The news that NYSDOT was “tiering” the Tappan Zee Bridge/I-287 corridor project into separate phases was surprising enough (MTR ran stories on the announcement of the split and on an ominous precedent). But a scoping update document (PDF), made public by the study team last week, contains additional surprises. The NYSDOT project involves the replacement or rehabilitation of the Tappan Zee Bridge and the construction of mass transit along the 30-mile I-287 corridor between Suffern and Port Chester.

Besides the tiering of the project, the biggest change is the addition of several new transit options to the four transit alternatives evaluated during the Alternatives Analysis — full corridor bus rapid transit (BRT), full corridor commuter rail, Rockland-Manhattan CRT with Westchester light rail, and Rockland-Manhattan CRT with Westchester BRT. Intriguingly, the study now includes two enhanced full corridor BRT options with a routing alignment more completely along I-287 in Westchester. (Significant portions of the original full corridor BRT alternative would operate in bus lanes on Route 119 in Westchester.) One enhanced BRT option would run buses entirely on dedicated busway throughout Westchester, as well as provide separate service through bus lanes in White Plains.

In a move advocated for by the Tri-State Campaign, the study team has also resurrected a combination of full corridor BRT and Rockland-Manhattan commuter rail. This option was dropped from the Alternatives Analysis although it had the highest projected ridership of any alternative (see MTR # 551).

Another big change to the project is the inclusion of three bridge rehabilitation designs that can accommodate transit and bike/pedestrian facilities. (Previously, all transit alternatives included the replacement of the Tappan Zee Bridge.) However, calling the new bridge designs “rehabilitation options” may be somewhat of a stretch, as two of the options include the construction of a sister structure, while the third “rehabilitation option” is a widening of the Tappan Zee.

One odd omission from the scoping documents are high-occupancy toll (HOT) lanes — carpool lanes which single-occupancy vehicles can pay a toll to access for a congestion-free ride. Though HOT lanes appear in some document graphics, the text refers only to ordinary HOV (high-occupancy vehicle) lanes. HOT lanes are an innovative way to maintain congestion-free access across the bridge and raise transportation revenue, and the project team should continue to be study them. Regular carpool lanes, on the other hand, are frequently underused and there is often public pressure to convert them to general purpose lanes (see MTR #s 178, 245, 547 and others).

Despite the recent flurry of news on the Tappan Zee project, the study’s cumulative delays have added up and Hudson Valley residents will have to resign themselves to another extended timeline. The study team will select a transit mode by May, but circulation of the draft environmental impact statement is not expected until September 2009, with a record of decision coming in the spring of 2010.

Next week, the Tappan Zee study team will hold public meetings on the changes to the project in Westchester and Rockland Counties (details here). NYSDOT will accept comments on the scoping update packet by mail until March 31.