This is part of a series of stories examining the decision to build a rail transit line in Honolulu.

Cliff Slater says the Final EIS gives no reasonable explanation why the city removed Zipper Lane in the Managed Lane alternative.

Planners considered a number of alternatives for solving traffic problems but examined only four extensively — Doing Nothing; a Transportation System Management that includes enhanced bus service; Managed Lanes and a Fixed Guideway System (Rail Transit).

Slater believes there was insufficient study of alternatives and that the review of the Managed Lane alternative was altered without explanation.

Managed Lanes can best be visualized by imagining an elevated two-lane highway built above freeways between Waipahu and Downtown Honolulu. This elevated freeway would be used by buses, vanpool and carpool vehicles, high-occupancy cars and single-occupant vehicles willing to pay a toll.

Planners looked at two options for Managed Lanes, one of which would feature traffic going in both directions and another that operated in a single direction depending on the time of day. They settled on the “reversible,” or single-direction alternative, because of cost.

Slater contends analysis of Managed Lanes was flawed because it did not keep the Zipper Lane – that extra lane that is created on existing highways when zipper-like barriers are placed in contra-flow lanes during the morning rush hour.

He says if two Managed Lanes are added above the freeway and the Zipper Lane is discontinued, the Managed Lanes option would have the net effect of adding one lane instead of two.

Slater says a Managed Lane alternative with a Zipper Lane would be a viable option in terms of traffic volume on the H-1 freeway and other roads. By his calculation, general purpose traffic volume on the H-1 freeway and other roads during the morning commute would be 20,322 vehicles per hour with Managed Lanes and a Zipper Lane operating.

Traffic planners looked at a number of traffic measurements to compare the various options, including peak rush-hour traffic volume along the H-1, Moanalua Road and Kamehameha Highway in Aiea. When these numbers are totaled you get a metric planners call Total General Purpose Traffic.

Slater contends the reversible Managed Lanes Alternative with the Zipper Lane reinstated is superior to Rail with respect to Total General Purpose Traffic during the morning rush hour.

Categories Capacity – Vehicles per Hour Existing Volume 2003 Managed Lanes with Zipper Lane* Rail*
Total General Purpose Traffic 14,650 10,960 20,322 21,120
HOV/Zipper 3,800 3,300 4,923 4,980
Managed Lanes** N/A N/A 3,457 N/A
Total All Traffic 18,450 14,260 28,702 26,100

*Year 2030
Source: Table 3-12 Alternatives Analysis; Cliff Slater

The above table shows Managed Lanes with a reinstated Zipper Lane beats out Rail in terms of Total General Purpose Traffic.

But on another measure used by Slater, Total All Traffic, Managed Lanes come in second place.

Total All Traffic includes General Purpose traffic in regular lanes on the H-1, vehicles using the Zipper/HOV lane, and traffic in Managed Lanes – would total 28,702 vehicles per hour.

That’s more than the 26,100 for the Rail Transit scenario.

As such it is the city’s thesis that travel times may be reduced for some commuters with Managed Lanes, but for others the time savings will be reduced by bottlenecks around the entrance and exit ramps to the elevated lanes.

Slater, however, notes the higher total traffic numbers don’t necessarily mean congestion would be worse. He points to work done by Panos Prevedouros, a former Honolulu mayoral candidate and University of Hawaii professor who specializes in traffic and traffic engineering.

Prevedouros, who ran on the promise that he would kill the rail project, has proposed ways to mitigate congestion in Downtown Honolulu. Slater says these and other measures should have received more serious study by the city. He says they would show Managed Lanes as a worthy option.

In conclusion, Slater’s point that the Final EIS doesn’t give a reasonable explanation for the removal of the Zipper Lane from the Managed Lane alternative is technically correct. There is no mention of why the Zipper Lane was excluded from the Managed Lane option.

But the Final EIS, released to the public in June 2010, wasn’t required to delve extensively into all alternatives. It only was prepared to look at the Fixed Guideway versus the Do Nothing scenario.

In a June letter to Slater, Wayne Yoshioka, director of the city’s Department of Transportation Services, noted the Zipper Lane was removed from the Managed Lanes scenario during the Alternatives Analysis in 2006.

He wrote the Zipper Lane was eliminated for several reasons, including the need for more H1 freeway lanes in coming years to handle traffic heading in the reverse direction from commuters.

More analysis tomorrow in Part 2.