Marco Chitti

@chittimarco

Researcher on urban planning and public transportation.

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Marco Chitti@chittimarco· 28d

"Highly unusual" days are getting closer and closer!

Marco Chitti@chittimarco· 28d

The tram has its own transit signal to manage the crossing of the opposite direction traffic flow

Marco Chitti@chittimarco· 28d

I should write a long-form post starting from this recent picture of a finished section of Bologna's tram, published by the mayor, to discuss how Italy's project delivery framework is good at keeping costs under control, but terrible at delivering quality design for non-engineering aspects.

Marco Chitti@chittimarco· 28d

Bordeaux's tram line A, built in the early 2000s, relies on a priority strategy of right-in/right-out setups for lateral streets coupled with a number of "compact U-turns" to reduce the number of intersections on center-running alignments

Marco Chitti@chittimarco· Jul 13

Achievement unlocked: going out for a late afternoon bike ride on the West Island, deciding impromptu to stay over for dinner in Sainte-Anne-de-Bellevue because there is a nice bike path to the REM, which runs every 15 minutes past midnight to go back home.

Marco Chitti@chittimarco· Jul 10

They need to fix the single-track section below CFF station for that to happen.

Marco Chitti@chittimarco· Jul 8

It's interesting how cities develop a preference for certain traffic management solutions. Besançon has been rolling out these tiny queue-jump + nearside stop setups since the early 1990s. They are not necessarily the most effective, but they rely on simple TSP spire detection tech.

Marco Chitti@chittimarco· Jul 8

Retractable bollards and trams. It doesn't get more French than that.

Marco Chitti@chittimarco· Jul 8

Your daily transit modal filter (and contraflow tram lane). Besançon. maps.app.goo.gl/m6qxsHQj64Dh...

Marco Chitti@chittimarco· Jul 7

Yesterday afternoon I tried for the first time the western branch of the REM, for a REM+ bike beach trip, and it's honestly a tremendous improvement in accessibility to the western island's outdoor amenities.

Marco Chitti@chittimarco· Jul 6

It's unfortunate it stops in 2022, because since 2025 its use is probably off the chart.

Marco Chitti@chittimarco· Jul 6

Happy "highly unusual" day to those who celebrate!

Marco Chitti@chittimarco· Jul 4

Four. But very small. And the bridges are very minimalists. They would not be considered appropriate by most north American design guidelines.

Marco Chitti@chittimarco· Jul 4

Fun fact: the original design of that station had 4 escalators, one at each end of the tiny bridges, making it even more spider-like. Two were shelved as a cost saving measure and only the fixed stairs were kept

Marco Chitti@chittimarco· Jul 4

Or also because a Svizzera, for me a northern Italian, is also this:

Marco Chitti@chittimarco· Jul 3

Now they are spending €140 million to upgrade the terminus with two platforms, a reversing tail, improved circulation etc. That would have cost less to build from day one. BUT On day one the project was on a tight budget and politically on shifting grounds, so this saving was necessary.

Marco Chitti@chittimarco· Jul 3

Also, why on earth is this designed like a full intersection? There is no road on either side!! This could have been a simple multi-stage pedestrian crossing timed to minimize delays for both pedestrians and buses? How can a 700m, 10-year project be designed so poorly?

Marco Chitti@chittimarco· Jul 3

One might say that they did it because they didn't have enough room to accommodate a bus lane (maybe two, one for straight and one for right turns) plus the general traffic lanes but... ... there is a ton of room they acquired to route the temporary deviation when the interchange was demolished!

Marco Chitti@chittimarco· Jul 3

Sometimes I really struggle to understand how Montréal can fail at basic transit priority, even in a multi-million-dollar project like the SRB Pie-IX. At the very end, where Pie-IX crosses Henri-Bourassa and the 439 bus splits, the dedicated bus lane disappears where its needed most to avoid delays

Marco Chitti@chittimarco· Jul 2

"The baby in the Buick" effect is funny. It reminds me of the concept of "critical velocity" in the NFPA 130 tunnel fire safety, that overly focuses on a specific scenario (a large fire) and somehow omits to say that push/pull smoke extraction might de facto condemns everyone downstream to death.

REGULATORS AND THE BABY-IN-THE-BUICK EFFECT
There has been a considerable improvement in recent years in the response of many
regulatory authorities to fire safety proposals based on engineering analysis rather
than on regulatory compliance. Indeed, in some industries such as oil and chemicals,
such approaches are rapidly becoming the norm. However, there is still an almost
universal failure on the part of the authorities to grasp the significance of what is
being presented to them.
A common misconception is that the role of the fire safety engineer is to predict in
detail what will happen in the event of a fire. This is not the case. The fire safety
engineer must produce a design which achieves adequate safety levels. In
demonstrating this, the engineer may make use of some predictive techniques. But,
perhaps surprisingly, these do not need to be precise or comprehensive in every
instance. A small departure from a coded requirement does not place upon the
engineer the task of carrying out a full fire safety analysis. We find that the regulators
behave as though it does.

One reason for this is that regulatory authorities are comfortable with their magic
numbers. If the distance to a door is no more than 45m, the building is safe. They
need to think no further. But what if the distance happens to be 50m? Clearly a moderate improvement in some other fire safety feature of the building should quite
easily compensate for the additional time required for people to travel the extra few
metres. However, under such circumstances the fire safety engineer is frequently
required to provide design fire specifications, smoke filling calculations, evacuation
analysis and so forth even though a building designed to the magic numbers could not
bear such rigorous analysis. The regulating authority may further assume the right to
choose the fire scenario which is the basis for the design, regardless of how unlikely
this might be. There can be endless "what if' questions and the fire safety issues can
entirely dominate in what becomes an unbounded problem.
A simple, if absurd, example is as follows:
The standard fire resistance test gives a reasonable representation of the heat transfer
inside a compartment containing a post-flashover fully developed fire, and we know
that after flashover people inside the compartment will not survive. When it was
demonstrated in a particular instance that the fire loading in car parks was low and
that it was unlikely that fire in one car would spread to another, regulators opposed
any reduction in fire resistance on the grounds that "people leave their babies in the car while they go shopping." Quite apart from the fact that there was no evidence
that people left their babies in this way, the argument was obviously absurd.
Nevertheless, the regulators considered that, in some magic way, the existing rules
would protect the baby.
Current moves towards risk analysis in fire safety engineering may ultimately relieve us of this kind of arbitrary approach. In the meantime we are left to struggle in a system which tends to…

Marco Chitti@chittimarco· Jul 2

Thanks to @stephenjacobsmith.com for suggesting this paper: "Magic Numbers and Golden Rules" Some pretty clever reasoning about "magic" numbers and thresholds in fire regulations, something than can be said for a lot of arbitrary regulations in general. publications.iafss.org/publications...

Magic Numbers and Golden Rules
MARGARET LAW AND PAULA BEEVER
Arup Fire
Ove Arup and Partners
13 Fitzroy Street
London W1 P 6BQ
ABSTRACT
The application of fire safety research using engineering methods is frustrated by
conventional attitudes. The desire of researchers to always achieve a greater level of
understanding means that they cannot recognise that satisfactory engineering solutions
may be achieved with partial information. The desire of regulators to have simple
rules and tests for administrative convenience contrasts with the need of designers to
have maximum flexibility in order to arrive at optimum solutions. The magic numbers
embodied in regulations are accepted without question whilst any engineering solution
is subject to a disproportionately high standard of proof. To move forward, rules
need to have an engineering basis and to be goal related: the purpose of the rules
needs to be understood by both researchers and regulators.

Marco Chitti@chittimarco· Jul 1

Unfortunately, the old alignment that served the towns of Castelnuovo and Acerra much better has been decommissioned at the same time, because in Southern Italy local notables hate grade crossings and don't care about service, just about the idea of job-creating projects.

Marco Chitti@chittimarco· Jul 1

Today the 16.5 km Afragola-Cancello rerouting of the Napoli-Cancello line was opened to revenue service, with new direct trains connecting Naples to Bari in 3:30 and Lecce in 5 h. It's part of the ~€6 bn Napoli-Bari HS-ish line.

Marco Chitti@chittimarco· Jul 1

Similar mood here

Marco Chitti@chittimarco· Jul 1

Better, right?

Marco Chitti@chittimarco· Jul 1

Mmmm ...not sure 4 complete 30cm traffic light sets is enough for visibility and compliance. I think we need at least a couple more. Maybe double each of them and call it a day. And add a "ceci est un ostie de feu tricolore" giant sign beside each one for extra clarity.

Marco Chitti@chittimarco· Jul 1

Il faudrait se contenter d'arrêts non surdimensionnés et accepter d'avoir des phases piétonnes en plusieurs temps, avec des îlots refuges.

Marco Chitti@chittimarco· Jul 1

Corso Traiano à Turin pourrait être une inspiration pour le traitement "SRB" de Henri-Bourassa: utiliser le parterre central pour localiser la voie de bus en amont de l'intersection, tout en gardant une voie pour le virage à gauche aux intersections principales

Marco Chitti@chittimarco· Jun 30

bikes seem to be expected to use the sidewalk

Marco Chitti@chittimarco· Jun 30

Interesting modal filter-based priority setup in Salzburg, enforced the hard way with a barrier. Bus line 21 runs through Weitmoserstrasse to get a more direct route through the neighbourhood, avoiding a left turn at a major intersection, where general through traffic is routed instead.