2018年1月20日 星期六

三跑成為「用不着的尿兜」已無懸念


14民航處張麗娟女士撰文(註1),指以「尿兜」比喻赤鱲角機場的三跑問題不恰當,又嘗試以2007年和2016年與內地簽署的文件,說服我們相信三跑建成後必有所需空域。可惜事實證明,赤鱲角機場啟用二十年,民航處手持2007年文件也已十年,連提高現有雙跑道升降量所需的空域都未能得到,第三條跑道(三跑)需要增加的空域就更不用說了。

「尿兜」之說源自我在網上社交平台的貼文(註23),某商廈男廁一端安裝了三個尿兜,空間卻只能站兩個人,多安裝的第三個尿兜(三兜)一點額外作用都沒有,我以這個方便說法,讓市民理解三跑同樣需要配以相連空域給飛機通過,才能夠發揮升降功能,沒有空域則三跑不能升降,只是石屎打造的裝飾品。

張文指以人在平面上的情況比喻飛機在三維空間飛行是失當的,又說在同一地理位置上容許多架飛機在不同高度層安全運作云云,既然張女士談立體幾何,我也深入多講一點。以三個尿兜為例,採取三維思維確實有令三兜發揮作用的方案,就是在兩個企位上空3高處建一個平台,連接一道從外圍架起的樓梯,讓第三個人走近和使用三兜,問題是廁所牆高不足6,建了平台人也走不上去,即是說引入三維空間也有制肘,不是「想點就點」,同理適用於三跑。
頭上的空間不是無限,立體空間也有制肘!
回到歷史,雙跑道的赤鱲角機場,原本設計的最高升降量是每小時86架次,但是直到不久之前還只是68架次,原因何在?原來當年的顧問假設進出赤鱲角機場的飛機可以使用所謂「北面航道」,例如內地來的飛機可以在珠江口低空南下直接左拐降落赤鱲角機場,起飛的飛機則可以東飛後左拐入大欖涌水塘上空,隨即在低空北上內地,以及在風向逆轉時以同樣航道反向起飛或降落,這樣的話,雙跑道可以同時起飛,同時降落,效率大增,不幸的是機場1998年啟用以來二十年,運作北面航道需要的空域始終沒有實現,以致顧問說的最高升降量變成空話,順便說一句:以顧問說的話作為「三跑有用」的論據是不可靠的,歷史已有證明。

香港北面的空間沒錯是三維,可惜赤鱲角北面航道與深圳機場以南的升降航道有根本矛盾,在雙方航道交叉的位置,航機垂直距離少於安全標準,這是空域問題十年沒有寸進的簡單原因,底抽薪的解決方法是深圳機場停止運作,可是1998年赤鱲角機場啟用時已因深圳機場不能使用北面航道,如今深圳發展到GDP即將超越香港,要求人家作出犧牲是妄想吧。

機管局建三跑的理據是升降量可達每小時102班,民航處也不斷以2007年的文件引導市民相信三跑建成後,它需要空域自然會出現,但是過去二十年的殘酷現實證明,這份文件連現有雙跑道需要的空域也擠不出來,遑論未來三跑?

張文嘗試以2016年文件裏的「循序漸進令香港三跑道系統達至最終每小時處理102班航班的長遠目標」叫我們放心,反映民航處人員稍欠閱讀內地官方文件的經驗,沒有看懂「循序漸進」、「最終」和「長遠目標」加起來的含義,它其實明白地說了:三跑建成之日赤鱲角機場肯定做不到102班水平!事實上,在沒有北面航道的背景下,連能否達到赤鱲角機場雙跑道原定的86班目標也成問題,在空域毫無把握的情況下興建三跑,是冒進和不科學的,像竉壞了的孩子以為父母會不顧一切遷就他一樣。

依目前形勢判斷,三跑建成之日,赤鱲角機場升降航班不能增加,三跑成為「用不着的尿兜」已無懸念。

林超英
香港中文大學地理與資源管理學系 

1     信報  2018年1月4:大幅拉提航機升降量  港建三跑是不二法門  http://bit.ly/2DysvAy
2     臉書《林超英 Lam Chiu Ying  2018年1月1貼文  http://bit.ly/2rrtayS
3     《草雲居》  2017年12月31 三個尿兜的故事


[信報 2018120刊出]

2018年1月17日 星期三

無聊研究系列 玄奘法師:出中國記



(1)  簡述

公元627年(貞觀元年)玄奘法師離開長安,經秦州、蘭州、涼州至瓜州,至此已是唐朝勢力邊緣,他單人匹馬出玉門關,穿越莫賀延磧至伊吾,這一帶當時歸入西突厥勢力範圍,由這裏開始,玄奘沿途由官方人員陪同,不再孤獨,他西行經南磧至高昌,逗留月餘後經阿耆尼至屈支,因冬季冰雪封山又逗留了兩個月,春季往跋祿迦,折向北行,翻越凌山,抵大清池南岸,西北行至素葉水城,會見了西突厥的葉護可汗,至此玄奘已經離開了現代中國的國境,完成了往古印度行程第一階段,此時已是貞觀二年。

本文藉着衛星圖片的詳細地理信息,補充前人的研究,以地圖展示玄奘從瓜州到素葉城的具體路線,以及點出與古籍地名對應的現代名稱和位置。

(2)  參考資料

本文的原始參考材料是玄奘和辯機合撰的《大唐西域記》,以及玄奘弟子慧立撰的《大唐大慈恩寺三藏法師傳》,以下簡稱《法師傳》。前者的西行記載由高昌開始,重點在介紹沿途的地理和風俗等,後者是玄奘的傳記,較多敍述西行途中的故事,從長安出發說起,兩者均有網上電子版(註12)。

本文也得力於季羡林等編寫的《大唐西域記校注》(註3),以下簡稱《校注》,他們花了極大氣力,考據中外眾多典籍,推論《大唐西域記》地名對應的外文名字及位置,對於斷定玄奘的行程有重大貢獻,可惜當時他們沒有現今互聯網上的浩瀚地理信息,尤其是衛星圖片,無法確定個別國、城的方位,以及往來各地的具體路線,留下了一些空白。

本文參考了互聯網最新高分辨率人造衛星圖片(Googlezoom.earth),從太空看山脈、河流、沙漠、綠洲、植被、農耕、城鎮、道路,以及從現代地圖取得當今的地方名稱,對比《大唐西域記》和《校注》的描述,加強了敲定各個國和城的位置的能力,需要時還利用了三維立體的地圖功能,判斷穿越群山的可行路線,提高確定玄奘行程路線的精度和可靠性。

(3)  長安至瓜州

玄奘由長安前往大唐國土邊緣途中,經過的城市古今名稱對照如下,都是較大或出名的城市,所以不作地圖顯示,可參看《中國史稿地圖集-下冊》(註4):

唐名
長安
秦州
蘭州
涼州
瓜州
今名
西安
天水
蘭州
武威
瓜州

歷史上敦煌和瓜州兩個地名,交替出現,唐之前的北魏時,敦煌是瓜州的治所,唐初分立為沙州,餘下的地域仍名為瓜州。唐代的沙州和瓜州相對於現在的敦煌市及瓜州縣(別名安西),衛星圖片可見是兩片相鄰的綠洲,玄奘的下一個目的地是綠洲小國伊吾,即今哈蜜。

(4)   瓜州至跋祿迦國

1  瓜州至跋祿迦國路線

瓜州至伊吾
《法師傳》稱玄奘在瓜州的玉門關附近偷渡出境,位置的描述如下:「從此北行五十餘里。有瓠蘆河下廣上狹,洄波甚急深不可渡,上置玉門關路必由之」。

一般人知道今敦煌以西的玉門關遺址,不過那是漢代所設的玉門關,唐初把玉門關移至瓜州,《法師傳》提到玄奘在瓜州時,「所從二小僧,道整先向燉煌,唯惠琳在,知其不堪遠涉亦放還」,說隨行的小僧道整去了敦煌(通燉煌),顯然當時敦煌(沙州)和瓜州已分為兩個行政區,玄奘只到了瓜州,沒有去敦煌,因此他經過的玉門關不是敦煌的玉門關,而是唐代新設在瓜州的玉門關。

考古學家相信今瓜州縣城東南62公里的鎖陽城遺蹟是唐代瓜州治所(註4),唐玉門關則定在疏勒河畔的雙塔堡一帶(註5),遺蹟淹沒在近代建的水庫裏,兩個地點的相對方位符合《法師傳》的描述,今疏勒河則對應《法師傳》的瓠蘆河。

2  個玉門關及玄奘出關路線
G: 今瓜州縣城   D: 今敦煌市
1: 唐玉門關   2: 鎖陽城遺址   3: 漢玉門關

《法師傳》稱玄奘「三更許到河遙見玉關,去關上流十里許,兩岸可闊丈餘 布草填沙。驅馬而過」,此處疏勒河水向西流,因此玄奘應在玉門關以東渡河,渡河後同行的胡人決定折返,玄奘自此單人匹馬上路,隨後的路線,《法師傳》形容為「關外西北又有五烽,候望者居之,各相去百里,中無水草,五烽之外即莫賀延磧伊吾國境」。

玄奘渡河後往伊吾的路線我們無法具體掌握,只知大概向西北,前段五百(唐)里玄奘需要到烽火台周邊的水源取水,所以應該在官方驛路附近前進,其後進入「長八百餘里,古曰流沙」的莫賀延磧,「磧」是乾旱的沙石地,「上無飛鳥,下無走獸,復無水草」,這段路玄奘走了五日五夜,幾乎渴死,幸而碰上「草池」,人馬休息一日後,再走兩日抵達伊吾

由瓜州玉門關往伊吾的直線距離較短,但是沿途地形比較複雜,如果循漢至隋經敦煌玉門關的走法,則在穿過玉門關和走過少許山區後,衛星圖片顯示沙漠中有南北走向的乾涸河道,應該是最不易迷路的路線,本來是玄奘往伊吾較合理的選擇,不過唐代玉門關需要東撤總有它的歷史背景,玄奘是沒有選擇的。

伊吾至焉耆
《法師傳》稱玄奘在伊吾停留了十多日後,應高昌王邀請,在眾多人馬護衛下,西行過天山山脈以南的南磧,「六日至高昌界白力城,時日已暮」,白力城即今鄯善縣,受國王催促,連夜「數換良馬前去」高昌王城,高昌故城遺址在今吐魯番市東南約30公里處。衛星圖片顯示今吐魯番、古高昌和今鄯善是天山南麓數個鄰近的小綠洲。高昌王隆重款待玄奘一個多月,為他寫了「介紹信」給西突厥可汗和路上各國,還提供大量金銀物資,以及派出人員陪同上路,《法師傳》:「為法師度四沙彌,以充給侍,製法服三十具,以西土多寒,又造面衣手衣靴等各數事,黃金一百兩,銀錢三萬,綾及絹等五百匹,充法師往還二十年所用之資,給馬三十匹,手力二十五人,遣殿中侍御史歡信送至葉護可汗衙,又作二十四封書,通屈支等二十四國,每一封書附大綾一匹為信,又以綾絹五百匹果味兩車」。

《大唐西域記》:「出高昌故地,自近者始,曰阿耆尼國,舊曰焉耆」,此地即今博斯騰湖西北的焉耆縣,玄奘在此僅度宿一宵。

往焉耆路上,在地理形勢的制約下,玄奘經過今吐魯番市,向南經過今托克遜,穿過天山餘脈的山口,然後轉向西行至今博斯騰湖西北的焉耆。

3  白力城至焉耆路線

鄯善至跋祿迦
《大唐西域記》:「從此西南行二百餘里,踰一小山,越二大河,西得平川,行七百餘里,至屈支國,舊曰龜茲」

「二大河」指從西北方注入博斯騰湖的開都河和源自該湖西南角向西流的孔雀河,「平川」則是自今庫爾勒起向西連綿數百公里、位於天山腳下的走廊地帶,得到天山溶雪水的滋養,沿途有大小不一的綠洲,屈支國即今庫車,

《法師傳》:「時為凌山雪路未開不得進發」,由於時值冬季,天山山脈積雪,玄奘不能跨越,於是在屈支逗留了「六十餘日」,《大唐西域記》:「從此西行六百餘里,經小沙磧,至跋祿迦國,舊謂姑墨,又曰亟墨」。跋祿迦即今阿克蘇地區,《校注》認為其都城在今溫宿縣,玄奘在此停宿一夜後,向凌山進發,踏上離開現代中國國境的艱難行程。

(5)   跋祿迦至素葉城

《大唐西域記》對於此段行程的記載如下:「(跋祿迦)國西北行三百餘里,度石磧,至凌山,此則葱嶺北原,水多東流矣。山谷積雪,春夏合凍,雖時消泮,尋復結氷。經途險阻,寒風慘烈,多暴龍,難淩犯,行人由此路者,不得赭衣持瓠大聲叫喚,微有違犯,災禍目覩,暴風奮發,飛沙雨石,遇者喪没,難以全生。山行四百餘里至大清池 清池西北五百餘里,至素葉水城。」(依《校注》版本)經過這段路程,玄奘進入了今吉爾吉斯國,當時則是西突厥地域。

《校注》稱「凌山當即冰山」和「溫宿之西北自古以來有二通道,一為木素爾達阪,一為勃達嶺,玄奘行記中的凌山,究竟何指,現學者之間尚無一致意見」。

我在另文(註6)詳細考據了地圖及人造衛星圖片,得出凌山是天山山脈西支,前往木素爾達阪(木札爾特山口)的入山口在圖4標記為”M”的位置,不符合「溫宿之西北」的描述,往勃達嶺(今別迭里山口)的入山口則在”B”,但是沿路沒有「水多東流矣」,經過仔細研究天山西支的山脈、河流,以及現今吉爾土斯及新疆的連接道路情況,推斷玄奘經圖中標記”b”的位置,進入烏宗圖什河(又稱瓊烏散庫什河)河谷,溯流北上,在較低海拔處繞過天山餘脈,經今Kara-say到大清池(今伊塞克湖)邊今Barskoon一帶。

跋祿迦至素葉城玄奘經行路線
H:汗騰格里峰   M:木扎爾特河出山口
B:往別迭里山口處  b:烏宗圖什河出山口

《校注》考據素葉水城「亦作碎葉城、素葉城,因碎葉水(Sūyāb,或作細葉水、睢合水)而得名,唐一度為安西四鎮之一」,”āb”在印歐語系內是水及河流的意思,Sūy是河流的名稱,碎葉水即今楚河(Chu River),近年考古研究推斷今吉爾吉斯國楚河河谷的托克馬克(TokmakTokmok)附近的遺蹟是西突厥時的碎葉城所在。

玄奘從沿着大清池南岸往西走,接上楚河後便可循河谷前往素葉水城,是當時西突厥統葉護可汗(Tong Yabghu Qaghan)的「衙所」,統葉護可汗在這裏與玄奘見了面,為他寫了給各國的介紹書,以及派出通曉各國語言人員護送玄奘到迦畢試國(今阿富汗Bagram),是進入古印度之前山中最後一個綠洲大國。

至此玄奘已經離開了現代中國的國境,完成了往古印度行程第一階段,此時已是公元628年(貞觀二年)。


1     《大唐西域記》CBETA電子版  中華電子佛典協會  http://buddhism.lib.ntu.edu.tw/BDLM/sutra/chi_pdf/sutra20/T51n2087.pdf
2     《大唐大慈恩寺三藏法師傳》CBETA電子版  中華電子佛典協會http://buddhism.lib.ntu.edu.tw/BDLM/sutra/chi_pdf/sutra20/T50n2053.pdf
3     《大唐西域記校注》  玄奘、辯機原著 季羡林等校注  中華書局 2000
4     絲綢之路世界遺產網站:鎖陽城遺址  http://www.silkroads.org.cn/portal.php?mod=topic&topicid=24
5     鄭明武、李妮著:絲路要道 玉門關   青萍果數據中心,2014

6     《草雲居》  2017821:玄奘法師跨越天山路線新考  http://tiandiyouqing.blogspot.hk/2017/08/blog-post_21.html

2018年1月10日 星期三

在交通運輸用地上興建樓房 - 給土地供應專責小組的意見書


我向政府土地供應專責委員會遞交了一份意見書(見下),以外國及香港的例子,說明在交通運輸用地上興建樓房是快捷和便宜的增加房屋土地供應的選項,關鍵是以立體思維去進行城市規劃。

事實上,香港近年已經有不少先例,同一片土地上的不同高度用作雨種不同用途,如架空馬路穿過油麻地停車場、紅磡站和多個地鐵站上蓋的住宅與商場、岩洞下的配水庫、污水廠和垃圾轉運站等,所以可以說立體規劃在香港已是既定政府政策,我的建議只是把它具體化到在交通運輸用地上建屋而己。

意見書裏舉例的五個選址,合共可提供近50公頃的建屋土地,不可謂少,而且香港還有其他地方可作同樣一地兩用,提供更多建屋土地,因此強烈建議專責小組在今年展開的公眾諮詢,即行政長講過的「大辯論」中,把在文通運輸用地上建屋列為給香港市民選擇的土地供應選項。

如果專責小組連填掉淡水湖都列為選項,則沒有理由把這個可行、快捷和便宜的方案拒諸門外,期望小組以香港人福祉為念,接受這個其實世界早有先例的增加土地供應方案。

          =                    =                    =                    =                    =

Paper for Task Force on Land Supply

Housing Development Above Transport Infrastructure As A Land Option

Submitted by:
Lam Chiu Ying, Adjunct Professor
Geography and Resource Management Department
Chinese University of Hong Kong
9 January 2018


1.      Introduction
a.       This paper follows up on the suggestion given in paragraph 12 (b) 2 of the paper dated 1 August 2017, submitted by the Hong Kong Countryside Foundation to the Chief Executive and relevant policy secretaries.  The TFLS secretariat notified HKCF on 28 December 2017 that the paper was circulated to TFLS members.
b.      That paragraph advocates that Government and the Task Force on Land Supply should take up the option of securing land for housing by making use of “potential podiums above infrastructure, utilities, highways, railways, and roadside areas”.
c.       This paper explains that this option could release significant amounts of land within a shorter time frame than many other options.  It is shown by way of examples that sizable pieces of land currently occupied by transport infrastructures exist, which are large enough to accommodate typical public housing estates so long as one is prepared to think out of the box and adopts a 3-dimensional approach to land zoning.
d.      TFLS is urged to present this recommendation of the Hong Kong Countryside Foundation as an option for the public to consider and prioritize in the coming comprehensive public consultation.

2.      The concept
a.       Traditional town planning assigns land use zones on a two-dimensional plan.  In Hong Kong, only one land use label is applied to each zone marked on Outline Zoning Plans published by Government.  It serves as the basis of the administrative and enforcement work of Planning Department and Lands Department.
b.      However, as land resource becomes scarce in densely populated cities, a pattern has emerged in which two or more different uses are stacked on the same footprint in many countries.  Examples are public parks, commercial plaza and residential building built above roads and highways.  This amounts to the adoption of a 3-dimensional approach to town planning, in which vertical partition of space is implemented to accommodate diverse uses of land..
c.       In Hong Kong, the concept of transport infrastructure and other land uses co-existing above the same footprint is not new.  A well-known example is the elevated road which runs through Yaumatei Carpark Building.  Several housing projects are built on the land of railway stations and depots.  An early example is the Metropolis Residence Towers above Hunghom Station.  Nowadays, many building developments sit on top of MTR stations.
d.      HKCF’s recommendation to build on podiums above highways, railways, etc. is a manifestation of this 3-d town planning approach.  The key is to enable residential/commercial/public uses and transport infrastructure share the same footprint but occupy different vertical levels.

3.      Advantages of the concept
  1. Recent advocates for more extensive applications of this concept in Hong Kong include Vincent Ng, ex-President of Hong Kong Institute of Architects.  The advantages of the concept are “quick supply of land, quick improvement to environment of the district and savings in the development of land resource” (ref.1).
  2. Land occupied by roads and railways is brown-field land.  The use of such land for housing development conforms to the “brown field site first” principle.  Thus it would reduce potential opposition from people concerned with conservation.
  3. Furthermore such sites are typically Government land so that no land resumption is required.  The development of such sites may proceed in earnest without complications arising from negotiations with private land owners or tenants.
  4. There is no need to incur any expense of the same order of magnitude as reclamation in remote parts of Hong Kong waters.  There is also no need to build major transport infrastructure since road and railway transport are already there.  Development on transport infrastructure land is thus a much cheaper option than reclamation.

4.      Overseas Examples
  1. Many examples already exist elsewhere in the world.  An example involving an area of around 10 hectares is found in Boston, USA.  Over a stretch of about 800 metres above Interstate 90, a platform is formed to accommodate a cluster of buildings, including residential apartments, hotels, commercial buildings, shopping malls and open space.  Among them is Prudential Tower, a 52-storey building with 110,000 sq. metres of floor area.  It shows that development of this scale above roads is feasible in engineering terms and that building above roads for residential purpose is practical.


Boston (A:Prudential Tower; B: Copley Place)

  1. Another example of a smaller scale is the Washington State Convention Center in Seattle.  It sits on a platform of around 2 hectares formed above Interstate-5.


The eastern portion of Washington State Convention Center (W) stands astride Interstate-5

5.      Potential sites in Hong Kong for housing development above transport infrastructure

a.       MTR Pat Heung Depot
Area: about 20 hectares.  The site could comfortably accommodate the equivalent of Kwong Fuk Estate and Wang Fuk Garden in Tai Po.



b.      Coastal strip at Ma Liu Shui near the Chinese University of Hong Kong
      Area: about 3 hectares.  The site is only slightly smaller than that of Wo Che Estate in Sha Tin.



c.       Large roundabout in Yaumatei
      Area: about 10 hectares.  The site is large enough to accommodate So Uk Estate in Shamshuipo.




d.      Road junction south-east of Mei Foo Sun Chuen
      Area: about 8 hectares.  The site is only slightly smaller than the southern half of Mei Foo Sun Chuen.



e.       Road network between Mei Foo Sun Chuen and the Container Port (including some open-air car parks)
      Area: about 8 hectares.  The site is only slightly smaller than the southern half of Mei Foo Sun Chuen.



6.      Likely objections
  1. It is understood that Lands Department has traditionally opposed the concept of developments above roads which reflects adherence to the 2-dimensional understanding of land zoning.  But it is no longer in keeping with prevailing circumstances in which Government’s established policy has shifted towards allowing different uses to occur at the same site.  This established policy position is amply confirmed by residential development projects above MTR stations, underground flood-water buffer reservoirs beneath playing fields in Happy Valley and Tai Hang Tung, and the use of caverns to house government facilities (such as sewage treatment works, service reservoirs, refuse transfer stations).
  2. Air pollution from cars may be said to be a concern.  But the Boston example has shown that this could be managed.  Anyway, numerous Hong Kong residential buildings are located right next to busy roads.  Air pollution cannot be treated as a deterring factor.
  3. Engineering difficulties may be quoted as another cncern.  However both examples from Boston and Seattle show that substantial buildings can be constructed above major roads of considerable width.  Furthermore the difficulty and cost are definitely less than re-provisioning a container port, a proposal which the Task Force on Land Supply appears to be willing to present to the public as an option for land supply.

7.      Conclusions and Recommendations to TFLS
  1. From the above discussions and the examples from overseas and locally, it is clear that building above transport infrastructure is a quick, cheap and engineering-feasible option to secure sites of significant size for housing development. 
  2. The five potential sites presented in this paper alone would provide some 50 hectares of land which are easily accessible by public transport and therefore favourably located for housing development.  They could therefore serve as short- to medium-term solutions for increasing land supply in Hong Kong.  It is believed that more sites of similar nature could be identified given more effort.
  3. It is therefore recommended that TFLS:
                                    i.        Take note of and affirm the established policy of allowing different land uses stacked vertically above selected land parcels, that is, the application of 3-dimensional approach to town planning;

                                  ii.        Urge Government to:
1.          instruct Planning Department and Lands Department to adapt themselves in recognition of the established policy of 3-d town planning and vertical stacking of land uses;
2.          study the five potential sites and to identify further sites in Hong Kong suitable for housing development above transport infrastructure;

                                iii.        Adopt housing development above transport infrastructure as a land-supply option to be presented to the public in the coming consultation exercise to seek public views and to establish consensus on the prioritization of various land supply options.


References


1.  吳永順 Facebook Notes  2015年11月14「以立體思維規劃高密度都市」  http://bit.ly/2DyWSmU  內容提到:「可考慮在可行情況下,在公路及鐵路上加建社區、商業及綠化公共空間。此舉不但能在短期內提供土地及改善區內環境,亦能節省開發土地的資源