More about tunnel “replacement” scenarios

The Garden City Conservation Society board of directors strongly agrees with Scenarios 1 and 4 (with qualifications) in the George Massey Tunnel Replacement Project “Exploring the Options scenarios. Both of those options maintain the existing tunnel. There are only advantages to that. There are no major disadvantages on the basis of what the public can learn so far.

There’s an online feedback form for this until at least the end of April 2, 2013.

This excerpt from the Phase 2 Guide lists the five scenarios:

Massey Tunnel scenarios

Scenarios 1 and 4 both maintain the existing tunnel. There are only advantages and no real disadvantages.

The only known reason for replacing the existing tunnel is to deepen the channel to allow larger ships up the Fraser River. However, that is supposedly not a goal of the project, and the conservation effects of it are not good ones. Here are some quick comments prompted by supposed reasons that don’t stand up to examination:

  • The earthquake preparedness of the existing tunnel can be upgraded to the point that it would out-survive most of the buildings and infrastructure on either side of the river. (At least that’s my conclusion after consulting a reliable engineer.)
  • Along with the earthquake upgrading, the tunnel will need internal upgrades for ventilation, lighting, etc., apparently in ten or fifteen years. However, since the tunnel “tube” is made of concrete, which gets stronger with time, the tube (essentially the tunnel) is getting better, not worse. All the refurbishing that is needed would be easier to accomplish, and less expensive, than building a new structure.
  • On balance the tunnel is relatively safe, even though it should never have been built without an emergency-access route (essentially a sidewalk in each tube). If the tunnel is completely replaced, it will most likely be by a bridge, which is less safe in icy and foggy conditions. Since the project engineer envisions steep approaches, that will be especially problematic with snow and ice.

One of the greatest needs is for the new Steveston Highway Interchange, as proposed 22 years ago. That would stop backups in the tunnel, especially northbound ones, since Steveston Highway Interchange backups in rush hour can block the only northbound lane, bringing all traffic toward Richmond and Vancouver to a halt. That plus the effect of about 10-20% of the tunnel traffic diverting via the new perimeter road (in Delta) will greatly reduce congestion, and it could be all that is needed.

However, we do want to strongly encourage transit, including every possible way to enable reliable rapid crossing of the Fraser River on the Highway 99 route. To enable that, we see an additional two-lane crossing on that route.

Personally, I see a new two-lane tube. It would include sidewalk, with a firewall between sidewalk and traffic, with firedoors, probably with sealed fireproof windows. It would be up to a hundred metres east of the existing tube, still within the corridor, which is quite wide where it meets the river.

As a board of directors, we have not ruled out a bridge with the same capacity for the transit purpose. However, it is making less and less sense as more factors come to light:

  • It seems counter-intuitive to have rising approaches ascending toward a 211-foot-high bridge crown next to flat-to-declining approaches.
  • It also seems shortsighted to build one structure above the other when they have different life expectancies. The new bridge over the old tunnel might have to be removed first, since tunnels have much longer lifespans, but the removal would be awkward either way.
  • The lifespan aspect also has a huge cost effect, making a bridge vastly more expensive on an annual basis than a tunnel of the same price because the tunnel construction cost can be spread over so many more years.
  • From the standpoints of noise and aesthetics, the tunnel method is better in this location, and there is no reason to give up those advantages either.
  • Also, the tunnel construction takes a much shorter time, and the environmental assessment would likely be simpler.

The existing tube is rectangular, but the new one could be circular (but with a rectangular traffic route), and one of the advantages is that the sections can be built in a shipbuilding dry dock before being floated to the trench and immersed. That would limit the impact on the Delta/Richmond shores. It also happens to be less expensive because, as the preliminary report on options way back in 1955 stated, “The external loads on the tunnel can be carried more efficiently by the circular shape.” (It’s over 57 years later now, but the basic physics principles wouldn’t change.)

Since our focus is on an optimal choice for transit, the new tube should be suitable for either light rail or buses. (If it is ever used for light rail, the eventuality would probably happen later.) For buses, the two lanes for that purpose would not necessarily be the new ones, although a reason in favour of that is that the wider lanes would be good for buses, wide vehicles that need to travel fast safely.

Since buses don’t necessarily require sole use of a lane in each direction, two suggestions I’ve heard are (a) to make the bus lanes also HOV lanes or alternatively (b) allow toll-paying trucks in the bus lanes. In both cases, that would need to be monitored so that the HOV or truck use does not in any way impede the bus flow. It also should not limit the possibility of eventual light rail use.

We continue to believe that the new tube should initially be used to replace one two-lane side of the existing tunnel at a time while all forms of upgrading are done on that side. That way the existing tunnel will be better than new for health and safety, and the whole six-lane tunnel, all either new or better than new, could celebrate its opening after that. If the planning is committed to the sorts of values being advocated, this grand opening would be a celebration of a leading-edge set of priorities in keeping with the values of Delta and, increasingly, Richmond.

Later, when the new tube is available for transit purposes, it might well be that transit would actually use one lane on each side of the Highway 99 corridor.

Since we also strongly support safety (conservation of human life and wellbeing), the ideal approach would be to always have four lanes in one direction and two lanes in the other direction, with the centre lanes behaving like the counterflow lanes in the current operation. This would eliminate the fear (and occasional reality) of head-on collisions in a tube with lanes flowing in opposite directions.

A final detail: All of this should be done in a way that allows for the possibility of another two-lane tube being added on the west side of the Highway 99 corridor at some future time, although we basically hope it won’t happen. Of course, the intent if it does happen could be to enable a dedicated emergency lane and a lane dedicated to pedestrian and bicycle/rolling use, and maybe the future will evolve to the point where a scenario like that would be considered.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s