Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Report
congestion pricing systems will remain at current levels. Agencies will report performance on
some facilities but will lack sufficient data to manage the overall system. High energy prices will
keep congestion somewhat manageable. Congestion in this scenario will still be the worst of the
three scenarios. In terms of technology, ramp metering will still be in use. Advanced traffic signal
algorithms will improve arterial traffic flow but congestion will still occur during peak periods.
There will be a need for widespread automated enforcement of speed, red light running, ramp
meters, and toll evasion. Automated Highway Systems will not be fully implemented, requiring
some motorists’ awareness while driving. A great deal of traveler information will be provided but
the overall level of information will not be as good as that provided in the optimistic scenario due
to fewer probe vehicles. Luxury and mid-priced vehicles will have active and passive driver
assistance systems but lower priced vehicles will still lack the latest systems.
The slower economy will mean that more people will still use older vehicles without the latest
safety systems. For these reasons, this scenario will have the highest crash rates and the highest
levels of non-recurring congestion. It will therefore be the most unreliable scenario. Because of the
high cost of fuel, telecommuting will be popular but it will not be done on a scheduled basis (much
as it is done today). It will not be practiced in response to traffic fluctuations as predicted in the
optimistic scenario. Incident response advances will not be noticeable in the same way as in the
mediocre scenario. It will be difficult for agencies to devote enough resources to both incident
response and disaster management, since crash rates will be high and disasters will be frequent.
Some weigh stations and ports of entry will have inspection technology that allows for by-pass at
freeway speeds. Logistics efficiency and JIT will not be emphasized because many companies will
be in a survival mode and because the network will be congested - thereby reducing freight
reliability. Security monitoring of major facilities will be implemented and limited hazmat tracking
will occur.
BASELINE AND ALTERNATIVE FUTURES STRATEGY ASSIGNMENT
In order to establish a reference point for the implementation of the key strategies, the impact of
each alternative future scenario on the sources of congestion was ranked as low, medium, or high.
The information provided in Table 5.1, Table 5.2, and Table 5.4 (see Chapter 5) served as a basis
for the ranking process. The results of this process are shown in Table 7.1.
Table 7.1 Impact of Alternative Futures on the Sources of Congestion
Sources of Congestion
Optimistic
Scenario
Impact based on Future Scenario
Mediocre
Scenario
Pessimistic
Scenario
Traffic Incidents High Medium Low
Weather Low Medium High
Work Zones Low Medium High
Fluctuations in Normal Traffic/Special Events Medium High Low
Traffic Control Devices Medium High Low
Physical Bottlenecks High Medium Low
As shown in Table 7.1, traffic incidents and physical bottlenecks are expected to be significant
sources of travel-time unreliability in the optimistic scenario. The decline in reliability from these
sources will be mitigated through safety gains achieved from the extensive use of ITS technologies
aimed at improving traffic operations. For the mediocre scenario, traffic control devices and
A CONCEPT OF OPERATIONS Page 108