Here we have in Hong Kong three cross-harbour tunnels - pretty nearly perfect substitutes for each other since each gets you to somewhere on the other side of the harbour. So what would you think the price elasticity of demand for the western tunnel would be? Elastic, of course. That means raising prices is likely to mean a percentage fall in demand greater than the price increase and therefore a drop in total revenue.

The tunnel firm should try lowering tolls if it really wishes to increase revenue.

I can only surmise that the objective of the latest toll hike is not to raise revenue but to make congestion worse, so as to force the government's hand to buy out the Western Harbour Tunnel. All this still begs the question of why we have three tunnels all charging different tolls. The level of patronage - and hence, congestion - at each tunnel is totally predictable based on their relative prices. How these deals with the privately operated tunnel companies were negotiated should be seriously revisited. It would be better for the government to waste taxpayers' money to buy back the western tunnel than to listen to calls for a fourth tunnel as it can't even solve the relative pricing problem with three.

When might we expect our government to pay attention to basic economic principles in order to deal with the increasing number of obvious and predictable problems of mispricing, oligopoly and misallocation of resources that are raising doubts about the quality of governance here?

Celina Lin, Clear Water Bay

Simple and swift solution

The Hong Kong government needs to take quick and decisive action to deal with the imbalance in traffic among the three harbour tunnels. It is ridiculous that the traffic flow is being driven more by toll price than user need.

The resulting long queues at the Cross-Harbour Tunnel seriously damage Hong Kong's productivity and the environment, hurting us all. This is not rocket science, the key is to equalise toll prices.

Why not put in place a HK$15 toll increase at the Cross-Harbour Tunnel and use the money to fund a HK$15 toll rebate at the western tunnel?

Try it out for six months and tweak it if necessary.

It should not require years of bureaucratic and political wrangling to get this issue sorted out.

Steven Pang, Yuen Long

Plea for HK$20 two-week trial

I am frustrated by the apparent ineptitude of the Western Harbour Tunnel management in raising tolls again.

How can this make good economic sense? In this case, logic does not apply; the higher the tolls, the fewer vehicles will use the tunnel. Why is the tunnel underutilised? Because few can afford the tolls. I am a car driver living on Hong Kong Island. When I want to go to Kowloon, I first consider my destination and then the tunnel tolls. At HK$45, the western tunnel toll was high, but I only used it once every few months, so I was prepared to pay for the convenience.

However, for the vast majority of tunnel users, the primary concern is the toll fee. Drivers using crossings on a daily basis will nearly always take the cheapest tunnel. The toll can affect the profit margin of their businesses. Since this argument is seemingly so obvious, why is it that the western tunnel management does not see this?

If the tolls were halved, the number of vehicles using the tunnel would multiply and profits would skyrocket. If the managers do not believe me, I challenge them to try it for two weeks. Set the toll for cars at HK$20, the same as the Cross-Harbour Tunnel, and thousands of vehicles will switch to the western tunnel.

If this does not work, they can revert to high tolls.

Just think how much this policy would improve our clogged roads and our lives in general.

Peter Gill, Mid-Levels

Tighter control of signboards

I have been concerned at the sight of signboards dangling from buildings on the streets of Hong Kong, following recent heavy rainfall and strong winds.

These are not isolated sightings. I have seen them all over the city, even on busy streets like Nathan Road.

I think action should be taken immediately to deal with these signboards as they pose a threat to pedestrians.

As I understand it, the Buildings Department is responsible for overseeing the state of signboards. It has apparently sent out staff to keep an eye on them, but more must be done.

Abandoned signboards also create a problem. You see them advertising a shop or another business which is no longer operating from that building.

The boards are not properly maintained or cared for. They are extremely worn and eventually one will drop to the ground.

Abandoned or illegally or improperly installed signboards are not like some ailing trees - they are easy to spot.

I hope prompt action will be taken in the near future to deal with this problem before it is too late.

Vanessa Lee, Tsuen Wan

Warning has its limitations

I refer to James Middleton's letter ('Observatory's heat warnings do not give accurate temperature', July 19).

The very hot weather warning is generally effective to raise public awareness on the health risks associated with very hot weather.

It has been used for more than 10 years and is accepted and understood by the public.

On the suggested application of these warnings to the idling engine law, the Observatory has recently explained to legislators the operation of the warning, including its limitations.

The very hot weather warning was primarily designed to alert the public to very hot conditions and was not meant for tailor-made applications in specific sectors.

We are also aware of the inherent scientific constraint of forecast uncertainties, meaning there would be cases where the warning was in force but the actual weather conditions did not reach the warning thresholds, and cases where the warning was not in force but the thresholds were reached.

The Observatory recognises the public's need for heat-stress-related information to supplement the warning. We successfully applied the wet bulb globe temperature ('the temperature you feel when your skin is wet and is exposed to moving, humid air') during the 2008 Olympics equestrian events in Hong Kong.

The knowledge acquired and the technology developed are also to be shared in support of the Asian Games in Guangzhou later this year.

Building on the experiences gained, the Observatory is currently working with the relevant stakeholders to carry out intensive studies on how wet bulb globe temperature can be effectively adapted for use by the general public in Hong Kong.

Edwin S. T. Lai, senior scientific officer, Hong Kong Observatory

Why we need HK-Zhuhai link

Special economic zones established on the mainland pose a threat to Hong Kong's status as an international financial hub.

The most effective way to remedy this is to construct the Hong Kong-Zhuhai-Macau Bridge.

This project will be a boost to Hong Kong's logistics industries.

Our nine container terminals are reaching saturation point. That problem can be solved by having a more effective link between Hong Kong, Zhuhai and Macau. It will provide more business opportunities within the Pearl River Delta.

Hong Kong cannot stay in front by its own efforts. There must be a certain degree of co-operation with other governments in the region.

Of course, the protection of the Chinese white dolphins matters. While economic development is important, environmental protection issues cannot be neglected. Therefore, the government must come up with a strategy of sustainable development which will appease green groups.

There must be no further delays in this bridge project.

Jennifer Lam Nga-ching, Lam Tin

Not very good role models

The Trade Development Council banned the pseudo-models from any autograph-signing sessions at the Hong Kong Book Fair.

Some of the models and their teenage fans were not happy with this decision.

I do not think these young women can be seen as positive role models for their fans.

They have not acquired any professional training and they have sometimes expressed questionable opinions.

I hope that teenagers are able to see the pseudo-models for what they are and not harbour any illusions about them.

Andy Sze, Tsuen Wan