Why you shouldn’t pass on a blind curve.

[Steve O]

@ShawnoftheDread 120404 wrote:

I think he’s saying we need to make the trail more narrow so demand decreases and congestion eases.

If you build it narrow enough, demand drops to zero and there is no congestion at all.
[IMG]http://bikearlingtonforum.com/attachment.php?attachmentid=9125&stc=1[/IMG]

[GovernorSilver]

@rcannon100 120408 wrote:

As a networking principle, there is always some point where sufficient capacity will satiate demand.

Next question: What is that point? Which is more affordable? Increasing capacity or decreasing demand? What will happen to demand as you add N+1 capacity?

Where your supply of capacity is virtually infinite and relatively cheap, the answer would be capacity.

Where increasing capacity has high costs, one might think about how to alter demand.

But as for todays proposition….. once congestion has been reached, you can no longer accurately measure demand.

Sounds like not riding the MVT on weekends has little impact on the measurement of demand, since congestion has already been achieved. Unless I read this wrong of course.

I’m glad I have the Potomac Ave. Trail to take as an alternative – to a certain extent anyway. At least I can use it to avoid that cantilever bridge.

[GovernorSilver]

@dasgeh 120411 wrote:

You could also title this thread: why trail designers should not design trails with blind curves.

I wonder if that is even possible – to design a trail as long at MVT without any blind curves at all.

Too bad that convex mirror is a fail.

[dasgeh]

@GovernorSilver 120431 wrote:

I wonder if that is even possible – to design a trail as long at MVT without any blind curves at all.

Too bad that convex mirror is a fail.

I-95 is a lot longer and there are no blind curves

[GovernorSilver]

@dasgeh 120437 wrote:

I-95 is a lot longer and there are no blind curves

It’s also a lot wider. I’m guessing whoever built it had the funds to just blast through hills/mountains to eliminate any potential blind curves – far more than whoever built MVT. I wouldn’t mind being corrected on this point though, as I have no background in civil engineering or anything like that.

Potomac Ave. Trail has no blind curves but I guess this is possible because it is entirely on flat terrain.

[mstone]

@Steve O 120418 wrote:

If you build it narrow enough, demand drops to zero and there is no congestion at all.
[IMG]http://bikearlingtonforum.com/attachment.php?attachmentid=9125&stc=1[/IMG]

I don’t think it’s demand that’s dropping

[mstone]

@GovernorSilver 120439 wrote:

It’s also a lot wider. I’m guessing whoever built it had the funds to just blast through hills/mountains to eliminate any potential blind curves – far more than whoever built MVT. I wouldn’t mind being corrected on this point though, as I have no background in civil engineering or anything like that.

Trail designers have traditionally made winding trails like MVT for aesthetic rather than technical reasons; it’s not all that hard to straighten up something that trivial. It’s certainly more pleasant to amble along on a winding path than, say, the fairfax county parkway trail. When people then mix peds & bikes, OTOH, the results are a bit of a fail.

[peterw_diy]

Hold on to that video. Alexandria is beginning to discuss the future of that site. The recent Waterfront plan suggests the City will want a continuous MVT and will consider giving the GenOn property owner perks in exchange for improving the trail there, especially if there’s documentation of risk.

I guess this should go in the Alexandria BPAC section, but the city is looking for advisory committee members. It would be great to have some MVT commuters… https://www.alexandriava.gov/planning/info/default.aspx?id=86036

[GovernorSilver]

@mstone 120447 wrote:

Trail designers have traditionally made winding trails like MVT for aesthetic rather than technical reasons; it’s not all that hard to straighten up something that trivial. It’s certainly more pleasant to amble along on a winding path than, say, the fairfax county parkway trail. When people then mix peds & bikes, OTOH, the results are a bit of a fail.

I would have thought it’d just be cheaper to build a paved trail that conforms to landscape that is not perfectly flat, because making it straight would require spending money on bridges and blasting away/digging out earth that just happens to be in the way.

But like I said I don’t have a background in civil engineering. Maybe it would truly be cheaper to make the MVT straight if it didn’t exist right now and was being built from scratch. The Potomac Ave Trail is newer and mostly straight as an arrow, but then again it was built on already flat terrain rather than a bumpier landscape like where the MVT is now.

[Vicegrip]

Better trail use and rules education for users can increase capacity too. Many times what I see is not an overall overcapacity but a bottleneck due to user error.

[dbb]

@Vicegrip 120457 wrote:

Better trail use and rules education for users can increase capacity too. Many times what I see is not an overall overcapacity but a bottleneck due to user error.

If we could get those peds into a paceline, the trail capacity would increase dramatically! All that space between them is wasted.

[CaseyKane50]

@dasgeh 120411 wrote:

You could also title this thread: why trail designers should not design trails with blind curves.

From a history of the Mount Vernon Bike Trail.

Most of the trail, laid out before national bicycle trail standards were available, was designed to minimize the removal of trees.

I am quite sure that the trail would look much different today, if it had been designed at a later time.

Interestingly, the section where the accident occurred was not built until 1982-83 following a settlement with the owner of the coal-fired generation plant. From “Paved Recreation Trails of the National Capitol Region”

The most imaginative project occurred in 1982-3 to place the Mount Vernon Trail between an electrical generating plant and the Potomac River north of Alexandria. In the face of legal action after many years of storing coal on federal land, the utility company set up a compensation fund which paid for this work.

Also of note,

Until 1970, cyclists travelled on the Parkway itself; on Sundays the northbound lanes were closed for use as a recreational route. The first section of new trail to be laid out continued south from the 14th Street bridges to Alexandria, weaving alongside National Airport.

[PotomacCyclist]

I’ve seen people pass at several of the blind curves along the MVT, not just at that bridge. I’m always amazed when people do this, especially when they are traveling at high speed. They are putting their own safety (as well as the safety of others) at risk by chancing a head-on collision that they wouldn’t be able to avoid. You would think that even if they are that self-centered, they would still care about their own well-being.

Other hot spots for this behavior include the turn just south of the Gravelly Point parking lot and the turns just north of the Daingerfield Island marina. I’ve even seen the aftermath of single-bike crashes at these turns. Maybe the riders head into the turns with too much speed, then hit a tree or fly off the trail.

I agree with everyone else that the MVT can be wild and crazy on weekends. The weekday peak rush hours can be hectic too.

[AFHokie]

@PotomacCyclist 120501 wrote:

I’ve seen people pass at several of the blind curves along the MVT, not just at that bridge. I’m always amazed when people do this, especially when they are traveling at high speed. They are putting their own safety (as well as the safety of others) at risk by chancing a head-on collision that they wouldn’t be able to avoid. You would think that even if they are that self-centered, they would still care about their own well-being.

Other hot spots for this behavior include the turn just south of the Gravelly Point parking lot and the turns just north of the Daingerfield Island marina. I’ve even seen the aftermath of single-bike crashes at these turns. Maybe the riders head into the turns with too much speed, then hit a tree or fly off the trail.

I agree with everyone else that the MVT can be wild and crazy on weekends. The weekday peak rush hours can be hectic too.

Some of those curves wouldn’t be quite so blind if the greenery was trimmed back a bit

[consularrider]

@AFHokie 120513 wrote:

Some of those curves wouldn’t be quite so blind if the greenery was trimmed back a bit

But, but . . . it’s a park, isn’t it? Green equals nature. Those darn pesky cyclists. :rolleyes:

[Author]

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