Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Report
The travel-time expectations are based on a combination of personal experience and information
from on-line mapping utilities (such as MapQuest) and GPS devices. Further, if the trip is
undertaken in a familiar area, travelers do factor in congestion while estimating travel time. For
some participants, reliability was simply not encountering congestion. These people did not like
“being stopped when they are supposed to be travelling.” One participant indicated (in the context
of freeway travel) that “if you are taking more than two minutes per mile (30 mph), you should
probably be looking for an alternate route” suggesting that lower than anticipated speeds is also a
measure of unreliability.
Freight Movers
For freight movers with delivery windows of less than 30 minutes, reliability is related to the
frequency that the experienced travel time is within +/- 15 minutes of the expected travel time.
Therefore it is fair to say that travel times do not need to be predicted with any more certainty than
+/- 15 minutes. However, there are two main issues with this:
• Narrower windows are not required, in part, because they are currently unattainable.
Carriers are not willing to promise delivery windows they know they cannot generally
make; and
• For carriers that make many deliveries in one day, a series of longer than average travel
times compound, making it difficult to identify how reliable an individual trip needs to be.
The focus group discussions suggest that travel-time reliability is NOT an issue that has made it to
the strategic level, and therefore is not relayed to the shipper’s activities in moving freight. This
leaves the carriers with little flexibility from the shipper and forces the carrier to manage traveltime
reliability. This is consistent with the responses from carriers. When asked about their
primary transportation concerns, unlike the carriers, shippers mentioned oversize/overweight
restrictions and the railroads. For instance, Boeing is a manufacturer of very expensive goods that
relies on skilled labor and has a long history of activity in the Puget Sound area. Concerns about
the lack of reliability in travel times have not become so problematic that they have been addressed
at the strategic level within the company. Given their cost of goods, and their JIT operations, they
are willing to bear the relatively small cost of having trucks idle. They are driven by service and
quality. This means that they will pay more for good service, like FedEx. Solutions typically
involve adding cost to the carrier in increased wait times.
TRAVEL-TIME RELIABILITY IMPORTANCE
This section depicts the importance (high, medium, low, or unclear) of travel-time reliability for
each user group according to the outcome of the focus group meetings.
Passenger Travelers
Research has shown that travel-time reliability is very important to passengers. In fact reliability
(or consistency) in travel times appears to be even more important than the magnitude of the travel
times. (“You expect that it will take 15 minutes and it takes 15 minutes – it does not matter that it
was a mile for 15 minutes if you anticipated it.”) If it is known in advance that the travel times are
going to be long, then the users are able to plan for it. However, if the travel time turns out to be
longer than expected, then it could disrupt their plans in different ways depending on the nature of
the trip. Finally, it is useful to note that people do not appear to be overly concerned about travel
times being less than the anticipated values.
This research effort has demonstrated that the actions taken by the travelers to deal with
unreliability and the consequences when the travel time turns out to be greater than the anticipated
value were discussed for seven trip purposes. The importance of travel time reliability for the
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