Thursday, July 17, 2008

How good can it get if traffic lights are optimized?

I summarize for you the results published in the most recent issue of the Journal of the Institute of Transportation Engineers (June 2008.)

After decades of neglect, the city of Balimore, Maryland decided to replace 1,300 old controllers and then optimize the traffic lights in the central business district and arterials that lead to and from it. The focus of detailed data collection and optimization was 425 intersections with traffic lights, of which 250 were in downtown and the rest on gateway arteries. Ten gateway arteries were identified numbering 175 traffic lights along their 30.5 miles of total length.

There are interesting similarities between Baltimore's past experience and Honolulu's current experience. I have been complaining that all traffic lights along Vineyard Boulevard run a very long 165 second cycle. That is exactly the old cycle in some of Baltimore's arterials.

What did this cost for the city of Baltimore? $762,500. How much did it save in delays, stops, fuel consumption, carbon monoxide and nitrogen oxides? $32,666,123. For a cost-benefit ratio of 43 to 1.

Delays (an engineering term for wasted time) dropped from 11,351 hours to 7,952 hours per day resulting in a value of time savings of $26,132,499. A drop of 30% means that a 20 minute trip on Honolulu arterials could be reduced to less than 15 minutes.

The article concludes as follows: "the benefits derived from this project proved that signal timings should not be compromised in the field, and an effort like this to perform city-wide signal timing optimization is well worth the money. The benefits outweighed the costs in less than three months and exceeded the expectations of city and public officials."

If the people vote in favor of rail and you win the election, how do you handle this?

John H. sent me this question. Here is my answer:

I will not support Hannemann's six-plus billion dollar 34 mile fully elevated heavy rail.

But I will respond directly to people's vote by redesigning for a true light rail system (planners and architects prefer at-grade stations), developing other alternatives, doing an honest alternatives analysis with full disclosure of costs, and letting people decide which alternative to build. It will take about 10 months to have honest estimates of benefits and costs. Then in one year we can start with the option that people choose based on quality information.

At the present time, the community cannot decide on rail with the information that Hannemann has put forth. What we have been given is a sales brochure with a promotion campaign. We need at least a "Consumers Report" level of analysis in order to decide.

If this leads to light rail, then I will support light rail as long as the majority of the public also supports the extra taxes that will be needed for its development and operation.