Preventing overheight trucks from crashing into freeway overpasses.

This was a blog post that was going to start out as criticism, but as time has progressed, the British Columbia Ministry of Transportation has addressed the problem admirably and taken the wind out of those critical sails, so you will get to hear the story of what they did to improve the quality of one of BC's freeway overpasses to prevent accidents and protect infrastructure.

The story



In the 1960s, the overpasses above Highway 1 were built to similar design and varying clearance.  Perhaps in those days it was inconceivable that trucks would stretch 4.4 Meters (almost 15 feet) into the air, or perhaps years of additional paving shaved inches off of that clearance.  Whatever the case, we find clearance signs with various "heights" recorded on most of the overpasses East of Vancouver 4.6 Meters being the most common I've observed.

 

[caption id="attachment_565" align="aligncenter" width="300" caption="Overpass Clearance (one of many)"][/caption]

 

[caption id="attachment_566" align="aligncenter" width="300" caption="Overpass clearance - 2"][/caption]

[caption id="attachment_567" align="aligncenter" width="300" caption="Overpass clearance - 3"][/caption]

Year before last, some surprised trucker plowed into the Glover Road freeway overpass Eastbound on Highway 1 in Langley.  That particular overpass was a little lower than some of the others, so conceivably he might have driven quite some way before having his big rig stopped (the hard way).  The damage to the overpass was significant enough that traffic on Glover Road was reduced to 1 way alternating traffic for the several months it took for repairs.

I'm sure someone in the Ministry of Transportation thought "Wow, that was shocking, that guy's truck just hit the overpass.  Hope that doesn't happen again..."

Last year, another surprised trucker plowed into the same Glover Road overpass.  Same damage, same road closure with alternating traffic.  The repairs made one side of the overpass solid, presumably to lend additional strength to the bridge (under siege).  Since that second repair, there have been additional precautions taken, which together have formed a system to try and prevent this from happening again.







 

[caption id="attachment_569" align="aligncenter" width="420" caption="Overpass under siege (repaired again)"][/caption]

Preventing the collisions

 

First there were 2 signs positioned further up the road on either side which re-stated the clearance information printed on the bridge.  With advance warning a trucker could conceivably stop before hitting the bridge.  The signs used bright contrasting colours to draw attention.

 

[caption id="attachment_570" align="aligncenter" width="420" caption="Bright clearance signs (with enough room to stop)"][/caption]

 

Next, a bunch of yellow and black reflective signs were added to the bridge to draw attention to the bridge.  

So if a trucker was overheight, knew he was overheight, read the signs, did the math and stopped in time he could avoid hitting the bridge.  But what if he didn't know he was overheight? 

A series of bright yellow warning / informational signs were deployed, starting with a sign warning trucks to use the right lane for the overheight detection system. 

 

[caption id="attachment_571" align="aligncenter" width="420" caption="Truckers Keep Right for overheight detection system"][/caption]

Then the overheight detection system which triggers a flashing overhead sign that would warn when a truck was overheight.

 

[caption id="attachment_572" align="aligncenter" width="420" caption="Glover Road Overheight detection system uses beams (of light) when interupted, flashing signals are triggered."][/caption]

[caption id="attachment_573" align="aligncenter" width="420" caption="When flashing give that overheight truck that isn't stopping lots of room"][/caption]

 

Then a small pull-out was built where trucks could pull off the freeway to check their loads.  It had a large bright yellow "pull-out" sign for easy identification, and a series of bright yellow signs warning that the pullout was approaching.  At the pullout there is an informational sign intended for those who have used the pull-out (my eyes are good, but at 100km/h that font is too small even for me :-) ) 

 

[caption id="attachment_574" align="aligncenter" width="300" caption="overheight truck pullout ahead"][/caption]

 

[caption id="attachment_575" align="aligncenter" width="300" caption="overheight truck pullout ahead (getting closer)"][/caption]

 

[caption id="attachment_576" align="aligncenter" width="300" caption="overheight truck pullout NOW! (no seriously, NOW)"][/caption]

 

 

 

So now overheight trucks can be detected and "flashed", and there is an illuminated pullout available for these trucks.  Assuming that works and the driver notices he is overheight, this challenge remains for a driver who is overheight.  He either needs to back up the freeway for 2-3 miles, or he needs a crane to unload him so he can drive underneath the bridge.

Now the Ministry has added a "detour route" informational sign West of the 200th street interchange in the same bright yellow colour, warning drivers of overheight vehicles to detour off of the freeway.

Good job guys, hopefully we don't see another accident at that freeway overpass like the last two.

 













The unmeasured cost

Glover road was reduced to single lane alternating traffic next to a university on the main road leading from Langley to the Albion ferry crossing (on the Fraser river).  Thousands of people had to wait each day while traffic changed direction to cross the freeway.  This took them away from their families, their jobs, their volunteer engagements.  This time was simply lost.  Add to that unmeasured cost, the construction costs and the real cost of not putting signage up after the first incident becomes more apparent.  The albion ferry is reported to have moved about 4,500 people per day, so this number would be reasonable for forming an estimate. Assuming a 1 minute delay for 4500 cars per day for 180 days (2 years 3 months out of service each year), with commuters earning $25/hour, the inconvenience could have cost citizens. $337,500 over 2 years.  That number will never appear in a government balance sheet, but it is a cost that was paid by citizens, and it is a cost we may be able to avoid paying in the future thanks to the improvements brought by the Ministry of Transportation.

 

[caption id="attachment_577" align="aligncenter" width="336" caption="Traffic congestion HWY 1 Eastbound"][/caption]

 

I find it ironic that the train bridge overpass to the East of Glover Road (bearing scars from previous impacts) is even lower...  We'll wait and see if that has been taken into account. 

[caption id="attachment_568" align="aligncenter" width="420" caption="The "even lower" railway overpass to the East (notice the repairs from past collisions...)"][/caption]









Cheers,
Greg