I think it's 35, with the average speed around 40. (when not sitting at lights/in traffic) The thing is, the lanes for this road are barely large enough for the cars, and there is not an inch of shoulder on the side of the street. So whenever I see a biker, he's in the lane itself of the busy thoroughfare when there is adequate space to ride right next to the road.
Memorial's got bits and pieces of bicycle accessibility, it's just not knit together in any coherent way.
-- Eliot Bridge at the west end has a nice underpass grade separating the interchange, but on one side is the travesty that is the Greenough Blvd. sidewalk and on the other side is a too-narrow Memorial sidewalk on the overgrown riverbank. DCR won't do basic vegetation and soil control here making the shoreline appropriate for widening that sidewalk or putting in an adjacent cycle track, but the space is most definitely there and can be done fully environmentally kosher with the riverbank.
-- Riverfront Park out near Harvard has a grade separated side cycle track striped with lanes. But it turns back into a regular sidewalk after a short distance and puts the walkers back in direct competition with high-speed bike traffic.
-- Striped cycle track returns near Western Ave./River St. But it all needs to be widened because the joggers have worn the grass strip between the cycle track and the curb completely bare. Not a lot of great options here, but they can do a less afterthought of a job than this and at least confine the pinch points of mixed ped traffic to smaller areas. Also...after this many years there STILL isn't a ped cycle or so much as a ped button at the Western and River bridges.
-- Magazine Beach near BU Bridge is getting some long overdue work from DCR that'll similarly improve bike access (and rebuilt BU Bridge is striped for bikes now, as are Brookline St. out to Central Sq. and Waverly St. out to MIT). But that's likewise just a disconnected chunk of accessibility.
-- BU Boathouse to Mass Ave. has the hillside worn completely raw by joggers going off the narrow sidewalk, and DCR has been completely negligent at mitigating the soil erosion. That sidewalk is completely widen-able and an adjacent cycle track can go in if they would only stabilize the damn hillside that's filling up the river with eroded silt.
-- Mass Ave. to MIT Boathouse looks like this:
http://goo.gl/maps/7FelH. Another place where joggers and bikers have worn the grass completely bare. Hello!...the people have spoken; that's a cycle track. Let the walkers and tourists hang along the railing and benches and the high-speed ped traffic on a separate track between the sidewalk and road.
-- No easy answers for MIT Boathouse under the Longfellow to the cycle track on Cambridge Pkwy. that takes you the rest of the distance to Cambridgeside. Probably can only stripe a bike symbol in the right lane and put warning signage. But that's not a particularly long stretch.
-- Cambridge Pkwy. has the nice cycle track, low volumes, and underpass of Land Blvd. to Cambridgeside. If they can complete the Somerville Community Path to Lechmere and Northpoint, it's one easy street crossing at Lechmere Sq. to get between the Charles path network and the Somerville path network. This area's in great shape.
You get the picture. It's really not hard to get near-complete bike grade separation on the entire Cambridge/Watertown side of the Charles from Waltham all the way to Museum of Science if DCR would just engage brain and stick to a corridor plan. The fact that so much of this area has had makeshift high-speed paths worn into the grass shows how duh-obvious this is if they'd just tie the segments together. You'd have an unavoidable pinch near River/Western where there just isn't much space to expand, and some crummy but mercifully short-distance mixed traffic under the Longfellow (but better bike lanes coming ON the Longfellow). But that's it for compromised points. The rest of it can be A/A+ bike, ped, and road grade separation end-to-end for not a whole lot of money. And arguably way better for the environment than just letting those worn paths and worn-to-bone shores leak more runoff into the Charles.
