Just when we got a truce in Seattle's war over a waterfront tunnel, another tunnel debate is brewing. Bellevue wants one for light rail planned for its downtown. But dollars are limited and Bellevue's tunnel-wanna may conflict with Redmond's desire to have light rail service extend to its downtown. Given costs, doing both might not be possible. It's a huge issue, but not necessarily a question that will get much discussion as voters in November consider Sound Transit's $10.8 billion plan for rail improvements and other transit services. The budget for the East Link light rail, which is part of a package called Sound Transit 2, assumes elevated rail through Bellevue, not a tunnel, which would cost another $500 million, give or take. No one knows for sure till more engineering is done, as Seattle learned when costs soared for a proposed tunnel to replace the Alaskan Way Viaduct. The Sound Transit plan also assumes that rail service through Bellevue stops at Overlake, near Microsoft. Going another 3.5 miles to downtown Redmond would cost another $800 million. So far, Redmond, Bellevue, and Sound Transit officials are downplaying any talk of a conflict. No one wants to jeopardize the November vote. But tensions exist. Sound Transit has struggled mightily to emerge from controversies over cost overruns and schedule delays with the first phase, Central Link light rail from downtown Seattle to Seattle-Tacoma International Airport, which is to be completed in 2009. For Sound Transit 2, the agency wants to err on the side of underestimating revenue and overestimating costs so things work out at the end. (Critics of the agency at this point would say that Sound Transit said the same thing in 1996, when voters approved the first phase. Big problems emerged later. The agency says it's learned much from past mistakes.) For now, Sound Transit will only commit to studying the possibility of doing a Bellevue tunnel and deciding that issue in 2008. Bellevue says a tunnel is the only thing that should be studied. Though the two cities' desires are not necessarily in conflict, Redmond understands that a decision to build a Bellevue tunnel potentially makes Redmond a loser. "If we do a tunnel in Bellevue, we probably can't get to downtown Redmond," says Redmond planning official Terry Marpert. And yet there's some hope that savings can be found here and there – picking cheaper approaches from the south leading into downtown Bellevue, for example. "There are a lot of tradeoffs that can be made elsewhere," says Bellevue transportation planner Bernard van de Kamp. Another hope is that revenue from tax collections will exceed what Sound Transit expects. Keeping both Redmond and Bellevue happy would cost $1.3 billion, give or take. And that's the problem. "The big issue is money," says van de Kamp. Always.