Development of district-wise crash prediction model in Bangladesh

Figures & data

Figure 1. Crash frequency by severity in all 64 districts in Bangladesh (Aggregated data from 2009 to 2013)

Figure 2. Road network in Bangladesh (Source: HDM circle, roads and highways department of Bangladesh)

Table 1. Description of road infrastructure, socio-economic, demographic and weather data

Road Infrastructures	Description
Box Culvert	The total number is 9442. This structure usually has 1 to 2 boxes/spans. Span length varies from 3 to 5 m, the abutment, pier wall, and wing wall are made of RCC, wearing surface is bituminous and railing type is RCC made.
Slab Culvert	The total number is 3991. The structure usually has 1 to 2 boxes/spans, span length varies from 1.5 to 7 m, the abutment, pier wall, and wing wall are made of either RCC or masonry, wearing surface is bituminous and railing type is RCC made.
RCC Girder Bridge	The total number is 2387. The structure usually has 1 to 4 boxes/spans, span length is 12 to 17 m on average, the abutment, pier wall, and wing wall are made of RCC, wearing surface is made of bitumen or concrete, railing type is RCC made.
PC Girder Bridge	The total number is 405. The structure usually has 5 to 6 spans on average, span length is around 15 m in average, the abutment, pier wall, and wing wall are made of RCC, wearing surface is made of bitumen or concrete, railing type is RCC made.
RCC Bridge	The total number is 244. The structure usually has 5 to 7 spans in average, span length is around 20 m in average, often beams are present with 2 to 4 in number, the abutment, pier wall, and wing wall are made of RCC and very few are of masonry, wearing surface is made of bitumen or concrete, railing type is RCC made.
Arch Masonry	The total number is 318. The structure usually has 1 to 4 spans on average, span length is 2–6 m in average, the abutment, pier wall, and wing wall are made of masonry, wearing surface is made of bitumen, most of the railing types are masonry, often RCC made railings are found.
Truss with Steel Deck	The total number is 204. The structure usually has 2 to 10 spans in average, span length ranges from 20 m to 140 m, the number of beams is usually 2 to 8, the abutment, pier wall, and wing wall are made of RCC, wearing surface is made of bitumen or concrete, railing type is steel made.
Truss with RCC Slab	The total number is 30. The structure usually has 1 to 5 spans, span length ranges from 10 m to 80 m, the abutment, 3 to 6 beams are present, pier wall and wing wall are made of RCC, wearing surface is made of bitumen or concrete, railing type is RCC and steel made.
Truss with Timber Deck	The total number is 6. The structure usually has 1 to 13 spans, span length ranges from 5 to 50 m, the abutment, pier wall, and wing wall are made of RCC and masonry, wearing surface is made of bitumen or concrete, railing type is usually steel made.
Baily with Steel Deck	The total number is 973. The structure usually has 1 to 6 spans, span length is around 30 m on average, the abutment, pier wall, and wing wall are made of RCC and very few are of masonry, wearing surface is made of bitumen, railing type is RCC and steel made.
Baily with Timber Deck	The total number is 23. The structure usually has 1 to 4spans, span length ranges from 4 to 40 m, the abutment, pier wall, and wing wall are made of RCC, wearing surface is made of bitumen, railing type is steel made.
Steel Beam and RCC Slab	The total number is 230. The structure usually has 1 to 5 spans, span length is around 15 m in average, the abutment, pier wall, and wing wall are made of masonry and RCC, wearing surface is made of bitumen, railing type is RCC/steel made.
Pre-stressed Concrete	The total number is 5. The structure usually has 5 to 24 spans on average, span length ranges from 30 to 90 m, the abutment, pier wall, and wing wall are made of RCC, wearing surface is made of concrete, railing type is RCC post and rail.
Road Networks	Description
National Highways (NH)	Connecting national capital with divisional headquarters (HQ’s), seaports and land ports. It has usually a high percentage of vehicle-kilometers (59%)
Regional Highways (RH)	Connecting district headquarters with land or river ports that are not connected with National highways. District HQ’s are also connected by RH. It has usually a moderate percentage of vehicle-kilometers (23.3%)
Zilla Roads (ZR)	Connecting district to Upazila, Upazila to Upazila, Upazila to NH/RH with a short distance route. It has usually a low percentage of vehicle-kilometers (17.7%)
Upazilla Roads	Connecting Upazilla HQ’s to growth center or growth center to center, connecting center to ZR/RH.
Union Roads	Connecting Union HQ’s to Upazilla HQ’s, to local markets or growth center to each other.
Village Roads (VR)	Connecting villages with union HQ’s, local markets, farms and roads within villages.
Roads not surveyed	Roads that are not surveyed mean that AADT, pavement types, road lengths, etc. are not surveyed yet or these roads are under construction.
Road Pavement Types	Description
Flexible Pavement	Composed of series of granular layers (bituminous or non-bituminous) with thin layers of wearing surface. The number of layers depends on traffic flow.
Rigid Pavement	Implies Portland cement concrete slab acts as a wearing surface of the road.
Brick Pavement	Made of brick with a leveled sub-grade.
Earthen Pavement	Made of soil with a specific range of plasticity index.
Others	Description
Structure span length	Length of structural spans in Union, Upazilla and Village roads
No. of Structure span	Number of structural spans in Union, Upazilla and Village roads
No. of existing gap	Number of existing gap between road structures in Union, Upazilla and Village roads
Length of existing gap	Length of existing gap among road structures in Union, Upazilla and Village roads
Socio-economic Data	Description
General Household	District wise households having usual dwelling places
Institutional Household	District wise hospitals, clinics, jails, orphanages, hostels/halls of educational institutions.
Other Household	Households other than general and institutional household, e.g., messes, shops, offices
Weather	Description
Rainfall	Rainfall data for each of 64 districts of Bangladesh (2009–2013). Unit: mm
Visibility	Data of visibility for each of the 64 districts were extracted (2009–2013), Unit: km
Minimum Temperature	Minimum temperature data for each of the 64 districts (2009–2013) Unit: °C

Table 2. Descriptive statistics of four types of crash, road infrastructures, socio-economic and demographic conditions, and weather conditions of all districts in Bangladesh

Variable Name		Mean	Std. Dev
Dependent variable (5-year aggregated number of crash, 2009–2013)
Fatal crash		102.70	62.49
Grievous crash		17.89	11.00
Minor crash		3.75	3.69
Property damage only (PDO) crash		1.92	2.48
Independent variables
Road infrastructures in National, Regional and Zilla highways (lengths aggregated for 64 districts)
National Highway (km)
Box- Culvert		225.69	255.53
RCC Bridge		24.59	78.25
Steel Beam &RCC Slab		55.03	132.03
PC Girder		546.78	1001.84
Slab Culvert		15.80	28.19
Regional Highway (km)
Arch Masonry		6.78	18.87
RCC Bridge		22.45	45.23
Steel Beam &RCC Slab		18.48	75.48
Baily with Steel Deck		149.45	270.12
Zilla Highway (km)
Arch Masonry		5.86	10.77
Pre-stressed Concrete		4.91	38.94
PC Girder		368.16	598.53
Truss with RCC Slab		22.76	107.74
Steel Beam & RCC Slab		49.34	118.81
Baily with Timber Deck		10.75	36.24
RCC Girder Bridge		908.43	638.26
Baily with Steel Deck		558.37	783.18
Truss with Steel Deck		313.55	359.53
Length of different road networks (km)
National Highway		55.92	50.62
Regional Highway		66.81	51.67
Zilla Road		209.73	104.10
Length not surveyed		22.71	31.09
Pavement types in Union, Upazilla and Zilla roads (km)
Union Road
Flexible pavement		300.02	170.83
Rigid pavement		12.11	31.80
Brick pavement		49.78	68.41
Earthen road		320.81	247.04
Paved road		282.91	117.41
No. of Structure span		965.69	594.15
No. of existing gap		99.34	133.91
Upazilla Road
No. of Structure span		965.69	594.15
Brick pavement (km)		22.67	27.12
No. of existing gap		55.92	85.69
Village Road
Flexible Pavement		360.62	247.19
No. of Existing gap		986.07	881.62
No. of Structure span		2079.92	1566.32
Length of span (km)		9610.07	5441.92
Socio-economic and Demographic Characteristics
General Household		486989.71	364924.43
Other Household		4335.56	17439.57
Institutional Household		411.69	765.04
Sex ratio (M/F)		112.84	111.12
Weather conditions
Rainfall (mm)
2009		2016.33	585.38
2011		2161.18	575.82
2013		2057.17	691.10
Visibility/Fog
2009		75	45.73
Average minimum temperature (°C)
2009		21.63	1.31
2010		21.90	1.37
2011		21.17	1.23
2012		21.39	1.34
2013		21.11	1.25

Table 3. Parameter estimates of all 4 crashes

Variables			Estimated coefficient (β) and p-values of crash severity models
			Fatal	Grievous	Minor	Property Damage
Road Infrastructure National Road (km)
Box- Culvert			0.00041 (<0.0001)	0.00095 (<0.0001)
RCC Bridge			0.00212 (<0.0001)	0.00070 (0.053)	0.0038 (<0.0001)	0.0042 (0.017)
Steel Beam &RCC Slab			−0.00041 (0.015)
PC Girder				−0.000081 (0.056)
Slab Culvert						0.0093 (0.023)
Regional Highway (km)
Arch Masonry			−0.00535 (<0.0001)
RCC Bridge			−0.00126 (0.018)	0.00023 (0.009)		−0.1016 (0.002)
Steel Beam & RCC Slab				−0.00072 (0.090)		0.00176 (0.029)
Baily with Steel Deck				0.00078 (<0.0001)	−0.0015 (0.002)	−0.0152 (0.003)
Zilla Road (km)
Arch Masonry				0.0102 (0.003)		0.0288 (0.031)
Pre-stressed Concrete			−0.00282 (<0.0001)
PC Girder			0.00025 (<0.0001)		0.00043 (0.016)	0.00067 (<0.0001)
Truss with RCC Slab			−0.00078 (0.001)		−0.00399 (0.044)
Steel Beam & RCC Slab				−0.00073 (0.077)
Baily with Timber Deck						−0.01523 (0.003)
RCC Girder Bridge				0.00018 (0.003)	−0.00057 (0.015)
Baily with Steel Deck				−0.00072 (0.003)
Truss with Steel Deck					0.00059 (<0.0001)
Highway Length (km)
National Highway			0.0057 (<0.0001)		0.0135 (<0.0001)
Regional Road						0.00407 (0.10)
Zilla Road			−0.00108 (<0.0001)
Length not Surveyed				0.0053 (0.001)
Union road (km)
Rigid pavement		0.0078 (<0.0001)			0.014 (<0.0001)
Brick pavement				−0.0034 (<0.0001)
Earthen road						−0.00086 (0.097)
Number of span		0.00037 (<0.0001)
Existing gap number		−0.00227 (<0.0001)
Upazilla Road
Brick pavement (km)				0.0044 (0.005)
Village road
Number of Existing gap		0.00033 (<0.0001)
Length of span (km)				0.000033 (<0.0001)
Flexible Pavement						0.00090 (0.052)
Socio-economic and Demographic Characteristics
Institutional Household	0.000042 (0.039)
Other Household				−0.000011 (0.001)
Weather Rainfall (mm)
Year 2009	−0.00032 (<0.0001)
Year 2011					−0.00090 (<0.0001)
Year 2013					0.00051 (0.015)	−0.000387 (0.034)
Visibility (km)
Visibility 2009	−0.00273 (<0.0001)
Average minimum temperature (°C)
Year 2009				−1.0258 (<0.0001)
Year 2012				1.0942 (<0.0001)
Year 2013						0.2822 (0.001)
Number of observation	64			64	64	64
LR χ2	1447.67			242.85	125.75	90.77
Pseudo R2	0.78			0.36	0.46	0.33
Log likelihood	−199.74			−214.08	−73.16	−93.86

(NB: The values in the parentheses are p-values with 90% CI)