|
Sub-problem 1a - Page 3 of 9 |
ID# C201A03 |
Sub-problem 1a: Maxwell Drive PM
Peak Hour - Existing Conditions
Arrival Type
Changes
Now let’s consider a
parametric analysis: what happens if the
arrival type changes from 2 to 1,
3, or 5 for the eastbound approach? For example, if we introduce
coordination that improves eastbound progression, the arrival type could
become 3, 4, or 5. If we make the progression worse by focusing the westbound flows, assuming there’s a tradeoff, it could
become 1. From Exhibit 2-9 we can
see that if the progression gets better, the eastbound delays could drop
as low as 2.2 seconds for the left and 0.6 seconds for the through. (Dataset
2 shows inputs for the arrival type 3
and Dataset 3
shows inputs for arrival
type 5.) These
values are a small fraction of the base case. The average queue lengths
could drop to 0.5 and 0.8 vehicles respectively. This urges an examination
of coordination options. (Refer to
Dataset
4 to see the details for arrival type 1).
From Exhibit 2-9 we can also see that if the coordination gets worse (arrival
type 1), the eastbound left-turn delay could increase to 27.2 seconds.
That’s 45% more than the base case of 18.8 seconds. For the through
movement, a
similar increase could take place, from 5.3 to 8.0 seconds, a 50%
increase. The average queue lengths could grow from 4.2 to 5.2 vehicles
for the through movement (24% increase) and 1.8 to 2.3 vehicles for the left-turn
movement (28%
increase). In fact, the latter situation could be a problem. The left-turn
storage capacity is only 5 vehicles and the 95th-percentile
queue length (not shown in the table) is 4.7 vehicles; so with arrival
type 1, we’re nearly at that limit.
|
Exhibit 2-9.
Maxwell Drive Effects of Variations in the Eastbound Arrival Type |
|
Data-set |
EB Arrival Type |
Heavy Vehicles |
Phase Skip |
Signal Timing |
Performance
Measure |
EB |
WB |
SB |
OA |
|
L |
T |
R |
Tot |
L |
T |
R |
Tot |
L |
T |
R |
Tot |
|
1 |
2 |
Yes |
Yes |
Base |
Delay |
18.2 |
5.3 |
- |
7.7 |
- |
16.7 |
16.7 |
17.3 |
- |
20.8 |
18.5 |
13.7 |
|
Queue |
1.8 |
4.2 |
- |
- |
- |
9.9 |
- |
2.4 |
- |
2.7 |
- |
- |
|
2 |
3 |
Yes |
Yes |
Base |
Delay |
11.9 |
3.5 |
- |
5.0 |
- |
16.7 |
16.7 |
17.3 |
- |
20.8 |
18.5 |
12.7 |
|
Queue |
1.3 |
2.9 |
- |
- |
- |
9.9 |
- |
2.4 |
- |
2.7 |
- |
- |
|
3 |
5 |
Yes |
Yes |
Base |
Delay |
2.2 |
0.6 |
- |
0.9 |
- |
16.7 |
16.7 |
17.3 |
- |
20.8 |
18.5 |
11.2 |
|
Queue |
0.5 |
0.8 |
- |
- |
- |
9.9 |
- |
2.4 |
- |
2.7 |
- |
- |
|
4 |
1 |
Yes |
Yes |
Base |
Delay |
27.2 |
8.0 |
- |
11.5 |
- |
16.7 |
16.7 |
17.3 |
- |
20.8 |
18.5 |
15.1 |
|
Queue |
2.3 |
5.2 |
- |
- |
- |
9.9 |
- |
2.3 |
- |
2.7 |
- |
- |
Discussion:
If we were to do a parametric study of arrival types for the
westbound approach we’d find similar trends. The analysis would be
useful, because better coordination ought to be possible with the signal
at Clifton Country Road. What we’d need is a common cycle length and
appropriate splits and offsets. It would also be useful to see if flow could
be improved if we closed the exit from the fast food restaurant just east
of the stopbar or did something to the intervening unsignalized
intersection (with Old Route 146) that produces mid-block traffic that
disrupts progression. We’ll look at these issues when we do
Problem 6, the arterial analysis.
[ Back ] [ Continue ]
to Sub-problem 1a
