Getting there on time, all the time

Reliable and effective arterial roadways are necessary for ensuring a high level of mobility in urban areas and to reduce environmental pollution caused by vehicle idling. However, a key issue that communities and urban commuters face is the continuous rise in the level of urban traffic congestion and associated pollution. For example, it has been found that, because of increasing congestion, Americans traveled an extra 8.8 billion hours in 2017 resulting in a total congestion cost of US$166 billion.

Urban congestion has been a growing problem, however, there are opportunities for innovation and improvement for reliable and sustainable arterial roadway systems. Such research studies, with which I am very familiar, i.e., intelligent infrastructure, transportation and mobility, and environment and health. Nevertheless, roadway performance reliability studies and especially travel time reliability (TTR) have recently received considerable research interest. For example, the Fixing America's Surface Transportation Act and the Moving Ahead for Progress in the 21st Century Act mandate that all state Department of Transportation regularly report the performance reliability of the national highway system.

1. The simplest way to make sure to get to work on time all the time is to collect travel time data everyday.

2. First, record your start times and end times from origin to destination everyday. Do this for over from 6 months to a year. I prefer a year because all the unexpected congestions or delays caused by incidents, weather, work zones, or demand fluctuations would have been covered.

3. Substract the start time from the end time for each trip to get the travel times over the study period (e.g. a year)

4. Plot a travel time distribution and determine the following:

   1. Measures of central tendency e.g., mean, median

   2. Measures of dispersion e.g., standard deviation, interquartile range

   3. Percentiles e.g., 95th percentile travel time.

5. The difference between you mean travel time and the 95th percentile travel time is your Buffer index. This tells you how much time you need to add to the mean travel time to always get there on time 95% of the time.

6. Hence, you can decide to schedule a trip start time so as to always get to your work or destination on time all the time.

7. This can reduce the congestion level - avoid unnecessary delays in traffic rather than using that time for other productive use.