By Raymond Buchanan
BBC Radio Scotland's Sunday Live
More than half of the Edinburgh residents balloted on proposals to introduce congestion charging in the city have voted in a referendum.
Edinburgh officials want to go down the same road as London
On the day before the polls close, the turnout stood at 51.5%, with 150,000 postal votes having been returned from the 291,000 sent out.
Voting ends at 2100 GMT on Monday evening, with the final result expected to be announced at Tuesday lunchtime.
The turnout is above those achieved in other recent referenda in the UK.
Professor John Curtice, from Strathclyde University, said the figures were respectable.
He told BBC Scotland: "If you look at the referendum vote for an assembly in the north east of England, they only managed a turnout of 48%.
"If Edinburgh look to be approaching 60% when all votes are counted then they're on target to do as well as a general election."
The debate over congestion charging in the capital has been fierce and divisive.
Opponents of the scheme say it is yet another tax on motorists which will damage business in the city.
Supporters point to the potential environmental benefits and say the money earned will go towards better transport infrastructure for Edinburgh.
If residents approve congestion charging it will see the introduction of two zones around the city.
The inner cordon will operate between 0700 and 1830, Monday to Friday, with the outer cordon effective from 0700 to 1000 on weekdays.
The charge will be £2 per day, with special cameras monitoring vehicles entering the city.
Shop owners have criticised the proposals and urged people to vote no.
Peter Winters, who represents the city centre retailers consortium, told BBC Radio Scotland's Sunday Live programme: "Our biggest problem is that we are concerned that public transport improvements are not in place before they introduce congestion charging.
"Normally, before you try and change people's behaviour you give them some kind of incentive.
"Here, we're looking at doing it the reverse way round, the charge will come in and then we'll give you transport improvements."
Retailers are opposed to the idea of having two cordons and point to the detrimental effect they say the charges will have on trade.
Mr Winters added: "We know we will lose money.
"A recent survey found that, Monday to Friday, retailers would lose 7% of their business. We cannot afford to lose that."
But environmental campaigner Andrea Elderfield said the congestion charges will be good for the city.
She said: "It will make Edinburgh a cleaner, safer city where people can move around and go shopping by tram and bus.
"I walk my nephew around this city and I don't like it that fumes are constantly in his face.
"It's a legacy that we are leaving our children. If we're not thinking about the future, we're being selfish."
Ms Elderfield also believes that the charge of £2 per day is affordable for most motorists.
She said: "£2 a day is not very much for me and I don't think it is for anyone who owns a car.
"The cost to the environment is actually £15 a day if you were going to pay the true cost of what you're doing in polluting."
Drivers would have to pay £2 to pass each cordon
In West Lothian, the council is conducting its own referendum. So far, 44% of the 100,000 ballot papers posted to residents have been returned.
All political parties in the council area are opposed to Edinburgh's plans.
Councillor Willie Dunn said: "People think it's a bit of a cheek to pay to go into Edinburgh when they can come here for free.
"We've said from the word go that this scheme is unworkable and we've said from the word go that this scheme is unfair and unjust and all along the way we've been proved right."
However, Councillor Dunn is not confident that leaders in Edinburgh will pay much attention to West Lothian's referendum.
"To be fair to them they've never taken much notice of all the warnings we've given them up until this point."
And he added: "Our idea of having a ballot was to make sure our voices were heard when the Scottish Executive were taking everything into account."
If Edinburgh votes against congestion charges it will be a blow to environmental campaigners across the UK.
Bristol, Cardiff and Manchester are all monitoring Edinburgh's progress.
However, Professor David Begg, the chairman of the government's commission for integrated transport, said congestion charging is the only way forward.
He told Sunday Live: "We face a stark choice in all our cities. We either introduce congestion charging and cut congestion levels or we allow congestion levels to rise and rise.
"There's not a public transport solution to congestion.
"Everyone wants better public transport but on its own its not going to cut congestion levels."
INNER CORDON ENTRY POINTS
1a. Glenogle Road
2. Brandon Terrace
4. Eyre Place
5. Cornwallis Place
6. Mansfield Place
7. East London Street
8. Leith Walk
10a. Regent Terrace
11. Regent Road
12. Calton Road
14. Holyrood Road
15. St Leonard's Street
16. Clerk Street
17. Hope Park Crescent
18. Melville Drive
21. Home Street
22. Dundee Street
23a. West Approach Road (Dundee Street access)
23b. West Approach Road (Westfield Road access)
24. Dalry Road
25. Roseburn Terrace
26. Belford Road
28a. Randolph Cliff
30. Deanhaugh Street
OUTER CORDON ENTRY POINTS
1. A199 Edinburgh Road
2. A1 Musselburgh By-pass
3. A6095 Newcraighall Road
4. Whitehill Road
5. A6106 The Wisp
6. A7 Old Dalkeith Road
7. A772 Drum Street
8. Lasswade Road
9a. A701 Burdiehouse Road
9b. Southhouse Broadway
10. A702 Biggar Road
11. Dreghorn Link
12. A70 Lanark Road
13. Baberton Junction
14. A71 Calder Road
14a. Edinburgh Park South Access
15. South Gyle Broadway
16. A8 Glasgow Road
17. A90n Queensferry Road