[中文]道路网
在北京1949年之后的道路发展中,东西向和南北向大道的开通成为最紧迫的工程。这对于工业、高等教育、研发、管理和居住新郊区的开发十分重要。因此,城市内部和郊区的道路里程从1949年的164公里增长了20倍,达到1991年的3276公里。机动车数量更是激增,从1950年的2328辆上涨到1991年的352.3千万辆。(北京统计年鉴,不同时期)。道路里程增加量和汽车数量增加量的比值为1:8,道路里程增加量和公共交通增加量的比值为1:6。这些也是大部分第三世界城市的共同特征(表2)。然而,北京在道路建设上的投资较少。北京在城市交通上的资本投入(约占道路建设和改善支出的35%)多年以来在城市基础设施总投入中都不到1%。多数投资发生在1949年之后的三年内和1978年改革开放政策实施之后。Quan(1988)指出,1978年至1988年间,城市投入了总计43亿元人民币进行交通建设,是之前年份年均值的6倍。这十年中,新增了634万平方米城市道路,占1978年总量的38.7%。
改善城市道路网的主要成就有:
(1)五条东西向道路和一条南北向干道的开通和/或拓宽;
(2)在新开发的居住区内建设10条6-10公里的大道,包括六条南北向和三条东西向的区级道路;
(3)在郊区,建设了13条主要放射道路,将那里的新开发区和老城区联系起来;
(4)建设了一些环路以减少老城区的交通(图1)。其中有19公里长的市中心主干道内环路;紧贴老城区原有城墙的23.7公里长的二环路(1993年建成);于1981年建成,主要连接各郊区的48公里长的三环路;第四条是65公里长的四环路,目前部分完工,主要为城市内部和城市间的货运交通服务。在二环路和三环路上,截至1989年,在交通繁忙的交叉口共建成了40座立交(图1)。这个环状放射道路系统基本沿袭了前苏联的交通规划模式。
这样,1949年后的道路建设将城市道路网的旧的格网形式,转变为环状道路和放射状道路混合的形式。三环路标志着旧的格网形式和郊区的城市外围放射状道路占据主导的分界。
道路网的另一个重要特征是自行车循环系统的形成,它体现了城市政府在城市交通战略中整合非机动交通方式的意图。从1949年到1965年,大部分新建的主干道包含14-21米宽、机非混行的单幅路车道。随着城市自行车使用的增加,1965年建设了第一条三幅路主干道,将这两种不同的交通方式分隔开来。它包含两条各14米宽的机动车道,和两条各4米宽的自行车、手推车车道。在二者之间是2.5-5.5米宽的绿化隔离带。到1983年底,建成了100公里的三幅路主干道,而到1991年增加到242公里(其中173公里在市内和郊区地区)。在将非机动交通方式整合到道路建设工程中的方面,中国在第三世界阵营中仍然颇具特色。
城市交通条件的恶化归咎于由经济和人口的增长带来的机动车拥有量和交通需求的增加,但道路网的空间增长不平衡也是原因之一。北京市城建局的一份报告表明,在规划区(城市中心650平方公里的地区)内有2000公里的道路(占总数的77.3%),但它们的空间分布却非常不均衡。在二环路以内有747公里(36.1%),二环路和三环路之间有426公里(20.6%),而在三环路和城市规划区边界之间有896公里(43.3%)。
在市中心地区(以二环路为界的62平方公里的老城区),主干路密度(7米以上宽度的道路)在所有城市分区中最高,可是道路质量较差。但是主干路只占中心区道路的9%,而且贯通的道路较少。然而老城区承载了28.7%的城市交通量,而且是城市中53%的通勤的起点。它的道路网已经达到容量的90%,但交通量还在以每年4.6%的速度增长,超过3%的城市平均值(Quan,1990)。1986年和1987年的交通调查表明在老城区内,机动车在主干路上的车速在仅仅一年内下降了40%,降至平均20公里/小时,而在23条主干路上只有10公里/小时。由于保护故宫和三海的需要,以及重新安置受道路拓宽方案影响的高密度居住区的高昂成本和诸多问题,导致了贯通性主干路的缺乏,制约了老北京城城市交通的改善。
由于内环路仍未建成且由于高成本和拆除已有建筑的高难度而道路标准较低,大部分区内交通不得不利用二环路完成。交通调查显示,93%的城市机动车流都是东西向,25%的内城交通流穿过内城。这种交通流模式和老北京城传统道路模式有冲突。为改善这种状况,更高标准的二环路和完工的四环路是必要的。放射状道路的标准也较低。它们多数仅有两条机动车道,而三环路内的许多部分还有很多未完工。
在城市规划区内的2000公里道路中,只有824公里宽度超过7米,能被机动车使用,包括100公里的4车道、横断面宽超过21米的高标准道路,以及235公里的12-21米宽、可机非分行的道路。60%的道路网宽度在7米一下,不能被机动车使用。只有497公里可能可以被救护车、消防车、垃圾车使用。其余的784公里只能通行自行车和行人(城建局,1987)。[/中文]
[外文]The road network
In Beijing’s post-1949 road development, the opening of the east-west and north-south arteries became the most urgent work. This was vital for the development of new suburbs for industries, high level education, R&D and administration, as well as for residential use. As a result, the road mileage within the city and suburban districts increased 20-fold from 164 km in 1949 to 3276 km in 1991. The motorized vehicle numbers increased more more rapidly from 2328 in 1950 to 384 451 in 1990, as did total urban public transport users which increased from 29 million persons in 1949 to 3523 million in 1991. (Beijing Statistical Yearbook, various dates). The ratio of road mileage to car population increase is 1:8, and road mileage to public transport volume 1: 6. These too are common features of most Third World cities (Table 2). Beijing has, however, invested less in road construction. Bejing’s capital investment in urban transport (about 35% of which is spent on road construction and improvement) has been for many years less than 1% of the city’s total infrastructural investment. Most investment was in the first three years after 1949 and in the years since the Open and Reform policy was adopted in 1978. Quan (1988a) showed that in 1978-1988, the city invested a total of Y4.3 billion in transport construction, six times the annual average of the years before. In these 10 years, 6.23 million sq. m of urban roads had been added, or 38.7% of the total at 1978.
The major achievements in improving the urban road network are:
(1) opening up and/or widening of five east-west roads and one north-south trunk road;
(2) construction of ten arteries of 6-10 km in newly developed residential areas, including six north- south and three east-west district roads;
(3) in the suburbs, 13 main radiating roads have been built to link new developments there with the Old City;
(4) a number of ring roads have been constructed to reduce traffic in the Old City (Figure I). They are the Inner Ring Road, the main artery of the central area, which is 19 km long; the Second Ring Road of 23.7 km, on the former wall of the Old City (completed in 1993); the Third Ring Road of 48 km, completed in 1981 which serves mainly as the link between the suburban districts; and fourthly, the Fourth Ring Road of 65 km, partly completed at present. The Fourth Ring Road is to serve mainly intra-urban and inter-urban freight transport. Over the Second and Third Ring Roads, by 1989, 40 flyovers had been completed at busy road junctions (Figure 1). This system of ring and radial roads is basically copied from the Soviet model of transport planning.
Thus, post-1949 road building has altered the old grid pattern of the city’s road network, to a mixture of ring roads and radial roads. The Third Ring Road marks the divide between the Old City’s grid pattern and the predominance of radial roads in the outer urban areas in the suburbs.
Another important feature of the road network is the emergence of a circulatory system for bicycles, reflecting the city government’s increased attempts to integrate non-motorized modes in its urban transport strategy. From 1949 to 1965, most new main roads contained 14-21 m wide lanes for cars, in single carriageways without separation for motorized and non-motorized traffic. With growing use of bicycles in the city, the first three-carriageway main road was constructed in 1965 which provides separations for the two different modes. It contains two motorized vehicular lanes of 14 m each, and two bicycle and cart lanes of 4 m each. In between them are green reservations 2.5-5.5 m wide. By the end of 1983, there were 100 km three-carriageway main roads which were increased to 242 km (173 km within the city and suburban districts) in 1991. China is still unique within the Third World in integrating non-motorized modes into its road construction programmes.
Urban transport conditions have deteriorated due to rapid growth of motor car ownership and transport demand arising from economic and population growth, yet the imbalance in spatial growth of the network is partly responsible. A report of the Civil Engineering Bureau of the municipality revealed that there were 2000 km of roads (77.3% of total) within the planned urban areas (an area of 650 sq. km at the centre of the municipality), but their spatial distribution is however highly uneven. Within Second Ring Road were 747 km (36.1%) between the Second and Third Ring Road, 426 km (20.6%) and between the boundary of the planned urban areas and Third Ring Road were 896 km (43.3%).
Within the central area (the Old City of 62 sq. km marked by the Second Ring Road), main road density (roads of 7 m width and above) is the highest of all the urban zones, yet the quality of its roads are low. Main roads, however, only accounted for 9% of central area roads and it has few through-roads. The Old City, nevertheless, accommodated 28.7% of the urban traffic and was the origin of 53% of the commuting trips of the city. Its road network had already reached a capacity of 90% and yet its traffic volume was still growing at a rate of 4.6% per year, exceeding the city average of 3% (Quan, 1990a). Traffic surveys in 1986 and 1987 show that within the Old City, the speed of motorized vehicles on main roads dropped 40% in one year alone, to an average of 20 km/hour, while on 23 main roads it was only 10 km/hour. Inadequacy of main through-roads, arising both from the need to preserve the Forbidden City and San Hai, as well as high costs and problems of resettlement of the densely populated areas affected by road widening schemes, have constrained urban transport improvement in old Beijing.
As the Inner Ring road is still incomplete and of low standard due to the high costs and difficulty of demolition of existing housing, most inter-district traffic has to use the Second Ring Road. Traffic surveys indicated that 93% of the vehicle flow of the city is in an east- west direction and 25% of the inter-city flow passes through the inner city. This pattern of traffic flow is at conflict with the traditional street pattern of the Old City. A higher standard Second Ring Road and a completed Fourth Ring Road are certainly necessary in order to improve the situation. The standards of the radiating roads are also low. They mostly contain only two lanes for motorized vehicles, and sections on the inside of the Third Ring Road are still largely uncompleted.
Of the 2000 km of roads within the planned urban areas, only 824 km are of a width of over 7 m and could be used by motorized vehicles, including 100 km of high standard roads with four lanes and a total surfaced width of over 21 m and 235 km of 12-21 m width roads, which allow for some separation of motorized and non-motorized traffic. 60% of the road network are, therefore, below 7 m in width and cannot normally be used for motorized traffic. Only about 497 km may be used by ambulances, fire-engines and refuse collecting vehicles in emergencies. The remaining 748 km are only used for bicycle and pedestrian traffic (Civil Engineering Bureau, 1987).[/外文]
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