Last Thursday afternoon at the Castleknock M50 flyover, vehicles sped down the motorway on either side.
In the space of 20 seconds, there were 19 jeeps with one occupant headed towards the city centre and 15 saloons also with just the driver.
The three lanes of the M50 are at the moment divided up into one for normal driving, one for overtaking, and a third for when there are queues in the first two or a need to overtake again or make room.
Could one of them, instead, be reserved for vehicles carrying multiple people, leaving all those single-occupancy jeeps and saloons to share the remaining lanes?
Some other cities have dealt with congestion on their fringes by opening up high-occupancy vehicle (HOV) lanes, giving those who carpool the perk of a clearer route into the centre.
And in 2008 then-Minister for Transport Noel Dempsey of Fianna Fáil briefly flirted with the idea of introducing HOV lanes here.
At the time, Dempsey said the best way to reduce congestion and ease carbon emissions was to reduce car use, but that he was considering introducing HOV lanes too, according to the Irish Independent.
It never happened. Meanwhile, traffic on the M50 has been increasing, rising by 4.4 percent between 2015 and 2016.
The US has built more than 2,500 “lane miles” of HOV lanes, according to a 2012 survey of the literature on HOV lanes by Sharon Shewmake, a researcher there.
Do they work? The evidence is mixed – and inconclusive, Shewmake found.
Proponents say HOV lanes get more people where they’re going faster, and that such lanes can relieve congestion in regular lanes by encouraging people to carpool, thus moving the same number of people in fewer cars, according to Shewmake’s paper.
But detractors say such measures may simply encourage more people to drive, because they find it faster and easier. This could tempt “drivers who were previously taking other routes, not driving, driving off-peak, or taking transit, a behavioral response known as induced demand”, Shewmake says. That has implications for energy use and environmental impacts.
Furthermore, even if the goal of HOV lanes is simply to make the commute faster, regardless of impacts on sprawl, energy use and the environment, then they can fail there too. As they tempt more and more people to carpool, they can fill up and become no faster than general-use lanes, Shewmake’s paper says.
And a 2005 study by the Australian Institute of Traffic Planning and Management, which examined HOV lanes in Brisbane, found among other things that, in order for HOV lanes to work, enforcement was also important.
Perhaps for these reasons, the National Transport Authority is not looking at the idea of HOV lanes. Said a spokesperson: “There’s no plan to revisit that.”
Dublin City Councillor Ciarán Cuffe of the Green Party, who is chair of the council’s transport committee, said that he remembers the HOV-lane debate in Ireland in the mid-1980s.
But having travelled on these lanes in Florida, in the US, he is not convinced. “They may be appropriate for some of the motorways on the periphery of Dublin city,” he said, but not closer to the city centre.
“We tend to use that extra lane for a bus lane and it wouldn’t be appropriate to jam up the bus lanes with cars, even if they’ve three people in them,” he said.
There have been requests over the years to use bus lanes for other vehicles, said a spokesperson for the Department of Transport, Tourism and Sport.
Requests have come in from those who drive hackneys, limousines, animal ambulances, motorcycles, electric vehicles, and multi-occupancy vehicles, they said.
But there are only a few exceptions to the buses-only rules for some lanes.
Emergency services can use bus lanes for obvious reasons, and cyclists are allowed as they are vulnerable and safer in bus lanes, the spokesperson said. Taxis are allowed in some cases, because they are available to the public for on-street hire, they said.
But any expansion of their use to, say multiple occupancy, has been rejected by successive ministers, including the present minister, Shane Ross, “because they would undermine the efficiency of the lanes for the purpose for which they were originally created”, said the spokesperson.
“Their purpose is to encourage greater use of buses by making bus services faster and more reliable, thereby attracting more people to switch from private cars to buses, and so reducing congestion and pollution,” they said.
Sharing a Car
As Councillor Cuffe sees it, the answer to congestion in the city lies in more public transport and more cycling – and fewer cars.
The National Transport Authority’s (NTA’s) transport strategy is focused on more public transport and cycling and walking in urban areas, said thee NTA spokesperson.
These “will provide the means to cater for much of the increased travel demand,” the spokesperson said. But the agency is also looking at what are known as “complementary demand management measures”.
Among them: ways to implement and expand car-club schemes, car pooling and car sharing in Dublin city.
It is early days, but it’s something Cuffe says needs to happen, and Dublin City Council has lately “been bending over backwards” to facilitate such schemes.
“The likes of both GoCar and YUKO are really, really positive for the city and we need more of them,” said Cuffe.