Bristol to Bath Railway Path temporary closure

I'm confused as to whether people are talking about the Staple Hill tunnel on the Bristol to bath railway path or the "two tunnels" on the bike path between Bath and Midford which are the Devonshire tunnel and Combe down tunnel. I have only used the latter when running the "two tunnels" 10k 4 years ago and found the lighting quite tranquil and adaquate. It's the staple hill tunnel I find gloomy and whilst I never use it at night can picture there being behavioral problems at night.
 

fatblokish

Veteran
Location
In bath
The subject is most definitely the "Two Tunnels", as you say, Devonshire and Combe Down tunnels. The steering group briefly considered making a recommendation in the Code of Conduct that lights should be used by cyclists, however this was quickly discounted as it would make the tunnel much less safe for all the other unlit users such as peds, mobility scooters, trikes, scooters, dogs etc who are following in the wake of brightly lit cyclists. Further, the light provided by the 200 or so light fittings in the crown of the Combe Down tunnel significantly exceed the standard of 5 lux.

As you say, the current Two Tunnels lighting is quite adequate.
 

lazybloke

Let's go sledding
Location
In a cemetery
@lazybloke, - not so much anger as puzzlement . . . And I am beginning to wonder if my low-light vision is significantly better than some people’s.

A day or so ago I was travelling south through the Combe Down tunnel. There is a gentle curve at either end, connected by a long straight, the best part of a mile long I guess. As I came onto the main drag, I could clearly see a jogger at the extreme far end. As I say, the best part of a mile away. Now admittedly they were wearing a light top, but this brings me onto my next point of puzzlement.

You say runners are visible, but people behind them may not be. Well, that is true outside of tunnels too, but sticking to the subterranean, I can see that a clearly visible individual or group might distract your attention from a darker person or group in relative shadow behind them. But here is my difficulty: - I have myself experienced that very situation many times, but I am able to see the oncoming group sufficiently far ahead that there is plenty of time to scan the shadows behind them for less well lit traffic. Unless of course, the lead group is using a Very Bright Light, in which case all bets are off

As for recumbents being uniquely at risk from dazzle, remember that relatively few people use proper ‘shaped beam’ lights. Most emit light in a circular beam, so that the risk of dazzle is similar from any angle unless the light is pointed sharply downwards. I have found dazzle to be just as much a problem on upright bikes and no worse on recumbents.

From comments on here, I am coming to the not unreasonable conclusion that some people see better in the dark than others and I happen to be lucky. I am less convinced however, of the value of sticking lights on everything, as this is not only distracting, but can actually make it harder to see ‘between and around’ said lights. (I think this applies to some extent on the roads too, but that’s another debate!).

There is also however, another possibility: I can see to the end of the mile straight. Let’s assume a person with poorer vision can see half that distance, or let’s even go further and assume a person who can only resolve objects a quarter of that distance away. That’s still roughly a quarter of a mile. If that doesn’t givesufficient time to anticipate, then perhaps, just perhaps, somebody is going a teeny bit fast for the conditions?
A teeny bit fast? Nope, anything but ; see my speed in the Strava clipping below.


No, the main reason i couldn't see some other users of the tunnel is because it was so busy with walkers, joggers, doggers and cyclists. I only traveled from Midford/Monkton Coombe to Bath and back, just 5.5 miles total, but have 12 people on my Strava flyby. It's impossible to extrapolate, but I estimate I passed 200-300 other people. Is it any wonder that occasional ninja cyclists are not conspicuous.?



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Dazzling lights shouldn't be relevant to the question of when sensible lights must be used. A "twilighty" tunnel is probably the perfect example of where lights would be appropriate. Anyone know what the law says on the matter?
 

mjr

Comfy armchair to one person & a plank to the next
Anyone know what the law says on the matter?
It says head/tail lights must be used "between sunset and sunrise" and "in seriously reduced visibility" ( http://www.legislation.gov.uk/uksi/1989/1796/regulation/24/made )

I'm not sure where the visibility term is defined. It may be in case law, or it may even still be waiting for a court to rule. http://highwaycode.info/rule/226 says it's when you can see less than 100m but cites no additional laws to back that up and it wouldn't be the first unsupported claim in the highway code...
 

mjr

Comfy armchair to one person & a plank to the next
HSE. I'll not further deprive you of the opportunity of doing your own research
Is it still the fallacy of proof by appeal to authority when the authority is from a different field, or merely an attempted proof by handwaving?

and hope you are not one of the shouty ones who seek to exclude others from using the tunnels.
And I hope you're not one of the nobbers riding unlit on the right.
 

lazybloke

Let's go sledding
Location
In a cemetery
@lazybloke Good Lord, that’s crowded! I’ve never seen it that busy since the opening day procession . . . Good job I went the other way that day!
Watch the first minute of this youtube clip of cycling through the two tunnels on opening-day. Count the number of people in the video, note the playback speed... and it works out as about 25 people per minute passing through the tunnel.

My ride was much slower (actually 56 minutes), so I saw more people. That estimate of 200-300 people works out between 3.6 and 5.4 people per minute, which is a small fraction of the opening day traffic. Still think I'm exaggerating?
Far from being too high, my estimate was probably too low.

However, traffic levels to peak in the tunnel closest to Bath (I think it's the Devenshire tunnel). If the tunnel ahead of you is congested then it's not rocket science to understand that your view is reduced. And that's without factoring-in eyesight issues.

Re dazzling bike-lights, everyone agrees these are a curse, but your solution of doing away with them is a nonsense for other people in the tunnel who have less-than-perfect eyesight (hint: that's the majority of people). Hence my suggestion of using appropriate lights when cycling through the tunnel.
You might not need them, but they are not for you.
 

Seevio

Über Member
Location
South Glos
If the tunnel ahead of you is congested then it's not rocket science to understand that your view is reduced.
It's also not rocket surgery that if the tunnel is that congested then you are travelling slower anyway in which case reduced view is cancelled out. Lights are not needed in the tunnels with the current levels of lighting.
 

lazybloke

Let's go sledding
Location
In a cemetery
It's also not rocket surgery that if the tunnel is that congested then you are travelling slower anyway in which case reduced view is cancelled out. Lights are not needed in the tunnels with the current levels of lighting.
Your eyes are clearly better than mine. Congrats.
What do you say to people who have really bad eyes?
 
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