What has changed in the traffic patterns in Boston since all the Big Dig roadways have all been opened?

A lot.

The following is a completely unscientific traffic reporter's assessment of the alterations in the traffic pattern around Boston resulting from the Big Dig.

Better:

Xway NB – Particularly in the afternoon the Expressway moves much better than it had before the opening of the O’Neill Tunnel. Some time ago, it was generally expected that there’d be a delay from at least Mass Ave. up to the old South Station Tunnel. That delay is now significantly diminished. It should be noted that during the morning the pattern is still much the same as before the opening.

Pike EB and WB – Metro West travelers have probably experienced the greatest benefit related to the Big Dig.  Getting to and from Logan Airport is significantly faster these days. Yes there are still delays on the EB Pike approaching the Xway and South Station ramps. But travelers heading to Logan no longer have to make that excruciating trip up the NB Artery to the Callahan.

Storrow / Memorial Drives EB – There are still delays on Storrow Drive approaching Leverett Circle, but they are generally shorter and less frequent than they were before the new lane configuration at Leverett Circle. Delays on Storrow Drive can still be expected when there’s an event at the Garden, or an incident affecting the Leverett Connector, or the O’Neill Tunnel, or even if it’s a heavy volume day.   Memorial Drive EB backs up much less than it used to as well.

Tobin Bridge – Prior to the completion of the new road, the Tobin Bridge commonly backed up to the tolls and beyond during the morning rush. There are still delays on the loop ramp, but they are less significant than before. Just as before, delays sometimes occur approaching the toll plaza.

Sumner Tunnel – Before the Ted Williams Tunnel opened your only real choice was the Sumner. The Sumner regularly backed up every morning onto the McClellan Highway (Route1A). Nowadays, those backups are rare.

Central Artery / O’Neill Tunnel – Do you remember the old days on the Artery? It used to be a literal parking lot between 3 and 6 pm every afternoon. Do you remember mornings with the cops at Dock Square with the lane restriction that backed up the SB Artery onto the Lower Deck? Sure there are still slowdowns, but it’s nothing compared to the old Central Artery.

Downtown Surface Streets: Traffic flows more smoothly now that there are more efficient access ramps to 93 and the Mass Pike.

Worse:

Xway NB – While traffic is better on the approach to the O’Neill Tunnel, as discussed above, nowadays we regularly see significant delays between Braintree and Neponset Circle during the afternoon rush hour. This was rarely the case before the O’Neill Tunnel opened.

93 North of Boston – In the same way that the NB Xway is backed up in the afternoon, 93 NB now commonly sees delays leaving the city from Somerville up to 128. This is a delay that we did not regularly see before the O’Neill Tunnel opened. In the morning, Route 93 South is routinely backed up beyond Route 128 coming into the city. After the Leverett Connector exit, traffic generally moves better into the O’Neill Tunnel. Before the Big Dig, we reported delays on Route 93 all the way the Central Artery.

Boston Recurring Congestion - Before the Big Dig

Boston Recurring Congestion - Now

Update (3-1-07):

Below is a link to another blog with an additional opinion.

http://www.briankaneonline.com/2007/02/just_dont_get_off_the_highways.html