Question about overweight trucks and VMS signs.

[ftran999]

Yesterday riding home northbound on the Expressway just before the T. O.
Tunnel the VMS sign above the road way was flashing a message something to
the effect "Overweight vehicle stop and wait for police" (sorry don't
remember the exact words). So does this mean there somehow is a means of
detecting the weight of passing vehicles which will prompt the VMS to flash
a warning or is this just a general message warning drivers of overweight
trucks that they should pull over and wait for police.

[gskill]

Post by ftran999
Yesterday riding home northbound on the Expressway just before the T. O.
Tunnel the VMS sign above the road way was flashing a message something to
the effect "Overweight vehicle stop and wait for police" (sorry don't
remember the exact words).  So does this mean there somehow is a means of
detecting the weight of passing vehicles which will prompt the VMS to flash
a warning or is this just a general message warning drivers of overweight
trucks that they should pull over and wait for police.

The sign probably said that the vehicle was 'overheight', not
'overweight'. There are sensors, light beams, I believe, that cross
over the highway shortly before the tunnel entrances to catch
overheight vehicles so they don't crash into the tunnel's roof, like a
car carrier truck did a month or so ago. They want the drivers to
wait for the police so that the police can assist in backing the
overheight vehicle out of there like they do on Storrow Drive. I also
think they beams are set an inch or two lower than the actual tunnel
roof height which is why you occaisonally see the sign lit but no
truck stopped nor crashed.

Jerry S

[Roger Lincoln]

How much space is there between the sign and the tunnel entrance?
Should I be on the lookout for a big rig suddenly slamming on its
brakes in the middle of the roadway or is there enough time to for it
to safely decelerate and pull over? (assuming driver's are actually
attentive to the sign)

Post by gskill
The sign probably said that the vehicle was 'overheight', not
'overweight'.  There are sensors, light beams, I believe, that cross
over the highway shortly before the tunnel entrances to catch
overheight vehicles so they don't crash into the tunnel's roof, like a
car carrier truck did a month or so ago.  They want the drivers to
wait for the police so that the police can assist in backing the
overheight vehicle out of there like they do on Storrow Drive.  I also
think they beams are set an inch or two lower than the actual tunnel
roof height which is why you occaisonally see the sign lit but no
truck stopped nor crashed.
Jerry S

[gskill]

Post by Roger Lincoln
How much space is there between the sign and the tunnel entrance?
Should I be on the lookout for a big rig suddenly slamming on its
brakes in the middle of the roadway or is there enough time to for it
to safely decelerate and pull over?  (assuming driver's are actually
attentive to the sign)

Post by gskill
The sign probably said that the vehicle was 'overheight', not
'overweight'.  There are sensors, light beams, I believe, that cross
over the highway shortly before the tunnel entrances to catch
overheight vehicles so they don't crash into the tunnel's roof, like a
car carrier truck did a month or so ago.  They want the drivers to
wait for the police so that the police can assist in backing the
overheight vehicle out of there like they do on Storrow Drive.  I also
think they beams are set an inch or two lower than the actual tunnel
roof height which is why you occaisonally see the sign lit but no
truck stopped nor crashed.
Jerry S- Hide quoted text -

- Show quoted text -

Duuno exactly. I seem to remember that the sensors are on posts
southbound about at the top of the bridge where it starts to go down
to the tunnel. Providing the driver is paying attention and is aware
the sign is referring to his rig, there is enough time for him to
brake and quickly pull to the right without an all out panic stop, but
not much more.

Jerry S