7th International Symposium on Heavy Vehicle Weights & Dimensions
Delft. The Netherlands• .June 16 - 20.2002
IMPACTS OF DIFFERENT JUNCTION TYPES ON HEAVY DUTY
VEHICLES
Jussi Sauna-aho
Olavi H. Koskinen
Ministry of Transport and Communications, P.O.B. 235, FIN-00l31 Helsinki
Ministry of Transport And Communications/FINNRA, P.O.B.33, FIN-00521 Helsinki
ABSTRACT
The paper includes the impacts which four different junction types cause on heavy duty vehicles. In order to
indicate this clearly the light vehicles are surveyed, too. The impacts are estimated in quantitative units and in
money terms. The junction alternatives are: an intersection, a roundabout, an interchange with one loop ramp and
three rhombic ones and an interchange with four rhombic ramps. The type vehicles are a coach, a single unit
truck, a truck + semi-trailer combination and a truck + trailer combination and two light vehicles; it is the
passenger car and the van. The impacts are estimated by using a vehicle motion simulator based on dynamics. It is
called VEMOSIM and developed in Finland.
The VEMOSIM outputs directly the data needed for quantifying the impacts, when vehicles move through the
junctions. The impacts are: the fuel amount (and thus the variable vehicle operating costs), the emission amounts
by components (NO p CO, HC, PM and CO2 ), the time consumed, gem' changes, etc.
Based on these output data the following cost items are calculated: the variable vehicle operating costs, the time
costs and the emission costs and, additionally, the gear changes and information about the benefit distribution
between the vehicle categories. The case study concerns a 4 -leg junction of the main roads no. 5 and no. 14 in
Finland (ADT ca 8500; 89 % of light vehicles and 11 % of HDVs).
The results and the conclusions are: the best alternative is the interchange with four rhombic ramps. However, its
benefitlcost ratio is not high enough, because the construction costs are high and the traffic volume low. The
roundabout is the worst. It causes extra costs compared with the present intersection, because of decelerations and
accelerations, when the vehicles move through the roundabout. Among the different vehicle categories the greatest
impact concerns the truck + trailer combination. Especially, the fuel consumption and emissions increase
remarkably in the case of the roundabout. The VEMOSIM system is an effective tool for analyzing impacts of
different junction types.
INTRODUCTION
The origin of the study is based on the traffic growth at a junction of two main roads (highways 5 and 14) in
Eastern Finland. This is a normal junction with four legs, of which three are highways and one is a secondary road.
The highway no 5 is locating in the direction South-North-South. The Eastern leg is highway no 14, and,
especially, this has caused congestion during summer weekends. Because the present junction is of the type of the
intersection, plans have been made in order to improve the traffic situation. The junction alternatives to be studied
are: an intersection (current), a roundabout (abbreviated RA), an interchange with one loop ramp and three
rhombic ones (IC L), and an interchange with all rhombic ramps (lC D).
The paper includes the impacts which four different junction types cause on different vehicle categories. These
impacts are estimated in quantitative units and in money terms. The type vehicles are a passenger car, a van, a
coach, a single unit truck, a truck + semi-trailer combination and a truck + trailer combination. The impacts are
estimated by using a vehicle motion simulator based on dynamics. It is called VEMOSIM and developed in
Finland.
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STUDY METHOD
As a method we have used a vehicle motion simulator, VEMOSIM, based on dynamics.
The VEMOSIM simulates a motion of any vehicle. It is based on the technical characteristics of the vehicle
(engine, powertrain and gear ratios, drive resistances etc.), the road vertical and horizontal geometry and the
dri ving technique. In this case the time resolution for the simulation is 0.1 seconds. At the rate of this data updating
frequency the VEMOSIM calculates the instantaneous power need and regulates the accelerator or brake pedal
positions and gear locations according to these requirements, in other words simulates the real engine operating
state ten times per a second.
The VEMOSIM outputs directly the data needed for quantifying the impacts, when vehicles move through the
junctions. The impacts are: the fuel amount (and thus the variable vehicle operating costs), the emission amounts
by components (NO x , CO, HC, PM and CO2), the time consumed, gear changes, etc.
Because all individual vehicles passing through the junctions cannot be simulated, a representative sample of
different vehicles are selected for the vehicles categories. In this context they are called the type vehicles.
INPUT DATA
For the simulation concerning each type vehicle three different types of input data are needed: 1) the technical
characteristics of the type vehicles, 2) the vertical and horizontal alignment of the different routes (continuously)
and 3) the driving technique that is mainly composed of the goal speed pattern (meter by meter).
In order to calculate the total impacts (all vehicles passing the junctions), the traffic volumes by the vehicle
categories and traffic routes (4
* 3 = 12) must be known, see table 1. The cross section traffic volumes by road leg
and vehicle categories are seen in table 2.
The goal speed pattern is in general an array of the instantaneous speed that the driver tries to maintain at any part
of the route to be driven. The current speed limit values naturally determine the most of the patterns, but for
example at turns (left and right) as well as at roundabouts those speed limit values (80, 60 and 50 kmlh) cannot be
maintained. In those cases the goal speed is 20 .. .30 kmlh unless the vehicle stops. But sometimes the vehicles are
obliged to stop when swerving the priority traffic. Then the goal speed is instantaneously 0 kmlh. In the goal speed
patterns the share of stopping vehicles has been taken into account. For each route and junction type alternative
two patterns have been determined, the one for the non-stopping vehicles and the other for the stopping vehicles,
see table 3.
The traffic is composed of six vehicle categories, which are represented by the respective type vehicles. These are:
Vehicle category
Abbreviation A verage mass
kg
Passenger car
1200
Van
Bus & coach
P
V
2300
C
15000
Single unit truck
T
20000
Truck + semi-trailer
TS
35000
Truck + trailer
TT
50000
The detailed vehicle technical data are not presented here.
434
IMPACTS STUDIED
The impacts caused by the different junction alternatives are surveyed both as quantitative and as economical. The
results are presented as differences compared to the present junction type (intersection). An example of a drive
simulation through a roundabout is shown in figure 1.
The most important quantity is the fuel consumption. On the basis of the fuel consumption the all variable vehicle
operating costs are determined, too .
The variable operating costs are composed of the following items:
- fuel costs
- lubricant costs
- repair and mai ntenance costs
- tyre costs
In this study the lubricant, repair & maintenance and tyre costs are assumed to change in the same ratio as the fuel
consumption (Wehner's principle). These costs are presented both at the market price (including indirect taxes) and
at the production cost price (excluding indirect taxes).
The used time is surveyed, too. The time has also shadow unit prices for the different vehicle categories. In this
respect there is no difference between the market price and production cost price.
The pollutant emissions to be surveyed are:
- nitrogen oxides (NOJ
- carbon monoxide (CO)
- hydro carbons (HC)
- particulate matters (PM)
- carbon dioxide (C02)
These pollutants also have shadow unit prices, by which the emission amounts have been converted to monetary
values.
RESULTS
Fuel amount
The changes in the fuel amount are shown in figures 2 - 3. Concerning the different vehicle types in this respect the
truck + trailer plays a dominant role. Concerning the junction alternatives the roundabout increases remarkably
fuel consumption while the both interchange types decrease it.
Nitrogen oxides
The changes in the NO x amount are shown in figures 4 - 5. As regards the nitrogen oxides the same conclusions as
the ones regarding fuel consumption can be made. However, the truck + trailer seems to have an emphasized role.
The time changes are shown in figures 6 - 7. In this respect the passenger car is dominant because of its high traffic
volume and, in addition, to the highway 5 (South - North - South) the highway 14 (East - South) has some
significance.
Variable vehicle operating costs
The variable vehicle operating costs at cost production price are shown in figure 8 and the ones at market price in
figure 9. According to the definition of the variable vehicle operating costs (Wehner's principle) the impacts on
them are in the same relationship as the impacts on fuel consumption.
435
Total costs
The changes in the total costs are shown in figures] 0 and] ]. Concerning the different vehicle types in this respect
both the passenger car and the truck + trailer play a dominant role. Concerning the junction alternati ves the
roundabout increase total costs of both the passenger car and the truck + trailer. The interchange with four rhombic
ramps is the best solution and decreases the total costs for all vehicle categories.
CONCLUSIONS
The best junction type is an interchange in general, because it causes savings in the vehicle operating, time and
emission costs for all vehicles.
In this case the interchange with the four rhombic ramps brings the most benefits to the traffic.
On the contrary, the roundabout is the worst because it only increases vehicle operating, time and emission costs
for all vehicles. In general, the roundabout should be avoided as junctions of main roads.
The VEMOSIM system is an effective tool for analysing impacts of different junction types.
436
TABLES & FIGURE
Table 1- Traffic volumes ADT [veh/d] at the junction
1
2
3
4
5
6
7
8
9
10
11
12
DIRECTION
P
V
C
T
TS
TT
TOT
SOUTH-WEST
131
1060
1710
126
124
131
226
1060
126
1710
124
226
15
118
190
14
14
15
25
118
14
190
14
25
3
24
41
3
3
3
7
24
3
41
3
7
4
32
38
4
4
4
8
32
4
38
4
8
0
40
6
0
0
0
3
40
0
6
0
3
4
168
43
4
4
4
19
168
4
43
4
19
157
1440
2027
151
149
157
287
1440
151
2027
149
287
SOUTH-NORTH
SOUTH-EAST
WEST-NORTH
WEST-EAST
WEST-SOUTH
NORTH-EAST
NORTH-SOUTH
NORTH-WEST
EAST-SOUTH
EAST-WEST
EAST-NORTH
Table 2- Cross section volumes ADT [veh/d] at the junction
1
2
3
4
LEG
P
V
C
T
TS
TT
TOT
SOUTH
5802
761
2822
4119
645
85
314
458
134
18
67
101
146
24
87
99
91
0
84
17
428
24
381
131
7246
912
3755
4925
WEST
NORTH
EAST
Table 3- Proportion of stopping flows and average waiting time at the junction
ALTERNATIVE
1
2
3
4
5
6
7
8
9
10
SOUTH-WEST
SOUTH-NORTH
SOUTH-EAST
WEST-NORTH
WEST-EAST
WEST-SOUTH
NORTH-EAST
NORTH-SOUTH
NORTH-WEST
EAST-SOUTH
11
EAST-WEST
12
EAST-NORTH
1
2
4
3
STOP
TIME
STOP
TIME
STOP
TIME
STOP
TIME
%
s
%
s
%
s
%
s
22
0
0
100
100
100
35
0
0
100
100
100
6
0
0
2
2
2
6
0
0
2
2
2
8
8
8
8
8
8
8
8
8
8
8
8
4
4
4
4
4
4
4
4
4
4
4
4
45
0
24
65
30
30
20
0
20
0
0
0
6
0
2
35
0
20
30
0
0
25
0
25
20
0
0
6
0
2
437
10
0
4
2
0
1
0
0
0
10
0
0
10
0
1
2
0
0
SISU E 14 1- 475
120
110
f(OAD : L 0 ;: B:A
SPE ED [ m/l-] I
FUE L AI"! PUNT [clJ
100
I
/
/'
gl2l
~~
[(
80
70
60
~
30
10
+1121
-3 5
+5
+0
-5
- 10
V
-3
- 2 ,5
~Jl
-2
- 1 ,5
-1
0
J
V
. . . v----
/~
J
.5
~
/"'-
GRAD.
- ,5
} jj
JJ
l/
/
t/
I ;/
//
I
V
40
\
\
/
50
20
/1
j
1
1. 5
~
~
'J'
[;l.J
I
2
"'---
!
2.5
.3
,~
/,
I
DISTANCE [km]
Figure 1 - An example of a drive simulation through a roundabout
Type vehkle:
truck + trailer
South - North
Route:
COM PARI50N BETWEEN ALTER NA TI UE5
200 ,----------------------------------------------------------------FUEL AMOUN T [ lid]
- 150
~------~--------~--------~------~--------~--------~------~
P
IJ
c
T
T5
TT
Figure 2 - Fuel amounts by vehicle categories at different junction types vs intersection
438
3.5
ROUNDABOUT US, INTER5ECTION
388
FUE L AMOUN T [ lid]
250
280
150
100
50
o
P
l)
T
C
T5
TT
ALL
Figure 3 - Fuel amounts by vehicle categories at roundabout vs intersection
COM PAR I 50N BETWEEN ALTERNAT I UES
9008
ND x [g / d J
8008
_ __
7000
6000
5008
40013
3121121121
212100
1008
13
-112100
-21211210
- 301218
- 4008
- 512100
P
l)
T
C
T5
Figure 4 - NO x amounts by vehicle categories at different junction types vs intersection
439
TT
____-'-'- L
ROUNDABOUT US , INTERSECTION
112100121
NDx [g / dJ
900121
800B
700B
500121
500121
40BB
300B
200121
1121013
B
P
l)
T5
T
C
TT
ALL
Figure 5 - NO" amounts by vehicle categories at roundabout vs intersection
COMPARI SON BET WEE N AL TE RNATIU E5
13BB
TIME [min/dJ
120121
110B
100121
----------------------------------------------------------- -. .~
__________________________________________________________
90B
8013
70B
6BB
50121
40B
3 0121
20B
lBB
121
- IBB
- 20121
P
l)
T
C
T5
TT
Figure 6 - Time consumed by vehicle categories at different junction types vs intersection
440
L
-L~~ D
ROUNDABOUT liS , I NTER5 ECTIoN
16138
in/ d]
15130
14138
1300
12130
11138
11308
900
800
7130
608
500
400
300
208
100
0
P
C
U
T
TT
T5
ALL
Figure 7 -Time consumed by vehicle categories and their sum at roundabout vs intersection
COMPARI50N BETWEE N ALT ERNATIlIES
2138
FUEL+LUBRICANT+REP&MAINT , +TYRES [EUR / d J (e xcluding tax e5 )
•
~
150
__________________________________________________________________
RA
~"-ll-
D
L
le D
- 1138
- 150
' p
c
T
T5
TT
Figure 8 - Variable vehicle operating costs at production cost price by vehicle categories at different
junction types vs intersection
441
COMPARISO N BETWEE N ALTER NA TI UES
208
F UEL+LUBRICANT+REP&MA I NT . +TYRES [EUR / dJ (i nc l uding tax es )
_ _ _ ........~--'-'-L
150
108
50
- 50
- 108
- 150
c
P
T
T5
TT
Figure 9 - Variable vehicle operating costs at market price by vehicle categories at different junction types
vs intersection
CO MPARISON BETWEE N ALT ERNA TI UES
358
F UEL+ LU BRICANT+REP&MAINT +T YRES+TI ME+ NO x+CO+HC+PM+C02 [EUR/ d J (e x c l uding ta x es)
308
L
258
D
200
158
108
58
o
- 58
- 108
- 150
-200
P
IJ
c
T
T5
TT
Figure 10 - Total costs at production cost price by vehicle categories at different junction types vs
intersection
442
COMPARI50N BETWEEN ALTE RNAT I UES
358
FUEL+LUBRICANT+REP&MAINT.+TYRES+TIME+NO x+CO+HC+PM+C02 [EU R/ dJ (including ta x es )
308
L
258
D
200
158
108
58
- 58
- 108
- 150
- 200
p
IJ
c
T
TS
TT
Figure 11 - Total costs at market price by vehicle categories at different junction types vs intersection
443
444