Typical 14th Street Bridge traffic is almost certainly an overestimate for the increase in use of the GWMP crosswalk. Some 14th St Bridge traffic comes from the north, no? These folks are likely to decrease their current crosswalk usage during the construction, partially offsetting the increase in use by people coming from the south. For instance, anyone who currently commutes from the 110 Trail to the 14th St Bridge (e.g. Courthouse to Navy Yard) uses that crosswalk now but will stop doing so during construction.

That said, there will certainly be a lot of new people starting to cross there. I support and applaud your initiative to use the construction as a justification to focus more attention on the problems with this dangerous crosswalk.