PM
hiladelphia a
gestion. This
factors may
sey RT 73 ne
rsey RT 38.
speed of vehi
udent to per
hiladelphia
-1947
ence
most
lity
llel
rs
There
M
area
be
ear a
The
icles
form
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17
a traffic study of the general area. If they are creating the traffic slow down, the signals can 1
possibly be adjusted to mitigate congestion in the area. Adjusting signal timing is more cost 2
efficient than expanding the bridge. 3
Figure 8. Average monthly travel speed per time of day for Bridge 314155 4
CONCLUSIONS AND FUTURE WORK 5
The evaluation of bridge structural integrity and functional obsolesce is used as a means 6
to determine where capital improvements should be focused. Under the current system, a 7
bridge’s functional obsolesce is partially based on NBI criteria that would indicate a bridge’s 8
inability to effectively provide the necessary capacity for the current traffic volume. The lack of 9
traffic capacity is therefore expected to cause congestion at the bridge structures. This study 10
applied anonymous crowd source probe vehicle data congestion analysis methodologies that are 11
currently used to evaluate roadway performance to a sample set of bridge structures found to be 12
functionally obsolete as defined by NBI. All of the bridges evaluated were functionally obsolete 13
Time of Day
Mon
th
Miles per H
our
200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400January
February
March
April
May
June
July
August
September
October
November
December
34
36
38
40
42
44
46
48
50
52
54AM Peak7-10 AM
PM Peak4-7 PM
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due to their deck geometries with no bridges having vertical clearance issues. The study found 1
that although the NBI rating showed that a bridge should incur congestion; this was not 2
necessarily the case. 3
In total 37, functionally obsolete bridges in Burlington County, New Jersey were 4
evaluated using probe vehicle data for the 2013 calendar year. Of the 37 bridges, 7 experienced 5
no congestion hours at all. Twenty-eight bridges experienced less than 100 hours of congestion 6
for the year, and only two bridges experienced more than 100 congestion hours with the 7
maximum being 224.75 hours. Of the 10 worst ranked structures based on the NBI, only 5 8
appeared in the 10 bridges with the worst measured congestion (Figure 3). The top 2 bridges 9
found to have the highest measured congestion were not ranked in the NBI’s top 10 worst 10
structures (Figure 3/ Table 4). 11
An alternative bridge assessment methodology that combines the measured congestion 12
and travel speed information obtained from probe vehicle data and the NBI structural rating was 13
proposed. This new methodology was then used to make recommendations for three sample 14
bridges. The congestion and speed data proved to provide insight into how the bridge is 15
functioning beyond the NBI Serviceability and Functional Obsolescence rating. It helped provide 16
a clear picture as to which actions to take when determining if repair or replacement were 17
necessary. The next step in vetting this analysis method is to evaluate all of the bridges agency 18
wide, not just the structures determined to be functionally obsolete. This will give a clear picture 19
of how well the NBI ranking picks up bridges which are not adequately handling traffic 20
demands. Also, an economic factor will be tied to congestion hours to evaluate the impact of 21
increased congestion. This factor can then be weighed against the cost of multiple types of 22
corrective measures to evaluate their cost-benefit relationships. 23
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ACKNOWLEDGMENTS 1
The authors would like to thank the Coordenação de Aperfeiçoamento de Pessoal de 2
Nível Superior (CAPES) Foundation - Ministry of Education of Brazil for providing funding for 3
our undergraduate researchers. The contents of this paper reflect the views of the authors, who 4
are responsible for the facts and the accuracy of the data presented herein, and do not necessarily 5
reflect the official views or policies of the sponsoring organizations. These contents do not 6
constitute a standard, specification, or regulation. The speed data and segment information used 7
in this report was obtained from INRIX Inc. 8
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LIST OF FIGURES 1
Figure 1. NBI bridges in Burlington County, New Jersey 2
Figure 2. Functionally obsolete bridges to be studied in Burlington County, New Jersey 3
Figure 3. Monthly congestion hours for 2013 4
Figure 4. Aerial view of Bridge 03C4004 5
Figure 5. Aerial view of Bridge 03E4550 6
Figure 6. Average monthly travel speed per time of day for Bridge 03E4550 7
Figure 7. Aerial view of Bridge 314155 8
Figure 8. Average monthly travel speed per time of day for Bridge 314155 9
LIST OF TABLES 10
Table 1. Structurally deficient NBI scoring categories 11
Table 2. Functionally obsolete NBI scoring categories 12
Table 3. Functionally obsolete bridges in Burlington County, New Jersey 13
Table 4. Ten Bridges with lowest NBI Serviceability and Sufficiency Rating 14
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