Franklin Street Arterial, the speedy thoroughfare that connects I-295 with the Portland waterfront, celebrates its fortieth anniversary this summer, but the city isn't throwing it a party. Instead city planners are doing what city planners do and holding a public forum to discuss whether the road should be radically altered. Portland has been trying to spruce up its formally blighted Bayside neighborhood for the past few years, and municipal mucky-mucks see the arterial as an impediment. Sure, it allows 27,000 vehicles to whisk easily into the heart of the city. But it also cuts off Kennedy Park and adjoining neighborhoods from the urbane activity around Whole Foods and Planet Dog. Cross at your own risk. If you want to creep out into the controversial lane, you can register for the Franklin Arterial Design Workshop at 7 p.m. Wednesday, April 29, at the Ocean Gateway terminal by visiting www.portlandmaine.gov or calling 207- 874-8801.