環(huán)境基礎(chǔ)設(shè)施城市化初探

劉志強(qiáng) 朱文一

環(huán)境（Environment）與人類生存關(guān)系密切，包括自然環(huán)境與社會(huì)環(huán)境。環(huán)境基礎(chǔ)設(shè)施（Environment Infrastructure）是指為城市環(huán)境保護(hù)與生態(tài)建設(shè)提供服務(wù)而建設(shè)的設(shè)施。環(huán)境基礎(chǔ)設(shè)施城市化（Environment Infrastructure Urbanism）是指隨著城市發(fā)展，環(huán)境基礎(chǔ)設(shè)施的使用現(xiàn)狀況發(fā)生改變，包括環(huán)境基礎(chǔ)設(shè)施形式的變化和使用功能的轉(zhuǎn)變。環(huán)境基礎(chǔ)設(shè)施包括園林、綠化地與環(huán)衛(wèi)設(shè)施3個(gè)子類（圖1），其中，園林主要是指各類公園，包括植物園、動(dòng)物園、郊野公園以及雕塑公園等；綠化地主要是指城市中的綠色空間，包括由草坪、林帶、行道樹(shù)、防護(hù)綠地、苗圃等組成的城市綠帶系統(tǒng)與各種公共綠地；環(huán)衛(wèi)設(shè)施是指為提升城市環(huán)境衛(wèi)生服務(wù)的基礎(chǔ)設(shè)施，包括垃圾處理設(shè)施、公共廁所與其他市容與環(huán)境衛(wèi)生設(shè)施。

與交通基礎(chǔ)設(shè)施、水利基礎(chǔ)設(shè)施、能源基礎(chǔ)設(shè)施相比，環(huán)境基礎(chǔ)設(shè)施的城市化與城市生態(tài)建設(shè)的關(guān)系更加密切，可以說(shuō)，環(huán)境基礎(chǔ)設(shè)施城市化的過(guò)程就是一個(gè)城市生態(tài)化的過(guò)程。因而，與交通基礎(chǔ)設(shè)施、水利基礎(chǔ)設(shè)施、能源基礎(chǔ)設(shè)施相比，設(shè)計(jì)師在介入環(huán)境基礎(chǔ)設(shè)施城市化的過(guò)程中，應(yīng)當(dāng)從自然環(huán)境切入，其設(shè)計(jì)過(guò)程是對(duì)于自然資源的整合與優(yōu)化。從這個(gè)角度來(lái)講，環(huán)境基礎(chǔ)設(shè)施城市化的理想狀態(tài)是實(shí)現(xiàn)“原生態(tài)”。隨著環(huán)境基礎(chǔ)設(shè)施城市化進(jìn)程的推進(jìn)，環(huán)境基礎(chǔ)設(shè)施的“設(shè)施”屬性將越來(lái)越弱，因而，我們又可以說(shuō)，環(huán)境基礎(chǔ)設(shè)施城市化的過(guò)程就是一個(gè)去“設(shè)施”屬性的過(guò)程，或者說(shuō)是一個(gè)“自然”化過(guò)程。在這個(gè)過(guò)程中，傳統(tǒng)意義上的綠化將逐步走向“荒野”（圖2）。“簡(jiǎn)而言之，荒野和城鎮(zhèn)是共生關(guān)系，城鎮(zhèn)依賴于荒野提供的原材料，而荒野依賴于城鎮(zhèn)提供的消費(fèi)[1]?！边@段話揭示了環(huán)境基礎(chǔ)設(shè)施城市化過(guò)程中其與自然間的關(guān)系，而最終，隨著技術(shù)與意識(shí)的進(jìn)步與統(tǒng)一，這樣的共生關(guān)系將走向共融。本文基于此構(gòu)想，依托傳統(tǒng)環(huán)境基礎(chǔ)設(shè)施的分類，結(jié)合環(huán)境基礎(chǔ)設(shè)施的發(fā)展情況，討論了目前環(huán)境基礎(chǔ)設(shè)施城市化的情況，探索環(huán)境基礎(chǔ)設(shè)施城市化的可能性。

圖1 / Figure 1Category of Infrastructural Urbanism of Environment Infrastructure環(huán)境基礎(chǔ)設(shè)施城市化類別來(lái)源/Source:作者自繪

城市公園（City Garden）是指將城市基礎(chǔ)設(shè)施轉(zhuǎn)變功能用作公園，成為城市公園體系的一部分。隨著基礎(chǔ)設(shè)施城市化的進(jìn)行，基礎(chǔ)設(shè)施將成為城市公園體系構(gòu)成的重要來(lái)源之一。在此背景下，城市公園的功能定位也將發(fā)生變化，在未來(lái)很長(zhǎng)一段時(shí)間內(nèi)，城市公園與社區(qū)的關(guān)系將變得更加密切，中心城區(qū)的基礎(chǔ)設(shè)施用地為實(shí)現(xiàn)城市公園與社區(qū)的整合提供了可能性。這樣的城市公園將成為社區(qū)活動(dòng)的場(chǎng)所，提升社區(qū)的活力。相較于傳統(tǒng)城市公園而言，環(huán)境基礎(chǔ)設(shè)施城市化背景下的城市公園設(shè)計(jì)在功能上將呈現(xiàn)兩個(gè)極端，對(duì)于特殊群體的設(shè)計(jì)將趨向高度對(duì)象化，即根據(jù)某類群體的特點(diǎn)進(jìn)行定制化設(shè)計(jì)，這也使得空間將呈現(xiàn)很高的識(shí)別性；另一個(gè)極端是在進(jìn)行場(chǎng)地設(shè)計(jì)時(shí)，將最大限度地保留場(chǎng)地的適應(yīng)性，這樣的適應(yīng)性設(shè)計(jì)將豐富公園的活動(dòng)類型，有利于提升城市公園輻射范圍內(nèi)社區(qū)的活力。

克萊德沃倫公園（Klyde Warren Park）位于美國(guó)達(dá)拉斯，建立在得克薩斯州最繁忙的Woodall Rodgers高速路之上，面積為20,000平方米。Woodall Rodgers高速路是橫亙?cè)谶_(dá)拉斯市中心、藝術(shù)區(qū)和北部居民區(qū)之間的屏障，它割裂了人口密集的北部社區(qū)與達(dá)拉斯市中心和北部居民區(qū)之間在空間上的聯(lián)系，而克萊德沃倫公園的建設(shè)解決了這個(gè)問(wèn)題，重新恢復(fù)了這一地區(qū)的連接（圖3上）。公園的建設(shè)資金來(lái)自于聯(lián)邦、州、市與個(gè)人4個(gè)不同群體范圍，它不僅重新整合了城市面貌，還為周邊的博物館和商業(yè)設(shè)施提供了一處綜合型戶外活動(dòng)場(chǎng)地?？巳R德沃倫公園落成后深受周邊社區(qū)居民的歡迎，它能夠獲得成功的重要原因之一在于其豐富的活動(dòng)類型能夠滿足不同群體的需求。在施工過(guò)程中，公園的一側(cè)設(shè)置了“食物卡車”來(lái)代替正在建設(shè)的餐廳為人群提供服務(wù)，由于“食物卡車”十分受歡迎，在餐廳落成后，它們得到了保留，并根據(jù)卡車的位置重新調(diào)整了鋪地，使得這里成為一個(gè)獨(dú)立而完整的永久性設(shè)施，這方便了通勤的人群，使得公園與周邊社區(qū)產(chǎn)生聯(lián)系。公園內(nèi)還設(shè)置有寵物狗公園，這個(gè)由土坡結(jié)合植物構(gòu)成的供遛狗者專用的公園同樣深受社區(qū)居民歡迎，因而管理者將其擴(kuò)張?zhí)嵘狭巳粘?。此外，公園內(nèi)還設(shè)計(jì)了兒童活動(dòng)區(qū)，活動(dòng)區(qū)的設(shè)計(jì)以營(yíng)造探索感為核心，設(shè)置了大大小小符合兒童活動(dòng)尺寸的土坡和可以鉆行的設(shè)施（圖3下），圓潤(rùn)的造型在最大限度保證兒童安全的同時(shí)也使得空間十分具有識(shí)別性，活動(dòng)區(qū)還設(shè)置有一條毛毛蟲式的噴泉，通過(guò)噴氣裝置模擬了一條毛毛蟲，作為蝴蝶噴泉的組成部分，它具有“化繭成蝶”的寓意，這個(gè)充滿趣味性的互動(dòng)式空間成為公園中人氣最高的場(chǎng)所之一。此外，公園中還有一處可同時(shí)容納5,000人的大草坪，草坪具有相當(dāng)?shù)倪m應(yīng)性，它可以成為小型音樂(lè)會(huì)的舉辦場(chǎng)地，也可以作為居民周末野餐的場(chǎng)所。公園的一側(cè)通過(guò)結(jié)合種植的橡樹(shù)林和樹(shù)枝形燈架，兩側(cè)布置座椅，提供報(bào)刊亭和各類棋盤游戲，形成一條休閑內(nèi)街。克萊德沃倫公園的建設(shè)也促進(jìn)了周邊地區(qū)的經(jīng)濟(jì)發(fā)展，使得周邊房屋的租金收益得以上漲，不同地區(qū)的租金上漲從30%～60%不等，而其旁邊的一處未開(kāi)發(fā)土地的價(jià)值也在公園建成后上漲到原來(lái)的3倍。

圖2 / Figure 2荒野Wilderness來(lái)源/Source:http://blog.hankchristensen.com/wp-content/uploads/2016/08/gem-lake-emigrantwilderness-124171.jpg

圖3 / Figure 3克萊德沃倫公園上:公園與周邊環(huán)境 / 下:公園兒童活動(dòng)設(shè)施Klyde Warren ParkTop: Contaxt of Klyde Warren Park / Bottom: KlydeWarren Park Children's Activity Facilities來(lái)源/Source:（上/Top）https://www.ojb.com/project/klyde-warren-park（下/bottom）https://www.ojb.com/project/klyde-warren-park

動(dòng)物廊道（Animal Corridor）是指為保護(hù)動(dòng)物遷徙所設(shè)計(jì)的路上通道。動(dòng)物廊道可以是動(dòng)物園的組成部分，也可以是為恢復(fù)自然狀態(tài)下被人工設(shè)施割裂而設(shè)計(jì)的遷徙廊道。之所以將動(dòng)物廊道作為環(huán)境基礎(chǔ)設(shè)施城市化中重要的一種類型，一方面是因?yàn)閯?dòng)物廊道在很多情況下是野生動(dòng)物園中的重要組成部分，另一方面則是因?yàn)槠湫问脚c內(nèi)容上呈現(xiàn)出自然原生態(tài)，符合環(huán)境基礎(chǔ)設(shè)施城市化的定義。

圖4 / Figure 4休斯頓紀(jì)念公園上:公園的連接 / 下:公園跑步中心與雨水滯留區(qū)Houston's Memorial ParkTop: Connetcion of Houston's Memorial Park /Bottom: Running Center and Rainwater Retention Area of Houston's Memorial Park來(lái)源/Source:http://www.nbwla.com/projects/park/memorial-park

圖5 / Figure 5休斯頓河灣綠道系統(tǒng)規(guī)劃上:愿景與現(xiàn)實(shí) / 下:規(guī)劃的經(jīng)濟(jì)價(jià)值Bayou Greenways Master PlanTop: Realizing and Vision of Bayou Greenways/Bottom: The Value of Bayou Greenways Master Plan來(lái)源/Source:http://www.swagroup.com/projects/bayou_greenways/

圖6 / Figure 6北京園博園公園上:公園與周邊環(huán)境 / 下:公園深坑景觀Beijing Garden Expo ParkTop: Contaxt of Beijing Garden Expo Park / Bottom:Beijing Garden Expo Park Deep Pit來(lái)源/Source:http://www.huitu.com/photo/show/20131125/221646546200.html

圖7 / Figure 7波士頓翡翠項(xiàng)鏈公園上:公園平面圖 / 下:公園與城市關(guān)系Emerald NecklaceTop: Master Plan / Bottom: Necklace in the City來(lái)源/Source:（上/top）http://www.greeningthegray.org/wp-content/uploads/2013/04/emerald-necklace.jpg（下/bottom）http://www.touristsbook.com/boston/fi les/2014/11/Emerald-Necklace-Boston-1000x600.jpg

休斯頓紀(jì)念公園位于610環(huán)路內(nèi)側(cè)，南側(cè)以布法羅河為邊界，向東距離休斯頓市中心6.5km。這里曾經(jīng)是一戰(zhàn)時(shí)期士兵的訓(xùn)練場(chǎng)，戰(zhàn)后為了紀(jì)念因戰(zhàn)爭(zhēng)而戰(zhàn)死的士兵建立此公園。然而，由于道路和分布在自然保護(hù)區(qū)中的休閑活動(dòng)空間長(zhǎng)期割裂紀(jì)念公園，使得公園的生態(tài)系統(tǒng)與空間質(zhì)量每況愈下。為了改善這樣的情況，Nelson Byrd Woltz Landscape Architects事務(wù)所對(duì)公園進(jìn)行了重新規(guī)劃，新規(guī)劃中的一個(gè)重點(diǎn)便是規(guī)劃了多條重新連接被道路分割的公園的動(dòng)物廊道（圖4上）。公園的新規(guī)劃在對(duì)該地深入調(diào)研的基礎(chǔ)上，確立了通過(guò)進(jìn)行多樣化植物種植恢復(fù)場(chǎng)地原生生態(tài)的設(shè)計(jì)理念。這與人們普遍希望恢復(fù)之前松林密布的想法不同，因?yàn)榻?jīng)過(guò)調(diào)研證實(shí)，松樹(shù)作為外來(lái)物種，并不適合在此進(jìn)行種植，相較于單一樹(shù)種組成的松林，多樣化的生物組成將更有助于抵御未來(lái)的水旱災(zāi)害，保持場(chǎng)地的生態(tài)穩(wěn)定性。設(shè)計(jì)人員將公園空間分為3種類型，一部分通過(guò)具體實(shí)施和管理實(shí)現(xiàn)生態(tài)的多樣性，另一部分通過(guò)維持與保護(hù)，最后一部分則通過(guò)新建與從地區(qū)遷出實(shí)現(xiàn)。動(dòng)物廊道的建立對(duì)于生態(tài)多樣性的實(shí)現(xiàn)至關(guān)重要，空間上的聯(lián)通使得自然狀態(tài)下物種的傳播具有了可能性，從而助力恢復(fù)原生生態(tài)目標(biāo)的實(shí)現(xiàn)。而相關(guān)科學(xué)數(shù)據(jù)與資料研究表明，在過(guò)去的數(shù)百年間，南側(cè)公園自然與人類占領(lǐng)的空間此消彼長(zhǎng)，兩者你退我進(jìn)、你進(jìn)我退，相互影響，始終未達(dá)到穩(wěn)定的狀態(tài)，而這意味著動(dòng)物廊道的建設(shè)與生態(tài)多樣性的實(shí)現(xiàn)潛力極大。作為動(dòng)物廊道的延續(xù)，沿布法羅河形成了休斯頓公園跑步中心與雨水滯留區(qū)（圖4下），這為人們?nèi)粘Ｅc公園發(fā)生關(guān)系提供了空間上的支撐，也可以看出設(shè)計(jì)者對(duì)于人與自然關(guān)系的思考。

綠帶（Greenbelt）是指一個(gè)帶形或線性的綠色開(kāi)敞空間，綠帶不僅作為一種應(yīng)對(duì)城市無(wú)限蔓延的手段，同時(shí)為居民提供活動(dòng)和游憩的生態(tài)圈，在保持城市與鄉(xiāng)村可持續(xù)發(fā)展方面起到重要作用[2]。本文的綠帶對(duì)應(yīng)基礎(chǔ)設(shè)施中的林帶、防護(hù)綠地、行道樹(shù)等類型，綠帶可以由這些元素構(gòu)成，但單一的元素未必一定會(huì)形成綠帶。與霍華德的綠帶概念相比，基礎(chǔ)設(shè)施對(duì)應(yīng)的綠帶現(xiàn)階段更加關(guān)注其連接性，如何將現(xiàn)有的線性環(huán)境基礎(chǔ)設(shè)施片段連接成為綠帶，連接綠地空間，構(gòu)建城市綠地系統(tǒng)并提升沿線社區(qū)的生態(tài)性是現(xiàn)階段環(huán)境基礎(chǔ)設(shè)施城市化關(guān)注的重點(diǎn)。

休斯頓河灣綠道系統(tǒng)規(guī)劃是建立在Arthur Comey1931年的報(bào)告《休斯頓，實(shí)驗(yàn)性城市發(fā)展計(jì)劃》的基礎(chǔ)上于近年形成的一條長(zhǎng)度近500km的線性公園系統(tǒng)（圖5上）。新的公園系統(tǒng)將該地區(qū)范圍內(nèi)10條水道重新連接，惠及的人口數(shù)量達(dá)到近200萬(wàn)人。根據(jù)德克薩斯大學(xué)John Crompton教授的研究估算，休斯頓河灣綠道系統(tǒng)綠道規(guī)劃每年將帶來(lái)的包括經(jīng)濟(jì)、環(huán)境與身體及精神健康方面的多項(xiàng)收益超過(guò)1.17億美元（圖5下）。休斯頓雖然具有公園空間與步行系統(tǒng)，但由于市內(nèi)缺乏明確分區(qū)，導(dǎo)致了未能在這些節(jié)點(diǎn)空間之間形成連接空間，因而使得這些公園與步行系統(tǒng)十分分散，這也直接導(dǎo)致了全美第四大城市的休斯頓城市公園系統(tǒng)面積常年位于全國(guó)城市的下游水平。河灣綠道項(xiàng)目是改善此種狀況的一個(gè)契機(jī)，它將使得休斯頓城市公園間得以建立連接并為城市提供數(shù)量可觀的休閑空間，整合現(xiàn)有公共資源，為周邊社區(qū)居民提供寶貴的生態(tài)化公共活動(dòng)空間。

垃圾處理設(shè)施（Garbage Disposal Facilities）是指將工業(yè)、生活生產(chǎn)、醫(yī)療衛(wèi)生等產(chǎn)生的垃圾集中進(jìn)行回收處理的場(chǎng)所及其設(shè)施。垃圾處理設(shè)施中最為重要的一種類型是城市垃圾處理場(chǎng)，常見(jiàn)的垃圾處理方式包括衛(wèi)生填埋法、堆肥法和直接焚燒法等。填埋區(qū)易產(chǎn)生沼氣、含毒污水, 對(duì)空氣、土壤和地下、地表水產(chǎn)生污染[3]。城市垃圾處理設(shè)施中填埋場(chǎng)占據(jù)了重要的地位，數(shù)量眾多。所以，在環(huán)境基礎(chǔ)設(shè)施城市化過(guò)程中，如何對(duì)待這些垃圾處理場(chǎng)成為設(shè)計(jì)師面臨的重要課題。由于這些垃圾場(chǎng)本身面臨嚴(yán)重的土壤污染，因而，在對(duì)其進(jìn)行城市化設(shè)計(jì)的過(guò)程中應(yīng)當(dāng)更多地考慮其土壤自身的凈化。就目前來(lái)看，采用相關(guān)生態(tài)技術(shù)，將其用作城市生態(tài)公園，通過(guò)土壤中微生物的降解作用，恢復(fù)被污染的土壤是普遍采用的方式。

北京園博園公園（圖6上）是由原本被稱為“永定河大沙坑”的北京著名建筑垃圾場(chǎng)改造而成，園博園陸地面積267公頃，加上246公頃的園博湖，總面積513公頃[4]。原本臭名昭著的垃圾場(chǎng)，因?yàn)槌Ｄ晏盥窠ㄖ?，形成?0米的深坑（圖6下），通過(guò)巧妙的景觀設(shè)計(jì)，利用此高差建成了下沉式花木景區(qū)錦繡谷，形成瀑布跌水景觀[5]。另外，采用水源凈化工程，引入生物浮床、表流濕地、替流濕地等，建設(shè)生態(tài)濕地，凈化了永定河的水質(zhì)，也使得土壤環(huán)境得以改善[5]。園內(nèi)的5個(gè)展園：傳統(tǒng)展園、現(xiàn)代展園、創(chuàng)意展園、濕地展園和國(guó)際展園經(jīng)過(guò)精心的景觀與建筑設(shè)計(jì)，這樣的設(shè)計(jì)極大提升了原本地處城鄉(xiāng)交界帶位置的景觀水平。北京園博園的建設(shè)改善了生態(tài)環(huán)境，將原本無(wú)人問(wèn)津的垃圾場(chǎng)變成了城市綠肺[5]。

公共綠地（Green Area）是指城市中適用于居民游憩休閑的成片綠色空間，如果說(shuō)綠帶最大的形態(tài)特征是其線性空間形態(tài)，那么，公共綠地則呈現(xiàn)面狀形態(tài)，它與綠帶共同構(gòu)成城市公共綠色空間系統(tǒng)。

作為景觀設(shè)計(jì)的奠基人之一奧姆斯特德的代表作品，波士頓翡翠項(xiàng)鏈公園體系形成了園中有城、城中有園的效果（圖7上），這座城市公園使得波士頓成為了一座公園城市（圖7下）。公園利用河流等自然要素作為其邊界，加上16km長(zhǎng)的綠道系統(tǒng)，形成了450公頃的城市公共綠地，綠地系統(tǒng)由9個(gè)城市公園組成，每個(gè)公園的主題各異，包括城市公園、公共花園、沼澤地等不同形式，公園與城市生活相融，為居民提供連續(xù)的健身和休閑娛樂(lè)場(chǎng)所。公園因地制宜，利用地形的起伏形成具有適應(yīng)性的層次豐富的開(kāi)敞城市綠地，結(jié)合天鵝湖等水面，開(kāi)發(fā)水上活動(dòng)，形成豐富的城市活動(dòng)。

環(huán)境基礎(chǔ)設(shè)施的城市化過(guò)程就是城市的生態(tài)化過(guò)程，這個(gè)過(guò)程要求我們從根本上改變過(guò)去對(duì)環(huán)境基礎(chǔ)設(shè)施的認(rèn)識(shí)。環(huán)境基礎(chǔ)設(shè)施設(shè)計(jì)與建設(shè)的出發(fā)點(diǎn)與落腳點(diǎn)要始終以自然作為參考，最大限度地恢復(fù)自然的原生生態(tài)，同時(shí)，作為基礎(chǔ)設(shè)施，它又要為滿足人們的基本需求服務(wù)，而這實(shí)際上反映了“天人合一”的思想。環(huán)境基礎(chǔ)設(shè)施的城市化將成為城市與自然相結(jié)合的切入點(diǎn)，優(yōu)秀的環(huán)境基礎(chǔ)設(shè)施設(shè)計(jì)將為提升社區(qū)活力與增強(qiáng)社區(qū)生態(tài)性作出貢獻(xiàn)。

A Study on the Infrastructural Urbanism of Environment Infrastructure

LIU Zhiqiang

Environment is closely related to human existence,including the natural environment and the social environment. Environment infrastructure refers to facilities built to provide services for urban environmental protection and ecological construction.Environment infrastructural urbanism refers to changes in the use of environment infrastructure as the city develops, including changes in the form of environment infrastructure and changes in the use of functions. The environment infrastructure is consisted of three sub-categories, including gardens, green areas and sanitation facilities. Among them, gardens mainly refer to various types of parks, including botanical gardens, zoos, country parks and sculpture parks. Green areas mainly refer to green spaces in cities, including urban green belt system consisting of lawns, forest belts, street trees, protective green spaces, nurseries, etc. and various public green spaces. Sanitation facilities refer to the infrastructure for improving urban environmental sanitation services,including garbage disposal facilities, toilets and other cityscapes and environments health facilities.

Compared with transportation infrastructure, water infrastructure and energy infrastructure, the urbanization of environment infrastructure is more closely related to urban ecological construction. It can be said that the process of urbanization of environment infrastructure is a process of urban ecologicalization.Therefore, compared with transportation infrastructure, water infrastructure and energy infrastructure,designers should start from the natural environment in the process of intervening in the urbanization of environment infrastructure. The design process is the integration and optimization of natural resources. From this perspective, the ideal state of urbanization of environment infrastructure is to achieve “original ecology”. With the advancement of environment infrastructure urbanization, the characteristics of facilities of environment infrastructure will be reduced. Therefore, we can say that the process of urbanization of environment infrastructure is a process of “de-facilities”, or It is said to be a“natural” process. In this process, the greening in the traditional sense will gradually move toward the“wilderness” (Figure 2). “In short, wilderness and towns are symbiotic relationships, towns depend on the raw materials provided by the wilderness and wilderness depends on the consumption provided by the towns.” This passage reveals the relationship between environment infrastructure and nature in the process of environment infrastructural urbanism. In the end, with the advancement and unity of technology and consciousness, such symbiotic relationship will move toward communion. Based on the concept above and the classification of traditional environment infrastructure, combined with the development of environment infrastructure, this paper discusses the current urbanization of environment infrastructure and explores the possibility of environment infrastructural urbanism.

City Garden refers to the use of urban infrastructure transformation functions as a park and as part of the urban park system. As infrastructure urbanization progresses, infrastructure will become an important source of city garden systems. In this context,the functional orientation of city garden will also change. In the future, the relationship between city garden and communities will become closer. The infrastructure land in the central urban area will provide the integration of city garden and communities.Klyde Warren Park is a good example of this kind of infrastructural urbansim.The Woodall Rodgers Highway is a barrier between the heart of Dallas, the arts district and the northern neighborhood, which separates the spatial connection between the densely populated northern community, the downtown and northern residential areas of Dallas. The construction of the Clyde Warren Park solved this problem and restored the connection in this area (Figure 3).

Animal corridor refers to the roadway designed to protect animal migration. The animal corridor may be part of the zoo, or it may be a migration corridor designed to restore the natural state of being separated by artificial facilities. Houston's Memorial Park is an excellent example of this kind of infrastructural urbansim. It used to be a training ground for soldiers of World War I. After the war, it was built to commemorate the soldiers who died in war.However, due to the long-term separation of the roads and leisure activities in the nature reserve, the park's ecosystem and space quality are deteriorating. To improve this situation, Nelson Byrd Woltz Landscape Architects re-planned the park and one of the key points in the new plan was to plan a number of animal corridors that reconnected the parks that were segmented by the road (Figure 4).

Greenbelt refers to a strip-shaped or linear green open space. The green belt not only serves as a way to cope with the in fi nite spread of the city, but also provides residents with an ecological circle of activities, and maintaining the sustainable development of the city and the countryside. The green belt of this paper corresponds to the forest belt, protective green space and street tree. The green belt can be composed of these elements, but a single element does not necessarily form a green belt. Compared with Howard's green belt concept, the green belt corresponding to the infrastructure is more concerned about its connectivity and connection of the existing linear environment infrastructure segments.It also concerns about connecting the green space to build the urban green space system and enhance the community along the line. Ecology is the focus of urbanization of environment infrastructure. Bayou Greenways Master Plan is a good example of this kind of infrastructural urbanism. It allows the connection between Houston city garden and provides a significant amount of leisure space for the city,integrating existing public resources and providing valuable ecological public space for residents of the surrounding communities.

Garbage disposal facilities are places where facilities such as industrial, domestic production, medical care and the like are collected and disposed of. Beijing Garden Expo Park (Figure 6) was transformed from the famous Beijing construction waste dump,which was originally called “Yongding River Dasha Pit”. The park has improved the ecological environment and it is turned from a garbage dump that was originally unattended into a city green lung.

The green area refers to the green space in the city that is suitable for residents to enjoy leisure and recreation. As one of the founders of landscape design,Olmsted's representative work, the Emerald Necklace formed the effect of having a city in the park and a garden in the city (Figure 7). This green area made Boston a garden city. It consists of 9 urban parks with different themes, which use the ups and downs of the terrain to form an open urban green space with a rich and adaptable level to form a rich urban activity.

The urbanization process of environment infrastructure is the ecological process of the city, which requires us to fundamentally change the past understanding of environment infrastructure.