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OCR for page 24
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Very easy; 3; 7%
Difficult; 8; 18%
Easy; 13; 30%
OK; 20; 45%
FIGURE 5 Difficulty in understanding working principles of an ATCS.
on their own (in-house) expertise. The others contract out to OPERATIONS
ATCS vendors either for all tasks (10%) or only for major mod-
ifications in the operations of their ATCS (29%). It is inter- The deployment of an ATCS can bring significant benefits to
esting to note that ATCS users with larger ATCS deployments traffic performance on the network where it is installed and
(50 or more intersections under an ATCS) are more inclined requires a commitment to staffing for operations and mainte-
to use their own expertise (70%). Level of expertise on an nance. ATCSs are often presented as a labor-saving alterna-
ATCS that stays within an agency tends to increase with the tive to conventional traffic control, as the signal timing plans
size of the ATCS installation and the financial resources avail- do not need to be developed on a regular basis. However, an
able to keep that installation running. ATCS is not a hands-off type of system.
When it comes to building in-house expertise, 57% of inter- ATCSs are complex in operation, and it is believed that
viewed agencies would like to acquire such expertise to fully traffic engineers need at least four to six months to acquire a
utilize the potential of their ATCSs. It does not appear that general understanding of these systems, whereas an experi-
these agencies would have problems securing funding for enced signal timing engineer needs about two months. These
such additional training programs. Only 2% of the agencies estimates indicate only the time needed to understand the
believe that such an educational effort would be too expen- system and not the time needed to become proficient. It may
sive. Seven percent of the ATCS users believe that there is no take years for a signal traffic engineer to acquire hands-on
interest within their agencies for such a training program. experience and become proficient with the system. For smaller
More specifically, 12% of the all interviewed agencies rec- agencies that run small-size ATCS deployments, retaining
ognize that such a lack of interest for full in-house expertise the ATCS-proficient staff becomes the most important ATCS-
on the ATCS is associated with the concept that their ATCSs related issue.
control only a small percentage of traffic signals under their
jurisdiction. Therefore, the ATCSs do not attract enough atten- Approximately 56% of the surveyed ATCS users find that
tion from their agencies to warrant the full in-house exper- these systems are more demanding for operations than con-
tise. Another 24% of the respondents are unable to provide ventional traffic control systems. Nine percent of that 56%
resources for such training because of insufficient funding. In find ATCSs to be much more demanding than other sys-
general, the problem is not so much finding the resources for tems. Conversely, approximately 21% of ATCS users believe
the training itself as in having enough individuals to attend the that ATCSs are less demanding. The remaining 23% per-
training and take responsibility for the full in-house expertise ceive ATCSs as similar to their other systems. These answers
on the ATCS. are somewhat correlated with how the agencies operate and
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25
maintain the systems. An agency with enough resources to · If traffic demand is light the cycle was lower and more
hire outside consultants for the smallest operational tasks of accommodating.
an ATCS may find it easier to operate their ATCS because it · It does well when traffic flow is incremental, not when
is mostly operated (everything but every-day operations) by there are turbulent fluctuations in volume and demand.
a consultant. · Coordination between signals, handling special events,
changes in traffic volumes and patterns, and tourist area
Sixty percent of the interviewed agencies reported that traffic.
they do not have enough staff to operate and maintain their · Ability to quickly respond to traffic fluctuations.
ATCSs to the fullest potential. Many agencies reported that · Covers special sequence operations.
it is much easier to find funding for capital investments, such · Responds well to large volumes of traffic exiting on side
as an ATCS deployment, than for regular operations and streets that do not happen according to a regular sched-
maintenance of the existing technologies. A particular notion ule (e.g., a themed water park emptying as the result of
about ATCSs exists that implies that once they become oper- a thunderstorm).
ational they do not need much maintenance. This might be · Provides detailed information of traffic signal from cen-
one of the major reasons that some of the ATCS deployments tral office.
are understaffed. The reality is quite opposite; ATCSs need · Maximizes throughput.
more high-expertise maintenance than regular traffic control · Network control is delivered effortlessly.
systems. If such a need is not recognized by the agency there
is a considerable chance that the ATCS will underperform On the other hand, the ATCS does not always perform
and eventually even be replaced by a conventional traffic sig- as expected. There could be many reasons for this under-
nal system. The respondents' answers on their annual budgets performance; at times, these systems are not fine-tuned and
for ATCS operations agree with the previous responses about customized as needed. The literature review did not find
the shortage of staff. About 63% of the interviewed agencies any field evaluation studies that would show the benefits
do not have an annual budget (for operations and maintenance
derived from the fine-tuning of an existing ATCS deploy-
of traffic signals) that is large enough to cover expenses for
ment. There have been few studies where suboptimal deploy-
full utilization of their ATCSs.
ments of an ATCS are investigated (Taale et al. 1998;
Jayakrishan et al. 2000); however, evaluations of customiz-
ATCS vendors and consultants need, on average, approx-
ing well-operated systems are rarely documented. With so
imately 100 person-days to make an ATCS operational. How-
many operational parameters that can be adjusted in every-
ever, this number also varies considerably among agencies.
day ATCS operations one would need to explore, if not to
Some of the systems required as few as ten days to become
optimize, the values of those parameters to achieve optimal
operational, whereas others required as much as an entire
ATCS operations.
year. In general, most ATCS users (80%) were satisfied with
the technical support from vendors and consultants. Reasons
not to be satisfied were primarily related to the costs of the An ATCS sometimes does not perform as expected because
technical support (32%) and that some ATCS vendors do not initial expectations are set too high. When advertising an
provide local expertise to some of the ATCS users (34%). ATCS to potential customers, ATCS vendors at times over-
The other major complaints were that ATCS consultants have state the abilities of these systems. This situation sometimes
only a few hands-on experts (often only one) who cover an raises expectations concerning the ATCS, which in turn can
entire nation or that the vendors were reluctant to modify or lead to disappointment in their performance if the existing
improve the ATCS to better fit the user's needs. Again, these traffic problems cannot be solved (solely) by its deployment.
problems can be associated with the number of ATCS users Although the deployment of ATCSs can undoubtedly pro-
in the United States (or in the world). ATCS vendors and vide an improvement to traffic flows under normal (under-
consultants do not find it profitable to train more than a few saturated) traffic conditions, it need not be considered a cure
individuals on the ATCS or to customize software for a for capacity constraints. If the expectations for the system are
single user. If more agencies were to use ATCSs these prob- too high, there is a chance that the system will not be per-
lems would be expected to diminish. ceived as successful. This is especially true when observed
from a single traveler's perspective. The individual user's
Achievement of operational benefits from ATCSs is a benefits of an ATCS (or any other system) are generally lim-
major reason why these systems are installed. Outcomes of ited; however, when multiplied by the number of vehicles
the following operational features are recognized as the most using the facility, they may bring significant savings to the
important benefits by ATCS users: motoring public. Surveyed ATCS users recognized the fol-
lowing operational issues:
· Responds well to emergency vehicle preemption and
traffic congestion resulting from crashes, clears back- · Poor operation for traffic demand surges such as those
ups quickly. experienced during unplanned and planned special
· Response to day-to-day and TOD fluctuations in demand. events.
